2023

Jump to: 2022, 2021, 2020, 2019, 2018, 2017

15 pages, 5666 KiB

Open AccessArticle

Use of a Photocleavable Initiator to Characterize Polymer Chains Grafted onto a Metal Plate with the Grafting-from Method

by Flavien Mouillard, Tom Ferté, Emilie Voirin, Stéphane Méry, Patrick Masson and Adele Carradò

Polymers 2023, 15(5), 1265; https://doi.org/10.3390/polym15051265 - 02 Mar 2023

Viewed by 1588

Abstract

The thorough characterization of polymer chains grafted through a “grafting-from” process onto substrates based on the determination of number (Mn) and weight (Mw) average molar masses, as well as dispersity (Ɖ), is quite challenging. It requires the cleavage of grafted chains selectively at [...] Read more.

The thorough characterization of polymer chains grafted through a “grafting-from” process onto substrates based on the determination of number (Mn) and weight (Mw) average molar masses, as well as dispersity (Ɖ), is quite challenging. It requires the cleavage of grafted chains selectively at the polymer–substrate bond without polymer degradation to allow their analysis in solution with steric exclusion chromatography, in particular. The study herein describes a technique for the selective cleavage of PMMA grafted onto titanium substrate (Ti-PMMA) using an anchoring molecule that combines an atom transfer radical polymerization (ATRP) initiator and a UV-cleavable moiety. This technique allows the demonstration of the efficiency of the ATRP of PMMA on titanium substrates and verification that the chains were grown homogeneously. Full article

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14 pages, 4580 KiB

Open AccessArticle

Dynamic Wetting Properties of Silica-Poly (Acrylic Acid) Superhydrophilic Coatings

by Sevil Turkoglu, Jinde Zhang, Hanna Dodiuk, Samuel Kenig, Jo Ann Ratto and Joey Mead

Polymers 2023, 15(5), 1242; https://doi.org/10.3390/polym15051242 - 28 Feb 2023

Cited by 5 | Viewed by 1876

Abstract

Superhydrophilic coatings based on a hydrophilic silica nanoparticle suspension and Poly (acrylic acid) (PAA) were prepared by dip coating. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to examine the morphology of the coating. The effect of surface morphology on [...] Read more.

Superhydrophilic coatings based on a hydrophilic silica nanoparticle suspension and Poly (acrylic acid) (PAA) were prepared by dip coating. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to examine the morphology of the coating. The effect of surface morphology on the dynamic wetting behavior of the superhydrophilic coatings was studied by changing the silica suspension concentration from 0.5% wt. to 3.2% wt. while keeping the silica concentration in the dry coating constant. The droplet base diameter and dynamic contact angle with respect to time were measured using a high-speed camera. A power law was found to describe the relationship between the droplet diameter and time. A significantly low experimental power law index was obtained for all the coatings. Both roughness and volume loss during spreading were suggested to be responsible for the low index values. The water adsorption of the coatings was found to be the reason for the volume loss during spreading. The coatings exhibited good adherence to the substrates and retention of hydrophilic properties under mild abrasion. Full article

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2022

Jump to: 2023, 2021, 2020, 2019, 2018, 2017

16 pages, 4271 KiB

Open AccessArticle

Polyethylene Glycol-b-poly(trialkylsilyl methacrylate-co-methyl methacrylate) Hydrolyzable Block Copolymers for Eco-Friendly Self-Polishing Marine Coatings

by Elisa Guazzelli, Matteo Oliva, Carlo Pretti, Gianfranca Monni, Armand Fahs, Christine Bressy and Elisa Martinelli

Polymers 2022, 14(21), 4589; https://doi.org/10.3390/polym14214589 - 28 Oct 2022

Cited by 3 | Viewed by 1813

Abstract

Hydrolyzable block copolymers consisting of a polyethylene glycol (PEG) first block and a random poly(trialkylsilyl methacrylate (TRSiMA, R = butyl, isopropyl)-co-methyl methacrylate (MMA)) second block were synthesized by RAFT polymerization. Two PEGs with different molar masses (M_n = 750 [...] Read more.

Hydrolyzable block copolymers consisting of a polyethylene glycol (PEG) first block and a random poly(trialkylsilyl methacrylate (TRSiMA, R = butyl, isopropyl)-co-methyl methacrylate (MMA)) second block were synthesized by RAFT polymerization. Two PEGs with different molar masses (M_n = 750 g/mol (PEG1) and 2200 g/mol (PEG2)) were used as macro-chain transfer agents and the polymerization conditions were set in order to obtain copolymers with a comparable mole content of trialkylsilyl methacrylate (~30 mole%) and two different PEG mole percentages of 10 and 30 mole%. The hydrolysis rates of PEG-b-(TRSiMA-co-MMA) in a THF/basic (pH = 10) water solution were shown to drastically depend on the nature of the trialkylsilyl groups and the mole content of the PEG block. Films of selected copolymers were also found to undergo hydrolysis in artificial seawater (ASW), with tunable erosion kinetics that were modulated by varying the copolymer design. Measurements of the advancing and receding contact angles of water as a function of the immersion time in the ASW confirmed the ability of the copolymer film surfaces to respond to the water environment as a result of two different mechanisms: (i) the hydrolysis of the silylester groups that prevailed in TBSiMA-based copolymers; and (ii) a major surface exposure of hydrophilic PEG chains that was predominant for TPSiMA-based copolymers. AFM analysis revealed that the surface nano-roughness increased upon immersion in ASW. The erosion of copolymer film surfaces resulted in a self-polishing, antifouling behavior against the diatom Navicula salinicola. The amount of settled diatoms depended on the hydrolysis rate of the copolymers. Full article

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15 pages, 3354 KiB

Open AccessArticle

Optimizing the Composition of Silicone Enamel to Ensure Maximum Aggregative Stability of Its Suspensions Using Surfactant Obtained from Oil Refining Waste

by Vitaliy Tyukanko, Alexandr Demyanenko, Antonina Dyuryagina, Kirill Ostrovnoy and Gulsim Aubakirova

Polymers 2022, 14(18), 3819; https://doi.org/10.3390/polym14183819 - 13 Sep 2022

Cited by 6 | Viewed by 1227

Abstract

The aim of this study was to optimize the composition of enamel consisting of aluminum pigment and polyphenylsiloxane polymer, in order to achieve the maximum aggregative stability of suspensions. Sedimentation rate (SR) was used as a criterion for assessing the aggregative stability of [...] Read more.

The aim of this study was to optimize the composition of enamel consisting of aluminum pigment and polyphenylsiloxane polymer, in order to achieve the maximum aggregative stability of suspensions. Sedimentation rate (SR) was used as a criterion for assessing the aggregative stability of the suspensions. An original product, AS-1, and industrial additives PEPA and Telaz, were tested as surfactants. AS-1 was obtained from oil refining waste at M. Kozybayev North Kazakhstan University. All the studied surfactants improved the stability of the suspensions. The AS-1 additive significantly improved the stability of the suspensions, but exhibited a lower stabilizing ability by 10–20% than PEPA. The maximum overall stability of the suspensions was recorded at a PEPA level of 0.25–0.375 g/dm³ in the enamel. The Taguchi method was used to optimize the composition of the enamel, using AS-1 as the surfactant. It is recommended to use AS-1 in silicone enamels. Optimum compositions can reduce the petrol absorption of coatings by 1.5 times, their roughness by 2.5 times and increase their gloss. Full article

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14 pages, 41140 KiB

Open AccessArticle

Effect of Water-Resistant Properties of Kraft Paper (KP) Using Sulfur Hexafluoride (SF₆) Plasma Coating

by Pornchai Rachtanapun, Dheerawan Boonyawan, Rafael A. Auras and Gopinath Kasi

Polymers 2022, 14(18), 3796; https://doi.org/10.3390/polym14183796 - 10 Sep 2022

Cited by 3 | Viewed by 1699

Abstract

Sulfur hexafluoride (SF₆) plasma at different pressures, powers, and times was used to treat Kraft paper (KP) to enhance its water resistance. The KP was treated with SF₆ plasma from 20–300 mTorr of pressure at powers from 25–75 Watts and [...] Read more.

Sulfur hexafluoride (SF₆) plasma at different pressures, powers, and times was used to treat Kraft paper (KP) to enhance its water resistance. The KP was treated with SF₆ plasma from 20–300 mTorr of pressure at powers from 25–75 Watts and treatment times from 1–30 min at 13.56 MHz. The prepared papers were characterized by contact angle measurement and water absorption. The selected optimum condition for the plasma-treated KP was 200 mTorr at 50 Watts for 5 min. Advancement with the change in treatment times (3, 5, and 7 min) on the physical and mechanical properties, water resistance, and morphology of KP with SF₆ plasma at 200 mTorr and 50 Watts was evaluated. The changes in the chemical compositions of the plasma-treated papers were analyzed with an XPS analysis. The treatment times of 0, 3, 5, and 7 min revealed fluorine/carbon (F/C) atomic concentration percentages at 0.00/72.70, 40.48/40.97, 40.18/37.95, and 45.72/39.48, respectively. The XPS spectra showed three newly raised peaks at 289.7~289.8, 291.5~291.7, and 293.4~293.6 eV in the 3, 5, and 7 min plasma-treated KPs belonging to the CF, CF₂, and CF₃ moieties. The 5 min plasma-treated paper promoted a better interaction between the SF₆ plasma and the paper yielded by the F atoms. As the treatment time for the treated KPs increased, the contact angle, water absorption time, and Cobb test values increased. However, the thickness and tensile strength did not show remarkable changes. The SEM images revealed that, as the treatment time increased, the surface roughness of the plasma-treated KPs also increased, leading to improved water resistance properties. Overall, the SF₆ plasma treatment modified the surface at the nano-layer range, creating super-hydrophobicity surfaces. Full article

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12 pages, 2713 KiB

Open AccessArticle

Synergistic Effect between Piperazine Pyrophosphate and Melamine Polyphosphate in Flame Retardant Coatings for Structural Steel

by Lianliang Li, Yating Huang, Wei Tang, Yi Zhang and Lijun Qian

Polymers 2022, 14(18), 3722; https://doi.org/10.3390/polym14183722 - 06 Sep 2022

Cited by 7 | Viewed by 2189

Abstract

Piperazine pyrophosphate (PAPP) combined with melamine polyphosphate (MPP) was adopted to prepare a waterborne fire retardant intumescent coating (IC) for structural steel. Silicone acrylic emulsion was used as binder. In the 2-h torch test, PAPP/MPP-IC coating presented excellent fire resistance performance. The equilibrium [...] Read more.

Piperazine pyrophosphate (PAPP) combined with melamine polyphosphate (MPP) was adopted to prepare a waterborne fire retardant intumescent coating (IC) for structural steel. Silicone acrylic emulsion was used as binder. In the 2-h torch test, PAPP/MPP-IC coating presented excellent fire resistance performance. The equilibrium temperature at the backside of the steel board decreased to 170 °C with protection of MPP/PAPP-IC, compared with 326 °C of APP/PER/MEL-IC. After 72-h water immersion, MPP/PAPP-IC could still provide sufficient thermal isolation, but APP/PER/MEL-IC failed the test. The water absorption of the MPP/PAPP coating was also reduced. The thermogravimetric analysis measured that the PAPP/MPP-IC had unique initial decomposition temperature of 296 °C and higher residue of 33.8 wt%, which demonstrated better thermal stability and fire retardancy in condensed phase. In addition, Scanning Electron Microscope (SEM) images illustrated that the structure of the carbon layer formed by MPP/PAPP-IC was dense, complete and consistent, indicating the improvement of mechanical strength and thermal isolation of the char. The synergistic effect between piperazine and phosphoric acid groups in MPP/PAPP contributed to the superior flame retardancy. Consequently, MPP/PAPP-IC was much more efficient than the traditional APP/PER/MEL-IC. This work provides a novel way for designing flame retardant coatings for structural steel with excellent comprehensive performance. Full article

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22 pages, 5276 KiB

Open AccessArticle

Effect of Transparent, Purple, and Yellow Shellac Microcapsules on Properties of the Coating on Paraberlinia bifoliolata Surface

by Yan Han, Xiaoxing Yan and Yu Tao

Polymers 2022, 14(16), 3304; https://doi.org/10.3390/polym14163304 - 13 Aug 2022

Cited by 9 | Viewed by 1237

Abstract

In order to explore the applicability of the waterborne coating with self-repairing microcapsules based on the surface of wood boards and specify the optimal range of microcapsule content in the coating, three different kinds of shellac microcapsules (transparent shellac, purple shellac, and yellow [...] Read more.

In order to explore the applicability of the waterborne coating with self-repairing microcapsules based on the surface of wood boards and specify the optimal range of microcapsule content in the coating, three different kinds of shellac microcapsules (transparent shellac, purple shellac, and yellow shellac) were embedded in a waterborne acrylic coating at 0, 1.5 wt.%, 3.0 wt.%, 4.5 wt.%, 6.0 wt.%, and 7.5 wt.%. The Beli wood (Paraberlinia bifoliolata) boards were then covered with self-repairing coatings to investigate the self-repairing coating’s physical and chemical properties, aging resistance, and scratch repair abilities. The findings demonstrated that the chromatic difference and gloss of surface coatings on Beli wood boards were significantly influenced by the content of microcapsules. The optical characteristics and cold liquid resistance performance of the coating on Beli wood were enhanced when the microcapsule content was 3.0 wt.%. Additionally, the mechanical qualities of the coating with 3.0 wt.% transparent shellac microcapsules on Beli wood surface were better, with an H hardness, grade 2 adhesion, and 8 kg·cm of impact strength. The studies on scratch repairing and aging resistance indicated that microcapsules helped to slow down the coating’s damage and retard aging. After a microcrack appeared, the waterborne coating with microcapsules on Beli wood’s surface had the capacity to repair itself. After aging, the coating with 3.0 wt.% transparent shellac microcapsule on Beli wood boards had a better performance on the comprehensive properties, with a 28.9% light loss rate and a 6 kg·cm impact resistance. It also had a 25.0% repairing rate in scratch width after being damaged for 5 d. This study advances the development of self-healing waterborne coatings on the wood board with shellac microcapsules by examining the effects of shellac in various colors and shellac microcapsule content in waterborne coatings. Full article

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33 pages, 2833 KiB

Open AccessReview

Flame Retardant Coatings: Additives, Binders, and Fillers

by Mohd Meer Saddiq Mohd Sabee, Zarina Itam, Salmia Beddu, Nazirul Mubin Zahari, Nur Liyana Mohd Kamal, Daud Mohamad, Norzeity Amalin Zulkepli, Mohamad Danial Shafiq and Zuratul Ain Abdul Hamid

Polymers 2022, 14(14), 2911; https://doi.org/10.3390/polym14142911 - 17 Jul 2022

Cited by 18 | Viewed by 9712

Abstract

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem [...] Read more.

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living. Full article

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20 pages, 5434 KiB

Open AccessReview

Free-Radical Photopolymerization for Curing Products for Refinish Coatings Market

by Aina Ribas-Massonis, Magalí Cicujano, Josep Duran, Emili Besalú and Albert Poater

Polymers 2022, 14(14), 2856; https://doi.org/10.3390/polym14142856 - 13 Jul 2022

Cited by 36 | Viewed by 4346

Abstract

Even though there are many photocurable compositions that are cured by cationic photopolymerization mechanisms, UV curing generally consists of the formation of cross-linking covalent bonds between a resin and monomers via a photoinitiated free radical polymerization reaction, obtaining a three-dimensional polymer network. One [...] Read more.

Even though there are many photocurable compositions that are cured by cationic photopolymerization mechanisms, UV curing generally consists of the formation of cross-linking covalent bonds between a resin and monomers via a photoinitiated free radical polymerization reaction, obtaining a three-dimensional polymer network. One of its many applications is in the refinish coatings market, where putties, primers and clear coats can be cured faster and more efficiently than with traditional curing. All these products contain the same essential components, which are resin, monomers and photoinitiators, the latter being the source of free radicals. They may also include additives used to achieve a certain consistency, but always taking into account the avoidance of damage to the UV curing—for example, by removing light from the innermost layers. Surface curing also has its challenges since it can be easily inhibited by oxygen, although this can be solved by adding scavengers such as amines or thiols, able to react with the otherwise inactive peroxy radicals and continue the propagation of the polymerization reaction. In this review article, we cover a broad analysis from the organic point of view to the industrial applications of this line of research, with a wide current and future range of uses. Full article

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28 pages, 5538 KiB

Open AccessReview

Electrochemical Characterization of Polymeric Coatings for Corrosion Protection: A Review of Advances and Perspectives

by Andressa Trentin, Amirhossein Pakseresht, Alicia Duran, Yolanda Castro and Dušan Galusek

Polymers 2022, 14(12), 2306; https://doi.org/10.3390/polym14122306 - 07 Jun 2022

Cited by 28 | Viewed by 5134

Abstract

The development of anti-corrosion polymeric coatings has grown exponentially in the fields of material science, chemistry, engineering, and nanotechnology during the last century and has prompted the evolution of efficient characterization techniques. Nowadays, polymeric coatings represent a well-established protection system that provides a [...] Read more.

The development of anti-corrosion polymeric coatings has grown exponentially in the fields of material science, chemistry, engineering, and nanotechnology during the last century and has prompted the evolution of efficient characterization techniques. Nowadays, polymeric coatings represent a well-established protection system that provides a barrier between a metallic substrate and the environment. However, the increase in complexity and functionality of these coatings requires high-precision techniques capable of predicting failures and providing smart protection. This review summarizes the state of the art for the main electrochemical techniques, emphasizing devices that track the anti-corrosion properties of polymeric coatings from the macroscale to the nanoscale. An overview of the advances in accelerated corrosion testing and the electrochemical characterization of coatings is explored, including insights into their advantages and limitations. In addition, the challenges and potential applications of the theoretical approaches are summarized based on current knowledge. Finally, this work provides the reader with the trends and challenges of designing future technologies and models capable of tracking corrosion and predicting failures. Full article

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15 pages, 2919 KiB

Open AccessArticle

Preparation of Tung Oil Microcapsule and Its Effect on Wood Surface Coating

by Wenwen Peng and Xiaoxing Yan

Polymers 2022, 14(8), 1536; https://doi.org/10.3390/polym14081536 - 11 Apr 2022

Cited by 13 | Viewed by 2140

Abstract

Through the optimized preparation of tung oil microcapsules, five kinds of microcapsules containing different core material content were obtained to explore the influence of microcapsules on water-based paint film and the self-healing ability of microcapsules. The results showed that the microcapsules had good [...] Read more.

Through the optimized preparation of tung oil microcapsules, five kinds of microcapsules containing different core material content were obtained to explore the influence of microcapsules on water-based paint film and the self-healing ability of microcapsules. The results showed that the microcapsules had good appearance, and the microcapsules were successfully prepared. The color difference in the paint film increased with the increase in microcapsule content, and the gloss decreased gradually. The mechanical test showed that adding microcapsules increased the toughness of the paint film to a certain extent, and the performance of the paint film was unchanged or better. The results showed that paint film with the core–wall ratio of 0.78:1 had the best performance and self-healing function when microcapsules were added. Full article

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19 pages, 5791 KiB

Open AccessArticle

Preparation of Thermochromic Microcapsules of Bisphenol A and Crystal Violet Lactone and Their Effect on Coating Properties

by Wenting Zhao and Xiaoxing Yan

Polymers 2022, 14(7), 1393; https://doi.org/10.3390/polym14071393 - 29 Mar 2022

Cited by 16 | Viewed by 2335

Abstract

Thermochromic microcapsules were prepared with a thermochromic compound as core material and urea formaldehyde as wall material. The molar ratio of urea and formaldehyde, the mass ratio of core material to wall material, the concentration of emulsifier, and rotating speed were selected to [...] Read more.

Thermochromic microcapsules were prepared with a thermochromic compound as core material and urea formaldehyde as wall material. The molar ratio of urea and formaldehyde, the mass ratio of core material to wall material, the concentration of emulsifier, and rotating speed were selected to make a four-level and three-factor L₉(3⁴) orthogonal test. It was found that the molar ratio of urea and formaldehyde had the greatest influence on the coating rate of microcapsules. The effects of molar ratio of urea and formaldehyde on the discoloration temperature and coating rate of microcapsules were studied. When the molar ratio of urea to formaldehyde was 1:1.6, the core material: wall material ratio was 4:7, the concentration of emulsifier was 5.0%, and the rotating speed was 1600 rpm, the performance of the microcapsules was the best. When the microcapsule content was 20.0%, the color difference of the paint film was the largest, the gloss and hardness of the paint film decreased with increasing microcapsule content, and the impact resistance of the paint film first increased and then decreased with increasing microcapsule content. The adhesion of the paint film remained unchanged, and was grade 1. When the microcapsule content was 20.0%, the performance of the paint film was at its best. This provides a basis for the application of thermochromic coatings. Full article

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20 pages, 3533 KiB

Open AccessArticle

Influence of HLB Value of Emulsifier on the Properties of Microcapsules and Self-Healing Properties of Waterborne Coatings

by Yu Tao and Xiaoxing Yan

Polymers 2022, 14(7), 1304; https://doi.org/10.3390/polym14071304 - 24 Mar 2022

Cited by 16 | Viewed by 2286

Abstract

In this paper, self-healing microcapsules were prepared by using melamine–formaldehyde (MF) resin as the wall material and shellac as the core material repairing agent. In order to explore the effect of the four factors (i.e., the HLB value of emulsifier, the type of [...] Read more.

In this paper, self-healing microcapsules were prepared by using melamine–formaldehyde (MF) resin as the wall material and shellac as the core material repairing agent. In order to explore the effect of the four factors (i.e., the HLB value of emulsifier, the type of solvent, the mass ratio of shellac to rosin, and the rate of rotating) on the comprehensive performance of microcapsules, and orthogonal experiments with four factors and three levels were carried out. The results showed that the hydrophilic lipophilic balance (HLB) value of the emulsifier was the most important influencing factor. In order to further explore the relationship between the HLB value of the emulsifier and the morphology of the microcapsules and the coating rate as well as to further optimize the performance of the microcapsules, taking the HLB value of the emulsifier as the single factor variable, single-factor tests were carried out. The results showed that when the HLB value was 12.56, the microcapsules of melamine–formaldehyde resin-coated shellac–rosin mixture had a uniform distribution and high coating rate. In order to explore the self-healing properties of waterborne coatings with microcapsules, the microcapsules prepared by single-factor experiments were mixed into the waterborne coatings at mass ratios of 0%, 3.0%, 6.0%, 9.0%, 12.0%, and 15.0%. It showed that the elongation at break of the waterborne coating with the addition of 3.0% microcapsule at mass fraction was improved, and it had a higher repair rate. This study provides a new research idea for the optimization and characterization of the self-healing properties of waterborne coatings. Full article

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15 pages, 4485 KiB

Open AccessArticle

The Effects of Electron Beam Irradiation on the Morphological and Physicochemical Properties of Magnesium-Doped Hydroxyapatite/Chitosan Composite Coatings

by Bogdan Bita, Elena Stancu, Daniela Stroe, Mirabela Dumitrache, Steluta Carmen Ciobanu, Simona Liliana Iconaru, Daniela Predoi and Andreea Groza

Polymers 2022, 14(3), 582; https://doi.org/10.3390/polym14030582 - 31 Jan 2022

Cited by 18 | Viewed by 3059

Abstract

This work reports on the influence of 5 MeV electron beam radiations on the morphological features and chemical structure of magnesium-doped hydroxyapatite/chitosan composite coatings generated by the magnetron sputtering technique. The exposure to ionizing radiation in a linear electron accelerator dedicated to medical [...] Read more.

This work reports on the influence of 5 MeV electron beam radiations on the morphological features and chemical structure of magnesium-doped hydroxyapatite/chitosan composite coatings generated by the magnetron sputtering technique. The exposure to ionizing radiation in a linear electron accelerator dedicated to medical use has been performed in a controllable manner by delivering up to 50 Gy radiation dose in fractions of 2 Gy radiation dose per 40 s. After the irradiation with electron beams, the surface of layers became nano-size structured. The partial detachment of irradiated layers from the substrates has been revealed only after visualizing their cross sections by scanning electron microscopy. The energy dispersive X-ray spectral analysis of layer cross-sections indicated that the distribution of chemical elements in the samples depends on the radiation dose. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis have shown that the physicochemical processes induced by the ionizing radiation in the magnesium doped hydroxyapatite/chitosan composite coatings do not alter the apatite structure, and Mg remains bonded with the phosphate groups. Full article

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21 pages, 1288 KiB

Open AccessArticle

Characterization of Polyester Coatings Intended for Food Contact by Different Analytical Techniques and Migration Testing by LC-MSⁿ

by Antía Lestido-Cardama, Patricia Vázquez-Loureiro, Raquel Sendón, Juana Bustos, Mª Isabel Santillana, Perfecto Paseiro Losada and Ana Rodríguez Bernaldo de Quirós

Polymers 2022, 14(3), 487; https://doi.org/10.3390/polym14030487 - 26 Jan 2022

Cited by 12 | Viewed by 4677

Abstract

Polymeric coating formulations may contain different components such as cross-linking agents, resins, lubricants, and solvents, among others. If the reaction process or curing conditions are not applied in a proper way, these components may remain unreacted in the polymeric network and could be [...] Read more.

Polymeric coating formulations may contain different components such as cross-linking agents, resins, lubricants, and solvents, among others. If the reaction process or curing conditions are not applied in a proper way, these components may remain unreacted in the polymeric network and could be released and migrate into foods. In this study, several polyester coatings intended for food contact were investigated. Firstly, Fourier-transform infrared spectroscopy with an attenuated total reflectance (ATR-FTIR) spectrometer and confocal Raman microscopy were used to identify the type of coating. Then, different techniques, including gas chromatography coupled to mass spectrometry (GC-MS) and analysis by matrix-assisted laser desorption coupled to time-of-flight mass spectrometry (MALDI-TOF-MS), among others, were used to investigate the potential volatile and non-volatile migrants. Moreover, migration assays were carried out to evaluate the presence of monomers and to tentatively identify possible oligomers below 1000 Da. The analyses were performed by liquid chromatography coupled to ion trap mass spectrometry (LC-MSⁿ). Using the information collected from each analytical technique, it was possible to elucidate some of the starting substances used in the formulation of the polyester coatings analyzed in this study. In migration tests, several polyester oligomers were tentatively identified for which there is not toxicological data available and, therefore, no migration limits established to date. Full article

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17 pages, 4470 KiB

Open AccessArticle

Facile Synthesis of Fluorinated Polysilazanes and Their Durable Icephobicity on Rough Al Surfaces

by Tien N. H. Lo, Sung Woo Hong, Ha Soo Hwang and In Park

Polymers 2022, 14(2), 330; https://doi.org/10.3390/polym14020330 - 14 Jan 2022

Cited by 5 | Viewed by 1801

Abstract

Superhydrophobic Al surfaces with excellent durability and anti-icing properties were fabricated by coating dual-scale rough Al substrates with fluorinated polysilazane (FPSZ). Flat Al plates were etched using an acidic solution, followed by immersion in boiling water to generate hierarchical micro-nano structures on their [...] Read more.

Superhydrophobic Al surfaces with excellent durability and anti-icing properties were fabricated by coating dual-scale rough Al substrates with fluorinated polysilazane (FPSZ). Flat Al plates were etched using an acidic solution, followed by immersion in boiling water to generate hierarchical micro-nano structures on their surfaces. The FPSZ coatings were synthesized by grafting 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17), a fluoroalkyl silane), onto methylpolysilazane, an organopolysilazane (OPSZ) backbone. The high water contact angle (175°) and low sliding angle (1.6°) of the FPSZ-coated sample with an FAS-17 content of 17.3 wt% promoted the efficient removal of a frozen ice column with a low ice adhesion strength of 78 kPa at −20.0 °C (70% relative humidity), which was 4.3 times smaller than that of an OPSZ-coated surface. The FPSZ-coated Al surface suppressed ice nucleation, leading to a decrease in ice nucleation temperature from −19.5 to −21.9 °C and a delay in freezing time from 334 to 4914 s at −19.0 °C compared with the OPSZ-coated Al surface. Moreover, after 40 icing–melting cycles the freezing temperature of a water droplet on the FPSZ-coated Al surface remained unchanged, whereas that on the FAS-17-coated Al surface increased from −22.3 to −20.7 °C. Therefore, the durability of the polymeric FPSZ coating was superior to that of the FAS-17 monolayer coating. Full article

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2021

Jump to: 2023, 2022, 2020, 2019, 2018, 2017

19 pages, 4121 KiB

Open AccessArticle

Preparation of Melamine/Rice Husk Powder Coated Shellac Microcapsules and Effect of Different Rice Husk Powder Content in Wall Material on Properties of Wood Waterborne Primer

by Xiaoxing Yan, Wenbo Li, Yan Han and Taiyu Yin

Polymers 2022, 14(1), 72; https://doi.org/10.3390/polym14010072 - 25 Dec 2021

Cited by 14 | Viewed by 2371

Abstract

The melamine/rice husk powder-coated shellac microcapsules were prepared by in-situ polymerization with melamine resin mixed with rice husk powder as microcapsule wall material and shellac as microcapsule core material. The effect of the addition amount of microcapsules with different wall material ratios on [...] Read more.

The melamine/rice husk powder-coated shellac microcapsules were prepared by in-situ polymerization with melamine resin mixed with rice husk powder as microcapsule wall material and shellac as microcapsule core material. The effect of the addition amount of microcapsules with different wall material ratios on the performance of wood waterborne primer coating was investigated. The results show that the most important factor affecting the performance of microcapsules is the content of rice husk powder. Through the preparation and analysis of shellac microcapsule primer coating coated with melamine/rice husk powder, when the content of microcapsule powder is 0–6%, it has little effect on the optical properties of wood waterborne primer coating, and the microcapsule with 5.5% rice husk powder has little effect on the color difference of primer coating. The coating hardness increases with the increase of rice husk powder content in wall material. When the rice husk powder content in wall material is more than 5.5%, the coating hardness reaches the best. When the content of microcapsule powder is 3.0–9.0%, the adhesion of the coating is better, and the coating with rice husk powder content of 5.5% in microcapsule wall material has better impact resistance. When the content of rice husk powder was 5.5% and the content of microcapsule powder was 6%, the elongation at break of the primer coating was the highest and the tensile resistance was the best. The composition of wood waterborne primer did not change after adding microcapsule. The water-based primer with microcapsule has better aging resistance. The water-based primer coating with rice husk powder content of 5.5% and the addition amount of 6% had the best comprehensive performance, which lays the technical reference for the toughness and self-repairing of the waterborne wood coatings. Full article

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21 pages, 8087 KiB

Open AccessArticle

Mechanism of Thermochromic and Self-Repairing of Waterborne Wood Coatings by Synergistic Action of Waterborne Acrylic Microcapsules and Fluorane Microcapsules

by Xiaoxing Yan, Wenting Zhao and Lin Wang

Polymers 2022, 14(1), 56; https://doi.org/10.3390/polym14010056 - 24 Dec 2021

Cited by 12 | Viewed by 3134

Abstract

The fluorane thermochromic microcapsules and waterborne acrylic resin microcapsules were added into waterborne coatings at the same time to prepare intelligent waterborne coating film with dual functions of color change and self-repairing. The coating film prepared by adding 15.0% fluorane microcapsules and 5.0% [...] Read more.

The fluorane thermochromic microcapsules and waterborne acrylic resin microcapsules were added into waterborne coatings at the same time to prepare intelligent waterborne coating film with dual functions of color change and self-repairing. The coating film prepared by adding 15.0% fluorane microcapsules and 5.0% waterborne acrylic resin microcapsules to the primer at the same time had better comprehensive properties. At this time, the coating film changed from yellow to colorless. The repair rate of the coating film was 58.4%. When the temperature was lower than 32 °C, waterborne acrylic resin microcapsules can improve the thermochromic performance of the coating film with fluorane microcapsules. Waterborne acrylic resin microcapsules can alleviate the color change of coating film with fluorane microcapsules. The fluorane microcapsules can improve the self-repairing performance of coating film with waterborne acrylic resin microcapsules. The results lay a theoretical and technical foundation for multifunctional coating film. Full article

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21 pages, 8857 KiB

Open AccessArticle

Effect of Coating Process on Mechanical, Optical, and Self-Healing Properties of Waterborne Coating on Basswood Surface with MF-Coated Shellac Core Microcapsule

by Yu Tao, Xiaoxing Yan and Yijuan Chang

Polymers 2021, 13(23), 4228; https://doi.org/10.3390/polym13234228 - 02 Dec 2021

Cited by 5 | Viewed by 1581

Abstract

Self-repairing microcapsules prepared with melamine formaldehyde (MF) resin as wall material and shellac and waterborne coating as core material were added to waterborne coating to prepare a self-repairing coating. In order to explore the effect of the coating process on the performance of [...] Read more.

Self-repairing microcapsules prepared with melamine formaldehyde (MF) resin as wall material and shellac and waterborne coating as core material were added to waterborne coating to prepare a self-repairing coating. In order to explore the effect of the coating process on the performance of the waterborne coating on the basswood surface with microcapsules, the number of coating layers of primer and finish and the addition mode of the microcapsules were tested as influencing factors. The effects of different coating processes on the optical, mechanical, and liquid resistance of the basswood surface coating were investigated. The results showed that different coating processes had little effect on the color difference of the coating. When the coating process was two layers of primer and three layers of finish, and microcapsules were added to the finish, the minimum gloss of the basswood surface coating at 60° incident angle was 10.2%, and the best mechanical properties, liquid resistance, and comprehensive properties were achieved. Finally, the aging resistance and self-healing performance of the waterborne coating on the basswood surface prepared by this coating process were explored. The results showed that the waterborne coating had a certain repair effect on scratch damage. This paper lays a theoretical foundation for the practical application of self-healing microcapsules in wood-surface waterborne coatings. Full article

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18 pages, 18172 KiB

Open AccessArticle

Polyamidoamines Derived from Natural α-Amino Acids as Effective Flame Retardants for Cotton

by Alessandro Beduini, Federico Carosio, Paolo Ferruti, Elisabetta Ranucci and Jenny Alongi

Polymers 2021, 13(21), 3714; https://doi.org/10.3390/polym13213714 - 28 Oct 2021

Cited by 13 | Viewed by 2052

Abstract

In this paper, bioinspired polyamidoamines (PAAs) were synthesized from N,N′-methylenebisacrylamide and nine natural α-amino acids: L-alanine, L-valine, L-leucine (M-LEU), L-histidine, L-serine, L-asparagine, L-glutamine (M-GLN), L-aspartic acid and L-glutamic acid (M-GLU) and their performance [...] Read more.

In this paper, bioinspired polyamidoamines (PAAs) were synthesized from N,N′-methylenebisacrylamide and nine natural α-amino acids: L-alanine, L-valine, L-leucine (M-LEU), L-histidine, L-serine, L-asparagine, L-glutamine (M-GLN), L-aspartic acid and L-glutamic acid (M-GLU) and their performance as flame retardants (FRs) for cotton were determined. The aim was to ascertain if the ability to protect cotton from fire by the process of intumescing, previously found for the glycine-derived M-GLY, was a general feature of α-amino acid-derived PAAs. None of the PAAs ignited by flame impingement, apart from M-LEU, which burned for a few seconds leaving 93% of residue. All of them formed carbon- and oxygen-rich, porous chars with a graphitic structure in the air at 350 °C, as revealed by X-ray photoelectron spectroscopy. All samples were tested as FRs for cotton by horizontal flame spread tests. At a 5% add-on, M-GLU and M-GLN extinguished the flame. The same results were obtained with all the other PAAs at a 7% add-on. The α-amino acid residues influenced the FR performance. The most effective were those that, by heating, were most suitable for producing thermally stable cyclic aromatic structures. All PAA-treated cotton samples, even when burning, left significant residues, which, according to scanning electron microscopy analysis, maintained the original cotton texture. Full article

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19 pages, 14975 KiB

Open AccessArticle

RK4 and HAM Solutions of Eyring–Powell Fluid Coating Material with Temperature-Dependent-Viscosity Impact of Porous Matrix on Wire Coating Filled in Coating Die: Cylindrical Co-ordinates

by Zeeshan, Waris Khan, Ilyas Khan, Nawa Alshammari and Nawaf N. Hamadneh

Polymers 2021, 13(21), 3696; https://doi.org/10.3390/polym13213696 - 27 Oct 2021

Cited by 1 | Viewed by 1444

Abstract

In this work, we studied the impacts of transmitting light, nonlinear thermal, and micropolar fluid mechanics on a wire surface coating utilizing non-Newtonian viscoelastic flow. Models with temperature-dependent variable viscosity were used. The boundary layer equations governing the flow and heat transport processes [...] Read more.

In this work, we studied the impacts of transmitting light, nonlinear thermal, and micropolar fluid mechanics on a wire surface coating utilizing non-Newtonian viscoelastic flow. Models with temperature-dependent variable viscosity were used. The boundary layer equations governing the flow and heat transport processes were solved using the Runge–Kutta fourth order method. A distinguished constituent of this study was the use of a porous matrix that acted as an insulator to reduce heat loss. In this paper we discuss the effects of numerous development parameters, including

β_{0}

,

Q, m, Ω, K p

, and

B r

(non-Newtonian parameter, heat-producing parameter, viscosity parameter, variable viscosity parameter, porosity parameter, and Brinkman number, respectively). Furthermore, the effects of two other parameters, D and M, are also discussed as they relate to velocity and temperature distributions. We observed that the velocity profiles decreased with increasing values of

K p

. Fluid velocity increased as the values of

M, B r, N

, and

D

increased, while it decreased when the values of

K p

,

Q

and

D

increased. For increasing values of

M

, the temperature profile showed increasing behavior, while

B r and Q

showed decreasing behavior. Furthermore, the present work is validated by comparison with HAM and previously published work, with good results. Full article

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16 pages, 6192 KiB

Open AccessArticle

Revealing the High-Modulus Mechanism of Polyimide Films Prepared with 3,4′-ODA

by Li Zhu, Yinong Li, Shuhao Han, Hongqing Niu, Dezhen Wu and Shengli Qi

Polymers 2021, 13(18), 3175; https://doi.org/10.3390/polym13183175 - 18 Sep 2021

Cited by 4 | Viewed by 2086

Abstract

To prepare PIs (polyimides) with desirable thermal and mechanical properties is highly demanded due to their widespread applications in flexible optoelectronic devices and printed circuit boards. Here, the PI films of BPDA/4,4′-ODA, BPDA/3,4′-ODA, PMDA/4,4′-ODA, PMDA/3,4′-ODA systems were prepared, and it was found that [...] Read more.

To prepare PIs (polyimides) with desirable thermal and mechanical properties is highly demanded due to their widespread applications in flexible optoelectronic devices and printed circuit boards. Here, the PI films of BPDA/4,4′-ODA, BPDA/3,4′-ODA, PMDA/4,4′-ODA, PMDA/3,4′-ODA systems were prepared, and it was found that the PIs with 3,4′-ODA always exhibit a high modulus compared with the PIs with 4,4′-ODA. To disclose the mechanism of high-modulus PI films with 3,4′-ODA, amorphous PI models and uniaxial drawing PI models were established and calculated based on MD simulation. The PI structural deformations at different length scales, i.e., molecular chain cluster scale and repeat unit scale, under the same stress were detailed and analyzed, including the variation of chain conformation, bond length, bond angle, internal rotation energy, and torsion angle. The results indicate that PIs with 3,4-ODA have higher internal rotation energy and smaller deformation with the same stress, consistent with the high modulus. Full article

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16 pages, 9399 KiB

Open AccessArticle

Environmentally Friendly, High-Performance Fire Retardant Made from Cellulose and Graphite

by Leandra P. Santos, Douglas S. da Silva, Thais H. Morari and Fernando Galembeck

Polymers 2021, 13(15), 2400; https://doi.org/10.3390/polym13152400 - 22 Jul 2021

Cited by 5 | Viewed by 3112

Abstract

Many materials and additives perform well as fire retardants and suppressants, but there is an ever-growing list of unfulfilled demands requiring new developments. This work explores the outstanding dispersant and adhesive performances of cellulose to create a new effective fire-retardant: exfoliated and reassembled [...] Read more.

Many materials and additives perform well as fire retardants and suppressants, but there is an ever-growing list of unfulfilled demands requiring new developments. This work explores the outstanding dispersant and adhesive performances of cellulose to create a new effective fire-retardant: exfoliated and reassembled graphite (ERG). This is a new 2D polyfunctional material formed by drying aqueous dispersions of graphite and cellulose on wood, canvas, and other lignocellulosic materials, thus producing adherent layers that reduce the damage caused by a flame to the substrates. Visual observation, thermal images and surface temperature measurements reveal fast heat transfer away from the flamed spots, suppressing flare formation. Pinewood coated with ERG underwent standard flame resistance tests in an accredited laboratory, reaching the highest possible class for combustible substrates. The fire-retardant performance of ERG derives from its thermal stability in air and from its ability to transfer heat to the environment, by conduction and radiation. This new material may thus lead a new class of flame-retardant coatings based on a hitherto unexplored mechanism for fire retardation and showing several technical advantages: the precursor dispersions are water-based, the raw materials used are commodities, and the production process can be performed on commonly used equipment with minimal waste. Full article

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9 pages, 2279 KiB

Open AccessArticle

Characterization of Low-Density Polyethylene and LDPE-Based/Ethylene-Vinyl Acetate with Medium Content of Vinyl Acetate

by Nga Thi-Hong Pham

Polymers 2021, 13(14), 2352; https://doi.org/10.3390/polym13142352 - 18 Jul 2021

Cited by 13 | Viewed by 7582

Abstract

Low-density polyethylene (LDPE) and ethylene vinyl acetate copolymer (EVA), which are non-polar and polar polymers, are immiscible and form a polyphase system. In this study, LDPE was mixed with 2.5%, 5%, 7.5%, 10%, 12.5% Ethylene-vinyl acetate (EVA-28) with a medium content of vinyl [...] Read more.

Low-density polyethylene (LDPE) and ethylene vinyl acetate copolymer (EVA), which are non-polar and polar polymers, are immiscible and form a polyphase system. In this study, LDPE was mixed with 2.5%, 5%, 7.5%, 10%, 12.5% Ethylene-vinyl acetate (EVA-28) with a medium content of vinyl acetate (28% VA), respectively by injection molding machine and LDPE. Tensile strength and flexural strength were tested according to ASTM D638-02 standard and ISO 178 standard. The results showed that adding EVA-28 increased the elongation at break of the LDPE/2.5% EVA, LDPE/5% EVA and LDPE/10% EVA blend samples. In addition, the tensile and flexural strength of the LDPE/EVA blend decreases gradually as the EVA-28 content in the blend increases. The hardness decreases with the increasing EVA-28 content. EVA-28 spherical particles appeared scattered on the surface of the LDPE matrix, in the highest EVA-28 percent sample (12.5% EVA-28), the number of particles appeared to be quite a lot, and was dispersed quite evenly on the surface. The LDPE/EVA-28 blend achieved a higher elongation at the break than LDPE, in which 10% EVA-28 gives the highest elongation at break. Full article

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16 pages, 10344 KiB

Open AccessEditor’s ChoiceArticle

Simple Preparation of Polydimethylsiloxane and Polyurethane Blend Film for Marine Antibiofouling Application

by Jirasuta Chungprempree, Sutep Charoenpongpool, Jitima Preechawong, Nithi Atthi and Manit Nithitanakul

Polymers 2021, 13(14), 2242; https://doi.org/10.3390/polym13142242 - 08 Jul 2021

Cited by 9 | Viewed by 3562

Abstract

A key way to prevent undesirable fouling of any structure in the marine environment, without harming any microorganisms, is to use a polymer film with high hydrophobicity. The polymer film, which was simply prepared from a blend of hydrophobic polydimethylsiloxane elastomer and hydrophilic [...] Read more.

A key way to prevent undesirable fouling of any structure in the marine environment, without harming any microorganisms, is to use a polymer film with high hydrophobicity. The polymer film, which was simply prepared from a blend of hydrophobic polydimethylsiloxane elastomer and hydrophilic polyurethane, showed improved properties and economic viability for antifouling film for the marine industry. The field emission scanning electron microscope and energy dispersive X-ray spectrometer (FESEM and EDX) results from the polymer blend suggested a homogenous morphology and good distribution of the polyurethane disperse phase. The PDMS:PU blend (95:5) film gave a water contact angle of 103.4° ± 3.8° and the PDMS film gave a water contact angle of 109.5° ± 4.2°. Moreover, the PDMS:PU blend (95:5) film could also be modified with surface patterning by using soft lithography process to further increase the hydrophobicity. It was found that PDMS:PU blend (95:5) film with micro patterning from soft lithography process increased the contact angle to 128.8° ± 1.6°. The results from a field test in the Gulf of Thailand illustrated that the bonding strength between the barnacles and the PDMS:PU blend (95:5) film (0.07 MPa) were lower than the bonding strength between the barnacles and the carbon steel (1.16 MPa). The barnacles on the PDMS:PU blend (95:5) film were more easily removed from the surface. This indicated that the PDMS:PU blend (95:5) exhibited excellent antifouling properties and the results indicated that the PDMS:PU blend (95:5) film with micro patterning surface could be employed for antifouling application. Full article

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3 pages, 145 KiB

Open AccessEditorial

Advances in Polymer Based Composite Coatings

by Andreea Groza

Polymers 2021, 13(10), 1611; https://doi.org/10.3390/polym13101611 - 17 May 2021

Viewed by 1590

Abstract

Polymer based composite coatings represent an important class of materials for various applications [...] Full article

13 pages, 3892 KiB

Open AccessArticle

Improved Measurements of the Physical Properties of Oriental Lacquers Using Atomic Force Microscopy and a Nanoindenter

by Hye Hyun Yu, Jung-Ah Lim, Kang-Bong Lee and Yeonhee Lee

Polymers 2021, 13(9), 1395; https://doi.org/10.3390/polym13091395 - 26 Apr 2021

Cited by 4 | Viewed by 2677

Abstract

Researchers have widely investigated Oriental lacquers to identify the chemical composition and have elucidated corresponding polymerization mechanisms using rigorous analytical techniques. However, researchers generally test the physical properties of Oriental lacquers by conventional methods that are perhaps overly simplistic. Here, we propose accurate [...] Read more.

Researchers have widely investigated Oriental lacquers to identify the chemical composition and have elucidated corresponding polymerization mechanisms using rigorous analytical techniques. However, researchers generally test the physical properties of Oriental lacquers by conventional methods that are perhaps overly simplistic. Here, we propose accurate and quantitative methods for evaluating the physical properties of Korean, Vietnamese, and Myanmarese lacquer films using atomic force microscopy (AFM), a nanoindenter, and a 90° peel tester. We obtained surface images of the lacquers in accordance with drying time using scanning electron microscopy and AFM. The Korean lacquer film exhibited fast hardening speed, enhanced hardness, and strong adhesion strength compared with the other lacquers, although the Myanmarese lacquer film had a smoother surface than the Korean lacquer film. We used our characterization approach for evaluating a mixed Korean/Myanmarese (50/50 w/w) lacquer. Our proposed measurement techniques for Oriental lacquer films provided results that agreed with qualitative results from conventional tests. Force–distance curves in AFM and force–displacement with nanoindenter for Oriental lacquer films showed more accurate and quantitative data on the mechanical properties. Thus, researchers will find our approach useful when they optimize the chemical compositions and improve the physical properties of Oriental lacquer films for industrial applications. Full article

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21 pages, 7549 KiB

Open AccessReview

Overview of Silica-Polymer Nanostructures for Waterborne High-Performance Coatings

by Tiago D. Martins, Tânia Ribeiro and José Paulo S. Farinha

Polymers 2021, 13(7), 1003; https://doi.org/10.3390/polym13071003 - 24 Mar 2021

Cited by 6 | Viewed by 3692

Abstract

Combining organic and inorganic components at a nanoscale is an effective way to obtain high performance coating materials with excellent chemical and physical properties. This review focuses on recent approaches to prepare hybrid nanostructured waterborne coating materials combining the mechanical properties and versatility [...] Read more.

Combining organic and inorganic components at a nanoscale is an effective way to obtain high performance coating materials with excellent chemical and physical properties. This review focuses on recent approaches to prepare hybrid nanostructured waterborne coating materials combining the mechanical properties and versatility of silica as the inorganic filler, with the flexural properties and ease of processing of the polymer matrix. We cover silica-polymer coupling agents used to link the organic and inorganic components, the formation of hybrid films from these silica-polymer nanostructures, and their different applications. These hybrid nanostructures can be used to prepare high performance functional coatings with different properties from optical transparency, to resistance to temperature, hydrophobicity, anti-corrosion, resistance to scratch, and antimicrobial activity. Full article

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19 pages, 2033 KiB

Open AccessReview

Mechanical Properties of Protective Coatings against Marine Fouling: A Review

by Alessandro Pistone, Cristina Scolaro and Annamaria Visco

Polymers 2021, 13(2), 173; https://doi.org/10.3390/polym13020173 - 06 Jan 2021

Cited by 61 | Viewed by 7892

Abstract

The accumulation of marine organisms on ship hulls, such as microorganisms, barnacles, and seaweeds, represents a global problem for maritime industries, with both economic and environmental costs. The use of biocide-containing paints poses a serious threat to marine ecosystems, affecting both target and [...] Read more.

The accumulation of marine organisms on ship hulls, such as microorganisms, barnacles, and seaweeds, represents a global problem for maritime industries, with both economic and environmental costs. The use of biocide-containing paints poses a serious threat to marine ecosystems, affecting both target and non-target organisms driving science and technology towards non-biocidal solutions based on physico-chemical and materials properties of coatings. The review reports recent development of hydrophobic protective coatings in terms of mechanical properties, correlated with the wet ability features. The attention is focused mainly on coatings based on siloxane and epoxy resin due to the wide application fields of such systems in the marine industry. Polyurethane and other systems have been considered as well. These coatings for anti-fouling applications needs to be both long-term mechanically stable, perfectly adherent with the metallic/composite substrate, and capable to detach/destroy the fouling organism. Prospects should focus on developing even “greener” antifouling coatings solutions. These coatings should also be readily addressable to industrial scale-up for large-scale product distribution, possibly at a reasonable cost. Full article

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2020

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14 pages, 8947 KiB

Open AccessArticle

Chitosan–Hydroxyapatite Composite Layers Generated in Radio Frequency Magnetron Sputtering Discharge: From Plasma to Structural and Morphological Analysis of Layers

by Dragana Biliana Dreghici, Bogdan Butoi, Daniela Predoi, Simona Liliana Iconaru, Ovidiu Stoican and Andreea Groza

Polymers 2020, 12(12), 3065; https://doi.org/10.3390/polym12123065 - 21 Dec 2020

Cited by 15 | Viewed by 2823

Abstract

Chitosan–hydroxyapatite composite layers were deposited on Si substrates in radio frequency magnetron sputtering discharges. The plasma parameters calculated from the current–voltage radio frequency-compensated Langmuir probe characteristics indicate a huge difference between the electron temperature in the plasma and at the sample holder. These [...] Read more.

Chitosan–hydroxyapatite composite layers were deposited on Si substrates in radio frequency magnetron sputtering discharges. The plasma parameters calculated from the current–voltage radio frequency-compensated Langmuir probe characteristics indicate a huge difference between the electron temperature in the plasma and at the sample holder. These findings aid in the understanding of the coagulation pattern of hydroxyapatite–chitosan macromolecules on the substrate surface. An increase in the sizes of the spherical-shape grain-like structures formed on the coating surface with the plasma electron number density was observed. The link between the chemical composition of the chitosan–hydroxyapatite composite film and the species sputtered from the target or produced by excitation/ionization mechanisms in the plasma was determined on the basis of X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and residual gas mass spectrometry analysis. Full article

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9 pages, 2688 KiB

Open AccessArticle

Triboelectric Energy Harvesting of the Superhydrophobic Coating from Dropping Water

by Jiaxuan Niu, Wenjie Xu, Kaiyi Tian, Gang He, Zhengyong Huang and Qiang Wang

Polymers 2020, 12(9), 1936; https://doi.org/10.3390/polym12091936 - 27 Aug 2020

Cited by 17 | Viewed by 3578

Abstract

In this paper, the superhydrophobic coating was prepared by spraying the composites of fluorocarbon emulsion and nanosized silica on the conductive glass sheet for the triboelectric energy harvesting from water droplets. The low surface energy of fluorine in the fluorocarbon emulsion and nanosilica [...] Read more.

In this paper, the superhydrophobic coating was prepared by spraying the composites of fluorocarbon emulsion and nanosized silica on the conductive glass sheet for the triboelectric energy harvesting from water droplets. The low surface energy of fluorine in the fluorocarbon emulsion and nanosilica renders the coating with the static contact angle and sliding angle of 156.2° and 6.74°, respectively. The conductive aluminum tape was attached on the surface of the superhydrophobic coating to complete the circuit constituted with the aluminum electrode, charged superhydrophobic coating, and the conductive glass sheet. During the contact electrification with the bouncing water droplet, the superhydrophobic coating with the aluminum electrode can obtain the electric energy with an open-circuit voltage of 20 V and short-circuit current of 4.5 μA, respectively. While the control device only produced an open-circuit voltage of 0.2 V. The generated power by one drop was enough to light up 16 commercial LEDs. Results demonstrate that the fluorocarbon/silica composite superhydrophobic coating is potentially a strong candidate for scavenging energy in sliding mode from raindrops. Full article

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14 pages, 3990 KiB

Open AccessArticle

A Green Approach to Modify Surface Properties of Polyurethane Foam for Enhanced Oil Absorption

by Zhi Chien Ng, Rosyiela Azwa Roslan, Woei Jye Lau, Mehmet Gürsoy, Mustafa Karaman, Nora Jullok and Ahmad Fauzi Ismail

Polymers 2020, 12(9), 1883; https://doi.org/10.3390/polym12091883 - 21 Aug 2020

Cited by 18 | Viewed by 3612

Abstract

The non-selective property of conventional polyurethane (PU) foam tends to lower its oil absorption efficiency. To address this issue, we modified the surface properties of PU foam using a rapid solvent-free surface functionalization approach based on the chemical vapor deposition (CVD) method to [...] Read more.

The non-selective property of conventional polyurethane (PU) foam tends to lower its oil absorption efficiency. To address this issue, we modified the surface properties of PU foam using a rapid solvent-free surface functionalization approach based on the chemical vapor deposition (CVD) method to establish an extremely thin yet uniform coating layer to improve foam performance. The PU foam was respectively functionalized using different monomers, i.e., perfluorodecyl acrylate (PFDA), 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA), and hexamethyldisiloxane (HMDSO), and the effect of deposition times (1, 5 and 10 min) on the properties of foam was investigated. The results showed that all the modified foams demonstrated a much higher water contact angle (i.e., greater hydrophobicity) and greater absorption capacities compared to the control PU foam. This is due to the presence of specific functional groups, e.g., fluorine (F) and silane (Si) in the modified PU foams. Of all, the PU/PHFBA_i foam exhibited the highest absorption capacities, recording 66.68, 58.15, 53.70, and 58.38 g/g for chloroform, acetone, cyclohexane, and edible oil, respectively. These values were 39.19–119.31% higher than that of control foam. The promising performance of the PU/PHFBA_i foam is due to the improved surface hydrophobicity attributed to the original perfluoroalkyl moieties of the HFBA monomer. The PU/PHFBA_i foam also demonstrated a much more stable absorption performance compared to the control foam when both samples were reused for up to 10 cycles. This clearly indicates the positive impact of the proposed functionalization method in improving PU properties for oil absorption processes. Full article

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22 pages, 2243 KiB

Open AccessArticle

Reduction of Postharvest Quality Loss and Microbiological Decay of Tomato “Chonto” (Solanum lycopersicum L.) Using Chitosan-E Essential Oil-Based Edible Coatings under Low-Temperature Storage

by Yeimmy Peralta-Ruiz, Carlos David Grande Tovar, Angie Sinning-Mangonez, Edgar A. Coronell, Marcos F. Marino and Clemencia Chaves-Lopez

Polymers 2020, 12(8), 1822; https://doi.org/10.3390/polym12081822 - 13 Aug 2020

Cited by 39 | Viewed by 4983

Abstract

The tomato (Solanum lycopersicum L.) is one of the many essential vegetables around the world due to its nutritive content and attractive flavor. However, its short shelf-life and postharvest losses affect its marketing. In this study, the effects of chitosan-Ruta graveolens [...] Read more.

The tomato (Solanum lycopersicum L.) is one of the many essential vegetables around the world due to its nutritive content and attractive flavor. However, its short shelf-life and postharvest losses affect its marketing. In this study, the effects of chitosan-Ruta graveolens (CS + RGEO) essential oil coatings on the postharvest quality of Tomato var. “chonto” stored at low temperature (4 °C) for 12 days are reported. The film-forming dispersions (FFD) were eco-friendly synthesized and presented low viscosities (between 0.126 and 0.029 Pa s), small particle sizes (between 1.29 and 1.56 μm), and low densities. The mature index (12.65% for uncoated fruits and 10.21% for F4 coated tomatoes), weight loss (29.8% for F1 and 16.7% for F5 coated tomatoes), and decay index (3.0 for uncoated and 1.0 for F5 coated tomatoes) were significantly different, indicating a preservative effect on the quality of the tomato. Moreover, aerobic mesophilic bacteria were significantly reduced (in five Log CFU/g compared to control) by using 15 μL/mL of RGEO. The coatings, including 10 and 15 μL/mL of RGEO, completely inhibited the mold and yeast growth on tomato surfaces without negatively affecting the consumer acceptation, as the sensorial analysis demonstrated. The results presented in this study show that CS + RGEO coatings are promising in the postharvest treatment of tomato var. “chonto”. Full article

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22 pages, 2863 KiB

Open AccessArticle

A Refined Theory for Characterizing Adhesion of Elastic Coatings on Rigid Substrates Based on Pressurized Blister Test Methods: Closed-Form Solution and Energy Release Rate

by Yong-Sheng Lian, Jun-Yi Sun, Zhi-Hang Zhao, Shou-Zhen Li and Zhou-Lian Zheng

Polymers 2020, 12(8), 1788; https://doi.org/10.3390/polym12081788 - 10 Aug 2020

Cited by 13 | Viewed by 2060

Abstract

Adhesion between coatings and substrates is an important parameter determining the integrity and reliability of film/substrate systems. In this paper, a new and more refined theory for characterizing adhesion between elastic coatings and rigid substrates is developed based on a previously proposed pressurized [...] Read more.

Adhesion between coatings and substrates is an important parameter determining the integrity and reliability of film/substrate systems. In this paper, a new and more refined theory for characterizing adhesion between elastic coatings and rigid substrates is developed based on a previously proposed pressurized blister method. A compressed air driven by liquid potential energy is applied to the suspended circular coating film through a circular hole in the substrate, forcing the suspended film to bulge, and then to debond slowly from the edge of the hole as the air pressure intensifies, and finally to form a blister with a certain circular delamination area. The problem from the initially flat coating to the stable blistering film under a prescribed pressure is simplified as a problem of axisymmetric deformation of peripherally fixed and transversely uniformly loaded circular membranes. The adhesion strength depends on the delamination area and is quantified in terms of the energy released on per unit delamination area, the so-called energy release rate. In the present work, the problem of axisymmetric deformation is reformulated with out-of-plane and in-plane equilibrium equations and geometric equations, simultaneously improved, and a new closed-form solution is presented, resulting in the new and more refined adhesion characterization theory. Full article

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16 pages, 6461 KiB

Open AccessArticle

Novel Low-Temperature Chemical Vapor Deposition of Hydrothermal Delignified Wood for Hydrophobic Property

by Rui Yang, Yunyi Liang, Shu Hong, Shida Zuo, Yingji Wu, Jiangtao Shi, Liping Cai, Jianzhang Li, Haiyan Mao, Shengbo Ge and Changlei Xia

Polymers 2020, 12(8), 1757; https://doi.org/10.3390/polym12081757 - 06 Aug 2020

Cited by 20 | Viewed by 3926

Abstract

As a hydrophilic material, wood is difficult to utilize for external applications due to the variable weather conditions. In this study, an efficient, facile, and low-cost method was developed to enhance the hydrophobicity of wood. By applying the low-temperature chemical vapor deposition (CVD) [...] Read more.

As a hydrophilic material, wood is difficult to utilize for external applications due to the variable weather conditions. In this study, an efficient, facile, and low-cost method was developed to enhance the hydrophobicity of wood. By applying the low-temperature chemical vapor deposition (CVD) technology, the polydimethylsiloxane-coated wood (PDMS@wood) with hydrophobic surface was fabricated employing dichlorodimethylsilane as the CVD chemical resource. The result of water contact angle (i.e., 157.3°) revealed the hydrophobic behavior of the PDMS@wood. The microstructures of the wood samples were observed by scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) analysis verified PDMS successfully coated on wood surfaces. The chemical functional groups of the PDMS@wood were investigated by Fourier transform infrared (FT-IR) and Raman spectra. The thermogravimetric results indicated the enhanced thermal stability of the wood after PDMS coating. In addition, the stability test of PDMS@wood indicated that the hydrophobicity properties of the PDMS@wood samples were preserved after long-time storage (e.g., 30 days). The scratch test was carried out to examine the abrasion resistance of the hydrophobic coatings on PDMS@wood surface. It was suggested that low-temperature CVD process could be a successful approach for fabricating hydrophobic wood. Full article

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19 pages, 3591 KiB

Open AccessArticle

Removal and Oxidation of As(III) from Water Using Iron Oxide Coated CTAB as Adsorbent

by Daniela Predoi, Simona Liliana Iconaru, Mihai Valentin Predoi and Mikael Motelica-Heino

Polymers 2020, 12(8), 1687; https://doi.org/10.3390/polym12081687 - 29 Jul 2020

Cited by 18 | Viewed by 3263

Abstract

Iron oxides such as magnetite and maghemite coated with cetyltrimethylammonium bromide (CTAB) are very promising materials for wastewater treatment because iron oxide can be easily separated from solutions using the magnetic separation procedure Iron oxide (IO) coated CTAB was synthesized by an adapted [...] Read more.

Iron oxides such as magnetite and maghemite coated with cetyltrimethylammonium bromide (CTAB) are very promising materials for wastewater treatment because iron oxide can be easily separated from solutions using the magnetic separation procedure Iron oxide (IO) coated CTAB was synthesized by an adapted co-precipitation method. In the present study, the IO-CTAB was used for removing arsenic from water for the first time. In the present study, the performance of iron oxide coated CTAB biocomposites as an adsorbent for arsenic removal from aqueous solutions was examined. X-ray diffraction (XRD) analysis and the results revealed a cubic phase Fd-3 m of Fe₃O₄ with lattice a = 8.40 Å and average crystal size equal to 17.26 ± 3 nm. The mean particle size calculated from transmission electron microscopy (TEM) was 19.86 ±1.7 nm. The results of the adsorption batch experiments and the data determined using the Langmuir and Freundlich models emphasized that IO-CTAB nanoparticles were favorable for the adsorption of As(III) ions from aqueous solutions. Ultrasound measurements have shown that IO-CTAB is a cost-effective biocomposite for removing arsenic from contaminated solutions. Moreover, x-ray photoelectron spectroscopy (XPS) has shown that during the process of arsenic absorption, there is oxidation from As(III) to As(V), which leads to a decrease in toxicity during this process. The results of the cytotoxic assays confirmed that the IO-CTAB nanoparticles did not induce any morphological changes in the HeLa cells and did not affect their proliferation after 24 h of incubation. Full article

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14 pages, 4025 KiB

Open AccessArticle

Combining Fluorinated Polymers with Ag Nanoparticles as a Route to Enhance Optical Properties of Composite Materials

by Veronica Satulu, Bogdana Mitu, Valentin Ion, Valentina Marascu, Elena Matei, Cristian Stancu and Gheorghe Dinescu

Polymers 2020, 12(8), 1640; https://doi.org/10.3390/polym12081640 - 23 Jul 2020

Cited by 12 | Viewed by 3301

Abstract

Polymer-based nanocomposites have recently received considerable attention due to their unique properties, which makes them feasible for applications in optics, sensors, energy, life sciences, etc. The present work focuses on the synthesis of nanocomposites consisting of a polytetrafluorethylene-like matrix in which metallic nano-silver [...] Read more.

Polymer-based nanocomposites have recently received considerable attention due to their unique properties, which makes them feasible for applications in optics, sensors, energy, life sciences, etc. The present work focuses on the synthesis of nanocomposites consisting of a polytetrafluorethylene-like matrix in which metallic nano-silver are embedded, by using multiple magnetron plasmas. By successively exposing the substrate to separate RF magnetrons using as combination of target materials polytetrafluorethylene (PTFE) and silver, individual control of each deposition process is insured, allowing obtaining of structures in which silver nanoparticles are entrapped in-between two PTFE layers with given thicknesses. The topographical and morphological characteristics investigated by means of Scanning Electron Microscopy and Atomic Force Microscopy techniques evidenced the very presence of Ag nanoparticles with typical dimension 7 nm. The chemical composition at various depositing steps was evaluated through X-ray Photoelectron Spectroscopy. We show that the presence of the top PTFE layer prevents silver oxidation, while its thickness allows the tailoring of optical properties, as evidenced by spectroellipsometry. The appearance of chemical bonds between silver atoms and PTFE atoms at interfaces is observed, pointing out that despite of pure physical deposition processes, a chemical interaction between the polymeric matrix and metal is promoted by plasma. Full article

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22 pages, 3067 KiB

Open AccessReview

Polyurethane/Zinc Oxide (PU/ZnO) Composite—Synthesis, Protective Property and Application

by Mohammad Mizanur Rahman

Polymers 2020, 12(7), 1535; https://doi.org/10.3390/polym12071535 - 11 Jul 2020

Cited by 50 | Viewed by 8873

Abstract

A polyurethane (PU) is a multifunctional polymer prepared by using more than two types of monomers. The unique properties of PU come from monomers, thus broadening the applicability of PU in many different sectors. The properties can be further improved by using many [...] Read more.

A polyurethane (PU) is a multifunctional polymer prepared by using more than two types of monomers. The unique properties of PU come from monomers, thus broadening the applicability of PU in many different sectors. The properties can be further improved by using many nanoparticles. Different metal oxides as nanoparticles are also widely used in PU materials. ZnO is a widely used inorganic metal oxide nanoparticle for improving polymer properties. In this review article, the techniques to prepare a PU/ZnO composite are reviewed; the key protective properties, such as adhesive strength and self-healing, and applications of PU/ZnO composites are also highlighted. This review also highlights the PU/ZnO composite’s current challenges and future prospects, which will help to broaden the composite practical application by preparing environmentally friendly composites. Full article

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15 pages, 3931 KiB

Open AccessReview

Polymer Brush Coating and Adhesion Technology at Scale

by Kristian Birk Buhl, Asger Holm Agergaard, Mie Lillethorup, Jakob Pagh Nikolajsen, Steen Uttrup Pedersen and Kim Daasbjerg

Polymers 2020, 12(7), 1475; https://doi.org/10.3390/polym12071475 - 30 Jun 2020

Cited by 16 | Viewed by 8058

Abstract

Creating strong joints between dissimilar materials for high-performance hybrid products places high demands on modern adhesives. Traditionally, adhesion relies on the compatibility between surfaces, often requiring the use of primers and thick bonding layers to achieve stable joints. The coatings of polymer brushes [...] Read more.

Creating strong joints between dissimilar materials for high-performance hybrid products places high demands on modern adhesives. Traditionally, adhesion relies on the compatibility between surfaces, often requiring the use of primers and thick bonding layers to achieve stable joints. The coatings of polymer brushes enable the compatibilization of material surfaces through precise control over surface chemistry, facilitating strong adhesion through a nanometer-thin layer. Here, we give a detailed account of our research on adhesion promoted by polymer brushes along with examples from industrial applications. We discuss two fundamentally different adhesive mechanisms of polymer brushes, namely (1) physical bonding via entanglement and (2) chemical bonding. The former mechanism is demonstrated by e.g., the strong bonding between poly(methyl methacrylate) (PMMA) brush coated stainless steel and bulk PMMA, while the latter is shown by e.g., the improved adhesion between silicone and titanium substrates, functionalized by a hydrosilane-modified poly(hydroxyethyl methacrylate) (PHEMA) brush. This review establishes that the clever design of polymer brushes can facilitate strong bonding between metals and various polymer materials or compatibilize fillers or nanoparticles with otherwise incompatible polymeric matrices. To realize the full potential of polymer brush functionalized materials, we discuss the progress in the synthesis of polymer brushes under ambient and scalable industrial conditions, and present recent developments in atom transfer radical polymerization for the large-scale production of brush-modified materials. Full article

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12 pages, 3358 KiB

Open AccessArticle

Fabrication of Robust Superhydrophobic Surfaces with Dual-Curing Siloxane Resin and Controlled Dispersion of Nanoparticles

by Hyeran Kim, Kibeom Nam and Dong Yun Lee

Polymers 2020, 12(6), 1420; https://doi.org/10.3390/polym12061420 - 25 Jun 2020

Cited by 18 | Viewed by 3833

Abstract

We developed a simple method for the fabrication of superhydrophobic surfaces on various substrates using spray coating. The fabrication method started with the blending of a modified hydrophobic siloxane binder, silica nanoparticles, and a volatile solvent by sonication. The mixture was spray-coated on [...] Read more.

We developed a simple method for the fabrication of superhydrophobic surfaces on various substrates using spray coating. The fabrication method started with the blending of a modified hydrophobic siloxane binder, silica nanoparticles, and a volatile solvent by sonication. The mixture was spray-coated on various surfaces such as slide glass, paper, metal and fabric, forming a rough surface comprising silica particles dispersed in a hydrophobic binder. Surface hydrophobicity was affected by the surface energy of the binder and the degree of roughness. Therefore, we realized a superhydrophobic surface by controlling these two factors. The hydrophobicity of the siloxane binder was determined by the treatment of fluorine silane; the roughness was controlled by the amount of coated materials and sonication time. Thus, using the spray coating method, we obtained a superhydrophobic surface that was mechanically durable, thermally stable, and chemically resistant. Full article

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12 pages, 7133 KiB

Open AccessArticle

Preparation of Electrosprayed, Microporous Particle Filled Layers

by Mohanapriya Venkataraman, Kai Yang, Xiaoman Xiong, Jiri Militky, Dana Kremenakova, Guocheng Zhu, Juming Yao, Yan Wang and Guoqing Zhang

Polymers 2020, 12(6), 1352; https://doi.org/10.3390/polym12061352 - 15 Jun 2020

Cited by 7 | Viewed by 2391

Abstract

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer known for its excellent hydrophobic properties. In this work, samples from PTFE dispersions with different combinations of water and carbon microparticles were prepared using an electrospraying method. The morphologies and sizes of carbon particles were investigated and [...] Read more.

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer known for its excellent hydrophobic properties. In this work, samples from PTFE dispersions with different combinations of water and carbon microparticles were prepared using an electrospraying method. The morphologies and sizes of carbon particles were investigated and the properties of layers including roughness, hydrophobicity and electrical resistivity were investigated. The non-conductive carbon microparticles were selected as a model particle to check the compatibility and electrospraying ability, and it had no effect on the hydrophobic and electrical properties. Carbon microparticles in polymer solution increased the degree of ionization and was found to be beneficial for the shape control of materials. The results showed that PTFE dispersion with the composition of water and carbon microparticles produced fine sphere particles and the layer fabricated with increased roughness. It was also found that the electrical resistivity and hydrophobicity of all the layers comparatively increased. The fabricated microporous layers can be used in various applications like interlining layer in multilayer textile sandwiches. Full article

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16 pages, 2830 KiB

Open AccessArticle

The Effect of Poly(ethylene glycol) (PEG) Length on the Wettability and Surface Chemistry of PEG-Fluoroalkyl-Modified Polystyrene Diblock Copolymers and Their Two-Layer Films with Elastomer Matrix

by Elisa Guazzelli, Giancarlo Galli and Elisa Martinelli

Polymers 2020, 12(6), 1236; https://doi.org/10.3390/polym12061236 - 29 May 2020

Cited by 11 | Viewed by 3282

Abstract

Diblock copolymers composed of a polystyrene first block and a PEG-fluoroalkyl chain-modified polystyrene second block were synthesized by controlled atom transfer radical polymerization (ATRP), starting from the same polystyrene macroinitiator. The wettability of the polymer film surfaces was investigated by measurements of static [...] Read more.

Diblock copolymers composed of a polystyrene first block and a PEG-fluoroalkyl chain-modified polystyrene second block were synthesized by controlled atom transfer radical polymerization (ATRP), starting from the same polystyrene macroinitiator. The wettability of the polymer film surfaces was investigated by measurements of static and dynamic contact angles. An increase in advancing water contact angle was evident for all the films after immersion in water for short times (10 and 1000 s), consistent with an unusual contraphilic switch of the PEG-fluoroalkyl side chains. Such a contraphilic response also accounted for the retained wettability of the polymer films upon prolonged contact with water, without an anticipated increase in the hydrophilic character. The copolymers were then used as surface-active modifiers of elastomer poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)-based two-layer films. The elastomeric behavior of the films was varied by using SEBS matrices with different amounts of polystyrene. Whereas the mechanical properties strictly resembled those of the nature of the SEBS matrix, the surface properties were imposed by the additive. The contraphilic switch of the PEG-fluoroalkyl side chains resulted in an exceptionally high enrichment in fluorine of the film surface after immersion in water for seven days. Full article

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14 pages, 3822 KiB

Open AccessArticle

Synthesis and Application of a Cationic Polyamine as Yankee Dryer Coating Agent for the Tissue Paper-Making Process

by Cesar Valencia, Yamid Valencia and Carlos David Grande Tovar

Polymers 2020, 12(1), 173; https://doi.org/10.3390/polym12010173 - 09 Jan 2020

Cited by 10 | Viewed by 6623

Abstract

Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the [...] Read more.

Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the paper to the yankee dryer (creping cylinder) in paper manufacture. Nevertheless, these resins are highly cationic and they normally adhere in excess to the paper which negatively affects the creping process and the quality of the paper. For this reason, a low cationic polyamine-epichlorohydrin coating (Polycoat 38^®) was synthesized from a diamine supplied by Disproquin S.A.S. and epichlorohydrin. The analysis of the synthesized polymer was carried out by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H-NMR). The molecular weight of the polymer was obtained by gel permeation chromatography (GPC), physical-chemical properties such as kinematic viscosity, percentage of solids, density, charge density were measured and compared with a commercial PAE resin (Dispro620^®) Thermal stability of the Polycoat 38^® and glass transition temperature in presence of a release agent (Disprosol 17^®) were also evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Finally, a peel adhesion test and an absorption durability assessment were carried out together with the evaluation of the creeping efficiency of the paper by caliber and tensile measurements in a tissue (towel paper) production plant, demonstrating a superior performance in the paper creping process as compared to some commercially available products. Full article

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2019

Jump to: 2023, 2022, 2021, 2020, 2018, 2017

18 pages, 3021 KiB

Open AccessArticle

GC-MS Screening for the Identification of Potential Migrants Present in Polymeric Coatings of Food Cans

by Antía Lestido Cardama, Raquel Sendón, Juana Bustos, M. Isabel Santillana, Perfecto Paseiro Losada and Ana Rodríguez Bernaldo de Quirós

Polymers 2019, 11(12), 2086; https://doi.org/10.3390/polym11122086 - 13 Dec 2019

Cited by 25 | Viewed by 5316

Abstract

The coatings used in cans can release complex chemical mixtures into foodstuffs. Therefore, it is important to develop analytical methods for the identification of these potential migrant compounds in packaged food to guarantee the compliance with European food packaging legislation and ensure consumer [...] Read more.

The coatings used in cans can release complex chemical mixtures into foodstuffs. Therefore, it is important to develop analytical methods for the identification of these potential migrant compounds in packaged food to guarantee the compliance with European food packaging legislation and ensure consumer safety. In the present work, the type of coating in a total of twelve cans collected in Santiago de Compostela (Spain) were evaluated using an ATR (attenuated total reflectance)-FTIR spectrometer. These samples were analysed after extraction with acetonitrile in order to identify potential migrants through a screening method by gas chromatography coupled to mass spectrometry (GC-MS). A total of forty-seven volatile and semi-volatile compounds were identified in these samples, including plasticizers, photoinitiators, antioxidants, lubricants, etc. Then, in a second step, a targeted analysis was carried out for the simultaneous determination of 13 compounds, including bisphenols (BPA, BPB, BPC, BPE, BPF, BPG) and BADGEs (BADGE, BADGE.H₂O, BADGE.2H₂O, BADGE.HCl, BADGE.2HCl, BADGE.H₂O.HCl, cyclo-di-BADGE) by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with atmospheric pressure chemical ionisation (APCI) source. Among all the bisphenols analysed, only the bisphenol A was detected in four samples; while cyclo-di-BADGE was the predominant compound detected in all the samples analysed. Full article

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13 pages, 2627 KiB

Open AccessArticle

Production and Characterization of Glutathione-Chitosan Conjugate Films as Systems for Localized Release of Methotrexate

by Yhors Ciro, John Rojas, Cristian J. Yarce and Constain H. Salamanca

Polymers 2019, 11(12), 2032; https://doi.org/10.3390/polym11122032 - 07 Dec 2019

Cited by 5 | Viewed by 3052

Abstract

Cancer is one of the most serious public health problems that affect humanity. Diverse delivery systems of anticancer drugs have been developed to enhance the treatment effectiveness and patient compliance. Thus, drug delivery systems from polymeric films could be an interesting and promising [...] Read more.

Cancer is one of the most serious public health problems that affect humanity. Diverse delivery systems of anticancer drugs have been developed to enhance the treatment effectiveness and patient compliance. Thus, drug delivery systems from polymeric films could be an interesting and promising alternative, especially for skin chemotherapeutics. In this work, polymeric films based on glutathione-chitosan conjugates with degrees of thiolation of 4.4%, 5.1% and 7.0% were synthetized by casting-evaporation method and subsequent loading with methotrexate. The surface properties of these films were evaluated by contact angle and spreading rate measurements. The sessile drop methods along with the thermodynamic parameter of work of adhesion were determined using the Young–Dupré semi-empirical model. The in vitro methotrexate release was assessed at a pH of 4.5 and 7.4 simulating physiological conditions. Data from the resulting profiles were fitted to the order one, Higuchi, Peppas–Sahlin and Korsmeyer–Peppas kinetic models. The results suggest a strong relationship between the thiolation degree and hydrophilic surface properties such as contact angle and water spreading rate, whereas the work of adhesion was not significantly affected. Further, these polymer films could control the methotrexate release through diverse mechanisms such as diffusion and relaxation depending on the thiolation degree and the aqueous medium employed. In fact, as thiolation degree increased, the release mechanism shifted from a primary diffusional type towards a predominant relaxation-driven mechanism. These polymer films could be used as modified systems for anticancer local delivery. Full article

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20 pages, 4898 KiB

Open AccessArticle

The Influence of Spraying Strategy on the Dynamic Response of Polyurea-Coated Metal Plates to Localized Air Blast Loading: Experimental Investigations

by Yongqing Li, Changhai Chen, Hailiang Hou, Yuansheng Cheng, Haopeng Gao, Pan Zhang and Ting Liu

Polymers 2019, 11(11), 1888; https://doi.org/10.3390/polym11111888 - 15 Nov 2019

Cited by 25 | Viewed by 3146

Abstract

Polyurea has attracted considerable attention owing to its potential applications in protective fields to improve the resistant performance of structures subjected to damage loads resulting from intentional or accidental explosions. However, different spraying strategies of polyurea may lead to significant differences in overall [...] Read more.

Polyurea has attracted considerable attention owing to its potential applications in protective fields to improve the resistant performance of structures subjected to damage loads resulting from intentional or accidental explosions. However, different spraying strategies of polyurea may lead to significant differences in overall resistance performance of polyurea-coated structures, and the underlying mechanisms have not been clear until now. This study aims to elucidate the influence of spraying strategy, i.e., spraying area, spraying thickness, and spraying interface condition, on the dynamic response of polyurea-coated steel plates under localized air blast loading. Three types of plates manufactured using different spraying strategies were adopted to evaluate their blast-resistant performance. The spraying strategies used were (i) whole-area spraying, (ii) partial-area spraying, and (iii) in-contact backing of polyurea on the rear surfaces of steel plates. In addition, the influence of spraying thickness of polyurea for whole-area sprayed plates was evaluated. The energy absorbing mechanisms of polyurea backing layers were highlighted. The energy absorption of plates was quantitatively analyzed. The results show that the air blast resistances of whole-area sprayed and in-contact backed plates are both superior to, whereas that of partial-area sprayed plates is inferior to, bare steel counterparts. A suitable spraying thickness of polyurea can significantly reduce the damage of the front steel layer, whereas excessive spraying thickness decreases the overall air blast resistance of plates. The polyurea backing layer exhibits favorable performance in absorbing energy under a whole-area spraying condition. This study provides useful guidance for the design of polyurea-coated metal plates in engineering applications. Full article

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14 pages, 4583 KiB

Open AccessArticle

Synthesis of a Novel Linear α, ω-Di (Chloro Phosphoramide) Polydimethylsiloxane and Its Applications in Improving Flame-Retardant and Water-Repellent Properties of Cotton Fabrics

by Chaohong Dong, Ling Sun, Xingbo Ma, Zhou Lu, Pengshuang He and Ping Zhu

Polymers 2019, 11(11), 1829; https://doi.org/10.3390/polym11111829 - 07 Nov 2019

Cited by 24 | Viewed by 2656

Abstract

A novel linear α, ω-di (chloro phosphoramide)-terminated polydimethylsiloxane (CPN-PDMS) was successfully synthesized and utilized as a formaldehyde-free water-repellent and flame-retardant for cotton fabrics. The flame retardancy of treated cotton fabrics was estimated by limiting oxygen index (LOI) test, vertical flammability test, and cone [...] Read more.

A novel linear α, ω-di (chloro phosphoramide)-terminated polydimethylsiloxane (CPN-PDMS) was successfully synthesized and utilized as a formaldehyde-free water-repellent and flame-retardant for cotton fabrics. The flame retardancy of treated cotton fabrics was estimated by limiting oxygen index (LOI) test, vertical flammability test, and cone calorimetry test. The cotton fabrics treated with 350 g/L CPN-PDMS obtained excellent flame retardancy with an LOI value of 30.6% and the char length was only 4.3 cm. Combustion residues were studied using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analysis. Results show that CPN-PDMS can effectively enhance water repellency and fire resistance of cotton fabrics. Furthermore, the breaking strength test and the whiteness test strongly prove that the tensile strength and whiteness of the treated cotton fabrics were slightly lower than that of the pure cotton fabrics. The wash stability test showed that after 30 laundering cycles, the treated cotton fabrics still had an LOI value of 28.5% and a water-repellent effect of grade 80, indicating that CPN-PDMS was an excellent washing durability additive. In summary, these property enhancements of treated cotton fabrics were attributed to the synergistic effect of silicon-phosphorus-nitrogen elements in CPN-PDMS. Full article

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12 pages, 4081 KiB

Open AccessArticle

Water-Erodible Xanthan-Acrylate-Polyurethane Antifouling Coating

by Mohammad Mizanur Rahman, Md. Hasan Zahir, Mohammad Abu Jafar Mazumder and A. Madhan Kumar

Polymers 2019, 11(10), 1700; https://doi.org/10.3390/polym11101700 - 16 Oct 2019

Cited by 3 | Viewed by 3044

Abstract

Biopolymer xanthan (Xn) and its functionalized polymer xanthan acrylate (XnAc) were used to improve the antifouling properties of synthesized waterborne polyurethane (WBPU) coatings, namely, WBPU-Xn and WBPU-XnAc. XnAc was synthesized by functionalization of xanthan (Xn) using polyacrylic acid. Coating hydrophilicity, adhesive strength, and [...] Read more.

Biopolymer xanthan (Xn) and its functionalized polymer xanthan acrylate (XnAc) were used to improve the antifouling properties of synthesized waterborne polyurethane (WBPU) coatings, namely, WBPU-Xn and WBPU-XnAc. XnAc was synthesized by functionalization of xanthan (Xn) using polyacrylic acid. Coating hydrophilicity, adhesive strength, and erosion all varied with the Xn and XnAc contents. A moderate erosion rate was recorded only for the WBPU-XnAc coating. A good antifouling property for longer time was found in the WBPU-XnAc coating using zinc pyrithione as a biocide in the field test. Full article

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2018

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16 pages, 3962 KiB

Open AccessArticle

Cost-Effective, Highly Selective and Environmentally Friendly Superhydrophobic Absorbent from Cigarette Filters for Oil Spillage Clean up

by Qiancheng Xiong, Qiuhong Bai, Cong Li, Huan Lei, Chaoyun Liu, Yehua Shen and Hiroshi Uyama

Polymers 2018, 10(10), 1101; https://doi.org/10.3390/polym10101101 - 05 Oct 2018

Cited by 22 | Viewed by 4337

Abstract

Ecological and environmental damage caused by oil spillage has attracted great attention. Used cigarette filters (CF) have also caused negative environmental consequences. Converting CF to economical materials is a feasible way to address these problems. In this study, we demonstrate a simple method [...] Read more.

Ecological and environmental damage caused by oil spillage has attracted great attention. Used cigarette filters (CF) have also caused negative environmental consequences. Converting CF to economical materials is a feasible way to address these problems. In this study, we demonstrate a simple method for production of a highly hydrophobic absorbent from CF. CF was modified by using different volume ratios of octadecyltrichlorosilane and methyltrimethoxysilane. When the volume ratio was 3:2, the modified CF had the high water contact angle of 155°. It could selectively and completely absorb silicone oil from an oil-water mixture and showed a good absorption capacity of 38.3 g/g. The absorbed oil was readily and rapidly recovered by simple mechanical squeezing, and it could be reused immediately without any additional treatments. The as-obtained superhydrophobic modified CF retained an absorption capacity of 80% for pump oil and 82% for silicone oil after 10 cycles. The modified CF showed good elasticity in the test of repeated use. The present study provides novel design of a functional material for development of hydrophobic absorbents from used CF via a facile method toward oil spillage cleanup, as well as a new recycling method of CF to alleviate environmental impacts. Full article

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12 pages, 4021 KiB

Open AccessArticle

Hydrophobic Modification of Nanocellulose via a Two-Step Silanation Method

by Wensheng Lin, Xiaoyong Hu, Xueqing You, Yingying Sun, Yueqin Wen, Wenbin Yang, Xinxiang Zhang, Yan Li and Hanxian Chen

Polymers 2018, 10(9), 1035; https://doi.org/10.3390/polym10091035 - 18 Sep 2018

Cited by 24 | Viewed by 4894

Abstract

Dodecyltrimethoxysilane (DTMOS), which is a silanation modifier, was grafted onto nanocellulose crystals (NCC) through a two-step method using KH560 (ɤ-(2,3-epoxyproxy)propytrimethoxysilane) as a linker to improve the hydrophobicity of NCC. The reaction mechanism of NCC with KH560 and DTMOS and its surface [...] Read more.

Dodecyltrimethoxysilane (DTMOS), which is a silanation modifier, was grafted onto nanocellulose crystals (NCC) through a two-step method using KH560 (ɤ-(2,3-epoxyproxy)propytrimethoxysilane) as a linker to improve the hydrophobicity of NCC. The reaction mechanism of NCC with KH560 and DTMOS and its surface chemical characteristics were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and HCl–acetone titration. These analyses confirmed that KH560 was grafted onto the surface of NCC through the ring-opening reaction, before DTMOS was covalently grafted onto the surface of NCC using KH560 as a linker. The grafting of NCC with DTMOS resulted in an improvement in its hydrophobicity due to an increase in its water contact angle from 0° to about 140°. In addition, the modified NCC also possessed enhanced thermal stability. Full article

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11 pages, 4517 KiB

Open AccessArticle

Dentine Surface Morphology after Chlorhexidine Application—SEM Study

by Barbara Lapinska, Leszek Klimek, Jerzy Sokolowski and Monika Lukomska-Szymanska

Polymers 2018, 10(8), 905; https://doi.org/10.3390/polym10080905 - 11 Aug 2018

Cited by 19 | Viewed by 5045

Abstract

Chlorhexidine (CHX) is a widely known and a very popular antibacterial agent that decreases the level of cariogenic bacteria. CHX applied on the cavity surface of dentine may influence adhesive bond strength. The aim of the study was to evaluate the dentine surface [...] Read more.

Chlorhexidine (CHX) is a widely known and a very popular antibacterial agent that decreases the level of cariogenic bacteria. CHX applied on the cavity surface of dentine may influence adhesive bond strength. The aim of the study was to evaluate the dentine surface after different chlorhexidine digluconate (CHG) application protocols. Different CHG application protocols were introduced. A concentration of 0.2% or 2.0% CHG was applied on the etched or unetched dentine surface for 15 or 30 s, then water rinsed or drained. Scanning electron microscopy (SEM) observations and energy disperse spectrometer (EDS) analysis of the dentine surfaces were performed. The application of 0.2% CHG for 15 s, followed by draining, on either etched or unetched dentine surface effectively removed the smear layer, leaving the surface enriched with CHG deposits. Conclusions: The concentration of CHG and its application time influenced the amount of CHG deposits and the degree of smear layer removal from the dentine surface. Full article

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13 pages, 3613 KiB

Open AccessArticle

Enhancement of Heat Dissipation by Laser Micro Structuring for LED Module

by Libin Lu, Zhen Zhang, Yingchun Guan and Hongyu Zheng

Polymers 2018, 10(8), 886; https://doi.org/10.3390/polym10080886 - 08 Aug 2018

Cited by 10 | Viewed by 4074

Abstract

Optimization for heat dissipation plays a significant role in energy saving and high-efficiency utilizing of integrated electronics. In this paper, we present a study of micro structuring on polymer-based flexible substrate coupled with aluminum-alloy heat sink. The heat dissipation performance was investigated by [...] Read more.

Optimization for heat dissipation plays a significant role in energy saving and high-efficiency utilizing of integrated electronics. In this paper, we present a study of micro structuring on polymer-based flexible substrate coupled with aluminum-alloy heat sink. The heat dissipation performance was investigated by temperature evolution of a heat sink under natural convection by infrared (IR) camera, and results showed that the heat dissipation enhancement could be up to 25%. Moreover, the heat dissipation performance of a typical heat sink in terms of light-emitting diode (LED) hip was investigated via both thermal transient measurement and the finite element analysis (FEA). The maximum LED chip temperature of the laser-textured heat sink was approximately 22.4% lower than that of the as-received heat sink. We propose that these properties accompanied with the simplicity of fabrication make laser surface texturing a promising candidate for on-chip thermal management applications in electronics. Full article

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14 pages, 6225 KiB

Open AccessArticle

Layer-by-Layer Self-Assembly Strategy for Surface Modification of Aramid Fibers to Enhance Interfacial Adhesion to Epoxy Resin

by Zhaomin Li, Baihua Liu, Haijuan Kong, Muhuo Yu, Minglin Qin and Cuiqing Teng

Polymers 2018, 10(8), 820; https://doi.org/10.3390/polym10080820 - 25 Jul 2018

Cited by 23 | Viewed by 4281

Abstract

In this work, the layer-by-layer self-assembly technology was used to modify aramid fibers (AFs) to improve the interfacial adhesion to epoxy matrix. By virtue of the facile layer-by-layer self-assembly technique, poly(l-3,4-Dihydroxyphenylalanine) (l-PDOPA) was successfully coated on the surface of [...] Read more.

In this work, the layer-by-layer self-assembly technology was used to modify aramid fibers (AFs) to improve the interfacial adhesion to epoxy matrix. By virtue of the facile layer-by-layer self-assembly technique, poly(l-3,4-Dihydroxyphenylalanine) (l-PDOPA) was successfully coated on the surface of AFs, leading to the formation of AFs with controllable layers (nL-AF). Then, a hydroxyl functionalized silane coupling agent (KH550) was grafted on the surface of l-PDOPA coated AFs. The properties such as microstructure and surface morphology of AFs before and after modification were characterized by FTIR, XPS and FE-SEM. The results confirmed that l-PDOPA and KH550 were successfully introduced into the surface of AFs by electrostatic adsorption. The interfacial properties of AFs reinforced epoxy resin composites before and after coating were characterized by interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and FE-SEM, and the results show that the interfacial adhesion properties of the modified fiber/epoxy resin composites were greatly improved. Full article

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21 pages, 14705 KiB

Open AccessArticle

Comparative Adhesion, Ageing Resistance, and Surface Properties of Wood Plastic Composite Treated with Low Pressure Plasma and Atmospheric Pressure Plasma Jet

by Andrés Jesús Yáñez-Pacios and José Miguel Martín-Martínez

Polymers 2018, 10(6), 643; https://doi.org/10.3390/polym10060643 - 09 Jun 2018

Cited by 30 | Viewed by 4876

Abstract

Wood plastic composites (WPCs) have poor adhesion properties due to their high surface concentration in non-polar polymers. In this work, two different plasma surface treatments, low pressure plasma (LPP) and atmospheric pressure plasma jet (APPJ), are proposed to increase the surface energy and [...] Read more.

Wood plastic composites (WPCs) have poor adhesion properties due to their high surface concentration in non-polar polymers. In this work, two different plasma surface treatments, low pressure plasma (LPP) and atmospheric pressure plasma jet (APPJ), are proposed to increase the surface energy and adhesion property of WPC made with polyethylene (PE-WPC). After optimizing the conditions for each plasma surface treatment, the surface modifications and adhesion of PE-WPC treated with LPP and APPJ were compared. The optimal surface modifications of PE-WPC were obtained by treatment with Argon (Ar): Oxygen (O₂) LPP for 90 s, and with air APPJ by using a plasma nozzle-WPC surface distance of one centimeter and speed of platform of one meter per minute. Both plasma treatments produced similar chemical modifications and surface energies on the PE-WPC surface. The ablation was more important for Ar:O₂ LPP treatment, and the air APPJ treatment produced more extensive chemical modifications and more homogeneously removal of the wood component of the surface, rendering the polymer surface smoother. Adhesion of PE-WPC was similarly improved by treatment with both plasmas, from 56 N/m in the as-received to 92–102 N/m in the plasma treated PE-WPC joints. The influence of ageing at 24 °C and 40% relative humidity of the adhesive joints made with PE-WPC surface and treated with Ar:O₂ LPP and APPJ plasmas was studied. In the joints made with plasma-treated PE-WPC aged under open air for more than one day, the adhesion decreased. An adhesive strength near to that of the joint made with the as-received PE-WPC was obtained after six days. However, if the adhesive joint was created immediately after plasma treatment and peeled at different times, the adhesion was maintained and even increased, and the hydrophobic recovery of the plasma-treated PE-WPC surface was inhibited. Full article

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11 pages, 4448 KiB

Open AccessArticle

Promoting Barrier Performance and Cathodic Protection of Zinc-Rich Epoxy Primer via Single-Layer Graphene

by Jingrong Liu, Tao Liu, Zhangwei Guo, Na Guo, Yanhua Lei, Xueting Chang and Yansheng Yin

Polymers 2018, 10(6), 591; https://doi.org/10.3390/polym10060591 - 28 May 2018

Cited by 36 | Viewed by 5275

Abstract

The effect of single-layer graphene sheets (Gr) on the corrosion protection of zinc-rich epoxy primers (ZRPs) was investigated. Scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS) were used to characterize morphology and composition of the coatings after immersion for 25 days. [...] Read more.

The effect of single-layer graphene sheets (Gr) on the corrosion protection of zinc-rich epoxy primers (ZRPs) was investigated. Scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS) were used to characterize morphology and composition of the coatings after immersion for 25 days. The cross-sectional SEM images and X-ray photoelectron spectroscopy (XPS) confirmed that the addition of single-layer graphene facilitated assembling of zinc oxides on the interface between the coating and the steel. The open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) measurements revealed that both the cathodic protection and barrier performance of the ZRP were enhanced after addition of 0.6 wt. % Gr (Gr0.6-ZRP). In addition, the cathodic protection property of the Gr0.6-ZRP was characterized quantitatively by localized electrochemical impedance spectroscopy (LEIS) in the presence of an artificial scratch on the coating. The results demonstrate that moderate amounts of single-layer graphene can significantly improve corrosion resistance of ZRP, due to the barrier protection and cathodic protection effects. Full article

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17 pages, 7887 KiB

Open AccessArticle

Near-Infrared Light and Solar Light Activated Self-Healing Epoxy Coating having Enhanced Properties Using MXene Flakes as Multifunctional Fillers

by Yuting Zou, Liang Fang, Tianqi Chen, Menglong Sun, Chunhua Lu and Zhongzi Xu

Polymers 2018, 10(5), 474; https://doi.org/10.3390/polym10050474 - 26 Apr 2018

Cited by 61 | Viewed by 6171

Abstract

Two issues are required to be solved to bring intrinsically self-healing polymer coatings into real applications: remote activation and satisfied practical properties. Here, we used MXene, a newly reported two-dimensional material, to provide an epoxy coating with light-induced self-healing capabilities and we worked [...] Read more.

Two issues are required to be solved to bring intrinsically self-healing polymer coatings into real applications: remote activation and satisfied practical properties. Here, we used MXene, a newly reported two-dimensional material, to provide an epoxy coating with light-induced self-healing capabilities and we worked to enhance the properties of that coating. The self-healing coatings had a reversible crosslinking network based on the Diels-Alder reaction among maleimide groups from bis(4-maleimidopheny)methane and dangling furan groups in oligomers that were prepared through the condensation polymerization of diglycidylether of bisphenol A and furfurylamine. The results showed that the delaminated MXene flakes were small in size, around 900 nm, and dispersed well in self-healing coatings. The MXene flakes of only 2.80 wt % improved greatly the pencil hardness of the coating hardness from HB to 5H and the polarization resistance from 4.3 to 428.3 MΩ cm⁻². The self-healing behavior, however, was retarded by MXene flakes. Leveling agent acted a key part here to facilitate the gap closure driven by reverse plasticity to compensate for the limitation of macromolecular mobility resulting from the MXene flakes. The self-healing of coatings was achieved in 30 s by thermal treatment at 150 °C. The efficient self-healing was also demonstrated based on the recovery of the anti-corrosion capability. MXene flakes also played an evident photothermal role in generating heat via irradiation of near-infrared light at 808 nm and focused sunlight. The healing can be quickly obtained in 10 s under irradiation of near-infrared light at 808 nm having a power density of 6.28 W cm⁻² or in 10 min under irradiation of focused sunlight having a power density of 4.0 W cm⁻². Full article

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13 pages, 2635 KiB

Open AccessArticle

Multienzyme Immobilized Polymeric Membrane Reactor for the Transformation of a Lignin Model Compound

by Rupam Sarma, Md. Saiful Islam, Mark P. Running and Dibakar Bhattacharyya

Polymers 2018, 10(4), 463; https://doi.org/10.3390/polym10040463 - 23 Apr 2018

Cited by 17 | Viewed by 5248

Abstract

We have developed an integrated, multienzyme functionalized membrane reactor for bioconversion of a lignin model compound involving enzymatic catalysis. The membrane bioreactors were fabricated through the layer-by-layer assembly approach to immobilize three different enzymes (glucose oxidase, peroxidase and laccase) into pH-responsive membranes. This [...] Read more.

We have developed an integrated, multienzyme functionalized membrane reactor for bioconversion of a lignin model compound involving enzymatic catalysis. The membrane bioreactors were fabricated through the layer-by-layer assembly approach to immobilize three different enzymes (glucose oxidase, peroxidase and laccase) into pH-responsive membranes. This novel membrane reactor couples the in situ generation of hydrogen peroxide (by glucose oxidase) to oxidative conversion of a lignin model compound, guaiacylglycerol-β-guaiacyl ether (GGE). Preliminary investigation of the efficacy of these functional membranes towards GGE degradation is demonstrated under convective flow mode. Over 90% of the initial feed could be degraded with the multienzyme immobilized membranes at a residence time of approximately 22 s. GGE conversion product analysis revealed the formation of oligomeric oxidation products upon reaction with peroxidase, which may be a potential hazard to membrane bioreactors. These oxidation products could further be degraded by laccase enzymes in the multienzymatic membranes, explaining the potential of multi enzyme membrane reactors. The multienzyme incorporated membrane reactors were active for more than 30 days of storage time at 4 °C. During this time span, repetitive use of the membrane reactor was demonstrated involving 5–6 h of operation time for each cycle. The membrane reactor displayed encouraging performance, losing only 12% of its initial activity after multiple cycles of operation. Full article

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12 pages, 19136 KiB

Open AccessArticle

An Environmentally Friendly Approach for the Fabrication of Conductive Superhydrophobic Coatings with Sandwich-Like Structures

by Xiaomin Luo, Wenjie Hu, Min Cao, Huijun Ren, Jianyan Feng and Mengyuan Wei

Polymers 2018, 10(4), 378; https://doi.org/10.3390/polym10040378 - 30 Mar 2018

Cited by 9 | Viewed by 4649

Abstract

A large amount of research has been devoted to developing novel superhydrophobic coatings. However, it is still a great challenge to pursuean environmentally friendly method that leads to superhydrophobic coatings. Herein, we demonstrate for the first time, an environmentally friendly method for the [...] Read more.

A large amount of research has been devoted to developing novel superhydrophobic coatings. However, it is still a great challenge to pursuean environmentally friendly method that leads to superhydrophobic coatings. Herein, we demonstrate for the first time, an environmentally friendly method for the preparation of conductive superhydrophobic coatings with sandwich-like structures by using aminoethylaminopropyl polydimethylsiloxane modified waterborne polyurethane (SiWPU) and N-octadecylamine functionalized multi-wall carbon nanotubes. These environmentally friendly coatings with the sheet resistance of 1.1 ± 0.1 kΩ/sq exhibit a high apparent contact angle of 158.1° ± 2° and a low sliding angle below 1°. The influence of the surface texture before and after heat treatment on the wetting properties is discussed. In addition, the coatings can be electrically heated by 3~113 °C with a voltage of 12~72 V, and thus, can be used for deicing. Furthermore, the resulting coatings demonstrate good performance of wear resistance and ultraviolet resistance, which will have broad application potential in harsh environments. Full article

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16 pages, 11777 KiB

Open AccessArticle

Novel Dual-Component Microencapsulated Hydrophobic Amine and Microencapsulated Isocyanate Used for Self-Healing Anti-Corrosion Coating

by Maolian Guo, Wei Li, Na Han, Jianping Wang, Junfeng Su, Jianjie Li and Xingxiang Zhang

Polymers 2018, 10(3), 319; https://doi.org/10.3390/polym10030319 - 14 Mar 2018

Cited by 39 | Viewed by 5897

Abstract

Dual component microencapsulated hydrophobic amine and microencapsulated isocyanate were designed and fabricated for self-healing anti-corrosion coating. In this system, novel hydrophobic polyaspartic acid ester (PAE) and isophorone diisocyanate (IPDI) were microencapsulated respectively with melamine-formaldehyde (MF) as shell via in situ polymerization. To reduce [...] Read more.

Dual component microencapsulated hydrophobic amine and microencapsulated isocyanate were designed and fabricated for self-healing anti-corrosion coating. In this system, novel hydrophobic polyaspartic acid ester (PAE) and isophorone diisocyanate (IPDI) were microencapsulated respectively with melamine-formaldehyde (MF) as shell via in situ polymerization. To reduce the reaction activity between shell-forming MF prepolymer and PAE, another self-healing agent tung oil (TO) was dissolved in PAE and subsequently employed as core material. With field-emission scanning electron microscopy (FE-SEM) and optical microscopy (OM), the resultant microencapsulated IPDI with diameter of 2–5 μm showed a spherical shape and smooth surface. More importantly, both the morphology and microstructure of microencapsulated PAE enhanced significantly after addition of TO. Fourier transform infrared spectra (FTIR) analysis confirmed the molecular structure of chemical structure of the microcapsules. Thermal gravimetric analysis (TGA) indicated that both kinds of microcapsules exhibit excellent thermal resistance with the protection of MF shell. Furthermore, the self-healing epoxy coating system containing microencapsulated IPDI and microencapsulated PAE/TO was prepared and investigated. From the micrographs of true color confocal microscope (TCCM), the self-healing coating containing dual-component microcapsules showed excellent self-repairing performance compared to single microencapsulated IPDI system, and the optimal content of dual-component microcapsules in epoxy coating was 20 wt % approximately. Full article

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2017

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6700 KiB

Open AccessArticle

Immobilization of Platelet-Rich Plasma onto COOH Plasma-Coated PCL Nanofibers Boost Viability and Proliferation of Human Mesenchymal Stem Cells

by Anastasiya Solovieva, Svetlana Miroshnichenko, Andrey Kovalskii, Elizaveta Permyakova, Zakhar Popov, Eva Dvořáková, Philip Kiryukhantsev-Korneev, Aleksei Obrosov, Josef Polčak, Lenka Zajíčková, Dmitry V. Shtansky and Anton Manakhov

Polymers 2017, 9(12), 736; https://doi.org/10.3390/polym9120736 - 20 Dec 2017

Cited by 35 | Viewed by 7657

Abstract

The scaffolds made of polycaprolactone (PCL) are actively employed in different areas of biology and medicine, especially in tissue engineering. However, the usage of unmodified PCL is significantly restricted by the hydrophobicity of its surface, due to the fact that its inert surface [...] Read more.

The scaffolds made of polycaprolactone (PCL) are actively employed in different areas of biology and medicine, especially in tissue engineering. However, the usage of unmodified PCL is significantly restricted by the hydrophobicity of its surface, due to the fact that its inert surface hinders the adhesion of cells and the cell interactions on PCL surface. In this work, the surface of PCL nanofibers is modified by Ar/CO₂/C₂H₄ plasma depositing active COOH groups in the amount of 0.57 at % that were later used for the immobilization of platelet-rich plasma (PRP). The modification of PCL nanofibers significantly enhances the viability and proliferation (by hundred times) of human mesenchymal stem cells, and decreases apoptotic cell death to a normal level. According to X-ray photoelectron spectroscopy (XPS), after immobilization of PRP, up to 10.7 at % of nitrogen was incorporated into the nanofibers surface confirming the grafting of proteins. Active proliferation and sustaining the cell viability on nanofibers with immobilized PRP led to an average number of cells of 258 ± 12.9 and 364 ± 34.5 for nanofibers with ionic and covalent bonding of PRP, respectively. Hence, our new method for the modification of PCL nanofibers with PRP opens new possibilities for its application in tissue engineering. Full article

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5403 KiB

Open AccessArticle

The Effects of Using Sodium Alginate Hydrosols Treated with Direct Electric Current as Coatings for Sausages

by Żaneta Król, Dominika Kulig, Krzysztof Marycz, Anna Zimoch-Korzycka and Andrzej Jarmoluk

Polymers 2017, 9(11), 602; https://doi.org/10.3390/polym9110602 - 11 Nov 2017

Cited by 6 | Viewed by 4165

Abstract

We investigated the effect of sodium alginate hydrosols (1%) with 0.2% of NaCl treated with direct electric current (DC) used as a coating on microbial (Total Viable Counts, Psychrotrophic bacteria, yeast and molds, Lactic acid bacteria, Enterobacteriaceae), physiochemical (pH, lipid oxidation, antioxidant [...] Read more.

We investigated the effect of sodium alginate hydrosols (1%) with 0.2% of NaCl treated with direct electric current (DC) used as a coating on microbial (Total Viable Counts, Psychrotrophic bacteria, yeast and molds, Lactic acid bacteria, Enterobacteriaceae), physiochemical (pH, lipid oxidation, antioxidant activity, weight loss, color) and sensory properties of skinned pork sausages or with artificial casing stored at 4 °C for 28 days. Moreover, the cytotoxicity analysis of sodium alginate hydrogels was performed. The results have shown that application of experimental coatings on the sausage surface resulted in reducing all tested groups of microorganisms compared to control after a 4-week storage. The cytotoxicity analysis revealed that proliferation of RAW 264.7 and L929 is not inhibited by the samples treated with 200 mA. Ferric reducing antioxidant power (FRAP) and free radical scavenging activity (DPPH) analyses showed that there are no significant differences in antioxidant properties between control samples and those covered with sodium alginate. After 28 days of storage, the highest value of thiobarbituric acid-reactive substances (TBARS) was noticed for variants treated with 400 mA (1.07 mg malondialdehyde/kg), while it was only slightly lower for the control sample (0.95 mg MDA/kg). The obtained results suggest that sodium alginate treated with DC may be used as a coating for food preservation because of its antimicrobial activity and lack of undesirable impact on the quality factors of sausages. Full article

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4126 KiB

Open AccessArticle

Surface Modification of Cardiovascular Stent Material 316L SS with Estradiol-Loaded Poly (trimethylene carbonate) Film for Better Biocompatibility

by Hang Yao, Jingan Li, Na Li, Kebing Wang, Xin Li and Jin Wang

Polymers 2017, 9(11), 598; https://doi.org/10.3390/polym9110598 - 10 Nov 2017

Cited by 34 | Viewed by 4251

Abstract

A delay in the endothelialization process represents a bottleneck in the application of a drug-eluting stent (DES) during cardiovascular interventional therapy, which may lead to a high risk of late restenosis. In this study, we used a novel active drug, estradiol, which may [...] Read more.

A delay in the endothelialization process represents a bottleneck in the application of a drug-eluting stent (DES) during cardiovascular interventional therapy, which may lead to a high risk of late restenosis. In this study, we used a novel active drug, estradiol, which may contribute to surface endothelialization of a DES, and prepared an estradiol-loaded poly (trimethylene carbonate) film (PTMC-E5) on the surface of the DES material, 316L stainless steel (316L SS), in order to evaluate its function in improving surface endothelialization. All the in vitro and in vivo experiments indicated that the PTMC-E5 film significantly improved surface hemocompatibility and anti-hyperplasia, anti-inflammation and pro-endothelialization properties. This novel drug-delivery system may provide a breakthrough for the surface endothelialization of cardiovascular DES. Full article

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1921 KiB

Open AccessArticle

Surface and Protein Adsorption Properties of 316L Stainless Steel Modified with Polycaprolactone Film

by Shih-Hang Chang and Yuan-Chien Hsiao

Polymers 2017, 9(10), 545; https://doi.org/10.3390/polym9100545 - 23 Oct 2017

Cited by 15 | Viewed by 4806

Abstract

The surface and protein adsorption properties of 316L stainless steel (316L SS) modified with polycaprolactone (PCL) films are systematically investigated. The wettability of the PCL films was comparable to that of bare 316L SS because the rough surface morphology of the PCL films [...] Read more.

The surface and protein adsorption properties of 316L stainless steel (316L SS) modified with polycaprolactone (PCL) films are systematically investigated. The wettability of the PCL films was comparable to that of bare 316L SS because the rough surface morphology of the PCL films counteracts their hydrophobicity. Surface modification with PCL film significantly improves the corrosion resistance of the 316L SS because PCL is insulating in nature. A coating of PCL film effectively reduces the amount of adhered bovine serum albumin (BSA) on the surface of 316L SS in a bicinchoninic acid protein assay. PCL is both biodegradable and biocompatible, suggesting the potential for the surface modification of implants used in human bodies; in these applications, excellent corrosion resistance and anticoagulant properties are necessary. Full article

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