Polymers

16 pages, 4676 KiB

Open AccessArticle

Colloidal Stability of CA, SDS and PVA Coated Iron Oxide Nanoparticles (IONPs): Effect of Molar Ratio and Salinity

by Siti Nurliyana Che Mohamed Hussein, Zulhelmi Amir, Badrul Mohamed Jan, Munawar Khalil and Azlinda Azizi

Polymers 2022, 14(21), 4787; https://doi.org/10.3390/polym14214787 - 07 Nov 2022

Cited by 6 | Viewed by 2076

Abstract

Iron Oxide Nanoparticles (IONPs) have received unprecedented interest in various applications. The main challenges in IONPs are fluid stability due to agglomeration in a saline condition. This paper aims to investigate the colloidal stability of citric acid (CA), sodium dodecyl sulphate (SDS) and [...] Read more.

Iron Oxide Nanoparticles (IONPs) have received unprecedented interest in various applications. The main challenges in IONPs are fluid stability due to agglomeration in a saline condition. This paper aims to investigate the colloidal stability of citric acid (CA), sodium dodecyl sulphate (SDS) and polyvinyl alcohol (PVA) under various molar ratios and levels of salinity. Firstly, the IONPs were synthesized using a facile co-precipitation approach. Secondly, the IONPs were coated using a simple dip-coating method by varying the molar ratio of CA, SDS and PVA. Next, the coated IONPs were characterized by using an X-ray Diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and a Field Emission Scanning Electron Microscope (FESEM) for the morphological and crystallographic study of coated IONPs. Finally, the coated IONPs were characterized for their zeta potential value and hydrodynamic size using a Zetasizer and their turbidity was measured using a turbidity meter. It was found that at a low salinity level, 0.07 M of CA-IONPs, a high zeta potential value, a smaller hydrodynamic size, and a high turbidity value of −40.9 mV, 192 nm and 159 NTU were observed, respectively. At a high salinity level, 1.0 M SDS-IONPs recorded a high zeta potential value of 23.63 mV, which corresponds to a smaller hydrodynamic size (3955 nm) and high turbidity result (639 NTU). These findings are beneficial for delivering cutting-edge knowledge, especially in enhanced oil recovery (EOR) applications. Full article

(This article belongs to the Special Issue Patterns or Interfaces in Polymers and Polymeric Nanocomposites for Applications)

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20 pages, 11950 KiB

Open AccessReview

Rare Earth Elements Uptake by Synthetic Polymeric and Cellulose-Based Materials: A Review

by Gabriel Salfate and Julio Sánchez

Polymers 2022, 14(21), 4786; https://doi.org/10.3390/polym14214786 - 07 Nov 2022

Cited by 7 | Viewed by 2284

Abstract

Contemporary industrial processes and the application of new technologies have increased the demand for rare earth elements (REEs). REEs are critical components for many applications related to semiconductors, luminescent molecules, catalysts, batteries, and so forth. REEs refer to a group of 17 elements [...] Read more.

Contemporary industrial processes and the application of new technologies have increased the demand for rare earth elements (REEs). REEs are critical components for many applications related to semiconductors, luminescent molecules, catalysts, batteries, and so forth. REEs refer to a group of 17 elements that have similar chemical properties. REE mining has increased considerably in the last decade and is starting an REE supply crisis. Recently, the viability of secondary REE sources, such as mining wastewaters and acid mine drainage (AMD), has been considered. A strategy to recover REEs from secondary water-related sources is through the usage of adsorbents and ion exchange materials in preconcentration steps due to their presence in low concentrations. In the search for more sustainable processes, the evaluation of synthetic polymers and natural source materials, such as cellulose-based materials, for REE capture from secondary sources should be considered. In this review, the chemistry, sources, extraction, uses, and environmental impact of REEs are briefly described to finally focus on the study of different adsorption/ion exchange materials and their performance in capturing REEs from water sources, moving from commercially available ion exchange resins to cellulose-based materials. Full article

(This article belongs to the Special Issue Cellulose Nanocrystals and Cellulose-Based Materials: Synthesis, Characterization and Application)

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17 pages, 1777 KiB

Open AccessArticle

A Novel Multi-Region, Multi-Phase, Multi-Component-Mixture Modeling Approach to Predicting the Thermodynamic Behaviour of Thermoplastic Composites during the Consolidation Process

by Eva Kobler, Janos Birtha, Christian Marschik, Klaus Straka, Georg Steinbichler, Paul Zwicklhuber and Sven Schlecht

Polymers 2022, 14(21), 4785; https://doi.org/10.3390/polym14214785 - 07 Nov 2022

Cited by 2 | Viewed by 1470

Abstract

In the processing of thermoplastic composites, great importance is attributed to the consolidation step, as it can significantly reduce the porosity of the semi-finished product and thus influence considerably the quality of the final component. This work presents an approach to modeling the [...] Read more.

In the processing of thermoplastic composites, great importance is attributed to the consolidation step, as it can significantly reduce the porosity of the semi-finished product and thus influence considerably the quality of the final component. This work presents an approach to modeling the thermodynamic behavior of composite materials during hot-press consolidation. For this purpose a multi-region, multi-phase and multi-component-mixture model was developed using the simulation toolbox OpenFOAM^®. The sensitivity of the model was tested by varying the thermal parameters and mesh resolution, confirming its robustness. Validity of the model was confirmed by comparing simulation results to experimental data for (i) polycarbonate with 44% carbon fiber by volume and (ii) polypropylene with 45.3% glass fiber by volume. The simulation allows very precise estimation of when a particular temperature, such as the glass transition temperature or melting point, will be reached at the core of a composite. In relation to the total process time, maximum deviation of the simulation from the experimental data amounted to 2.84%. Therefore, the model is well suited for process optimization, it offers a basis for further model implementations and the creation of a digital twin. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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20 pages, 6072 KiB

Open AccessArticle

Poly (Vinyl Alcohol)/Agar Hydrogel Electrolytes Based Flexible All-in-One Supercapacitors with Conducting Polyaniline/Polypyrrole Electrodes

by Khadija Hasan, Shahid Bashir, Ramesh Subramaniam, Ramesh Kasi, Kashif Kamran, Javed Iqbal, Hamed Algarni, Abdullah G. Al-Sehemi, S. Wageh, M. Pershaanaa and Fathiah Kamarulazam

Polymers 2022, 14(21), 4784; https://doi.org/10.3390/polym14214784 - 07 Nov 2022

Cited by 4 | Viewed by 2259

Abstract

The major components of supercapacitor are electrodes and electrolytes which are fabricated using various materials and methods. Hydrogel is one such material that is used in supercapacitors as electrodes and electrolytes or both. Hydrogels are usually described as a soft and porous network [...] Read more.

The major components of supercapacitor are electrodes and electrolytes which are fabricated using various materials and methods. Hydrogel is one such material that is used in supercapacitors as electrodes and electrolytes or both. Hydrogels are usually described as a soft and porous network of polymer materials that can swell in water because of the hydrophilic nature of its polymer chains, compriseng a 3D structure. It is well known that supercapacitors possess high-power density but low energy density. For enhancing energy density of these electrochemical cells and a boost in its electrochemical performance and specific capacity, binder free conducting polymer hydrogel electrodes have gained immense attention, especially polyaniline (PANI) and polypyrrole (PPy). Therefore, in this work, chemically crosslinked PVA/Agar hydrogel electrolytes have been prepared and employed. Agar has been added in PVA since it is environmentally friendly, biodegradable, and cost-effective natural polymer. Subsequently, the binder free polyaniline/polypyrrole electrodes were grown on the PVA/Agar hydrogel electrolytes to fabricate all-in-one flexible hydrogels. The synthesized hydrogels were characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) analysis, Field emission scanning electron microscope (FESEM) and mechanical studies. Then, the all-in-one flexible supercapacitors were fabricated using the hydrogels. The electrochemical studies such cyclic voltammetry (CV), galvanic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS) studies. The fabricated all-in-one lamination free supercapacitors showed promising results and by comparing all four samples, PAP2 where 5 mL of PVA was used in combination with 3 mL of Agar and 5 mL of PANI and PPy each, exhibited the highest areal capacitance of 750.13 mF/cm², energy density of 103.02 μWh/cm², and 497.22 μW/cm² power density. The cyclic stability study revealed the 149% capacity retention after 15,000 cycles. Full article

(This article belongs to the Special Issue Recent Progress on Polymer Electrolytes for Solar Cells and Supercapacitors)

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19 pages, 5795 KiB

Open AccessArticle

Comparative Mechanical Study of Pressure Sensitive Adhesives over Aluminium Substrates for Industrial Applications

by Marta Ortega-Iguña, Mariane Chludzinski and José María Sánchez-Amaya

Polymers 2022, 14(21), 4783; https://doi.org/10.3390/polym14214783 - 07 Nov 2022

Cited by 5 | Viewed by 2099

Abstract

The use of adhesives for fixing low-weight elements is showing increasing interest in the industry, as it would reduce the weight of the assembly, costs, and production time. Specifically, the application of pressure-sensitive adhesives (PSAs) to join non-structural naval components to aluminium substrates [...] Read more.

The use of adhesives for fixing low-weight elements is showing increasing interest in the industry, as it would reduce the weight of the assembly, costs, and production time. Specifically, the application of pressure-sensitive adhesives (PSAs) to join non-structural naval components to aluminium substrates has not yet been reported. In the present work, a study of the mechanical behaviour of different double-sided PSAs applied on bare aluminium alloy substrates is performed. The influence of surface roughness, surface chemical treatments, and the matrix of the adhesives is studied through different mechanical tests, such as shear, T-peel, and creep. The application of an adhesion promoter improved the mechanical behaviour. Low roughness substrates provided better performance than ground samples. Acrylic foam adhesives were subjected to creep tests, whose results were fitted to a simple mathematical model, predicting the fracture time as a function of the applied load. Full article

(This article belongs to the Special Issue Mechanical and Adhesive Properties of Polymeric Materials)

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28 pages, 14110 KiB

Open AccessReview

Anti-Corrosion Reinforcements Using Coating Technologies—A Review

by Lei Yan, Wenjie Deng, Neng Wang, Xuanyi Xue, Jianmin Hua and Zengshun Chen

Polymers 2022, 14(21), 4782; https://doi.org/10.3390/polym14214782 - 07 Nov 2022

Cited by 3 | Viewed by 2735

Abstract

Coated reinforcements are expected to improve the performance of reinforced concrete in aggressive environments, but different kinds of coated reinforcements can express a variety of properties, which can confuse researchers and engineers. This paper reviews the manufacture, corrosion mechanisms, behaviors, and applications of [...] Read more.

Coated reinforcements are expected to improve the performance of reinforced concrete in aggressive environments, but different kinds of coated reinforcements can express a variety of properties, which can confuse researchers and engineers. This paper reviews the manufacture, corrosion mechanisms, behaviors, and applications of popular or promising coated reinforcements, incorporating galvanized reinforcements (GRs), epoxy coated reinforcements (ECRs), stainless cladding reinforcements (SCRs), and steel-fiber reinforced polymer composite bars (SFCBs). In terms of manufacture, GRs and ECRs should focus on minimizing the negative effect of manufacture on performance, while SCRs and SFCBs should reduce the cost and increase the production capacity. Behaviors of GRs and ECRs are primarily determined by the steel substrate, but the behaviors of SCRs and SFCBs are primarily affected by the coat and core, and their interaction. The corrosion mechanism of GRs and SCRs is about oxidation, while that of SFCBs is about hydrolysis. ECRs are usually corroded under film, which can be a cause of premature failure. Corrosion embrittles SCRs, as well as bare bars, but corrosion of SFCBs usually causes a reduction in maximum strength. The investigation of the corrosion behaviors of GRs and ECRs focuses on bond strength. GRs have controversial performance. ECRs have been proven to have drawbacks regarding bond strength. The use of anti-corrosion reinforcement is uneven in regions, which may correlate with the development of technology and the economy. Full article

(This article belongs to the Special Issue Advances in Fiber-Reinforced Polymer Concrete)

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16 pages, 6133 KiB

Open AccessArticle

Grating Assembly Dissected in Periodic Bands of Poly (Butylene Adipate) Modulated with Poly (Ethylene Oxide)

by Chia-I. Chang, Eamor M. Woo and Selvaraj Nagarajan

Polymers 2022, 14(21), 4781; https://doi.org/10.3390/polym14214781 - 07 Nov 2022

Cited by 1 | Viewed by 1455

Abstract

Polarized optical microscopy (POM), scanning electron microscopy (SEM), and synchrotron microbeam wide-angle X-ray diffraction (WAXD) were used to investigate the mechanisms of periodic assemblies leading to ring-banded crystal aggregates with light-grating capacity for iridescence in poly (1,4-butylene adipate) (PBA) modulated with poly (ethylene [...] Read more.

Polarized optical microscopy (POM), scanning electron microscopy (SEM), and synchrotron microbeam wide-angle X-ray diffraction (WAXD) were used to investigate the mechanisms of periodic assemblies leading to ring-banded crystal aggregates with light-grating capacity for iridescence in poly (1,4-butylene adipate) (PBA) modulated with poly (ethylene oxide) (PEO). A critical finding is that the PBA crystal assembly on the top surface and in the interior constitutes a grating architecture, with a cross-bar pitch equaling the inter-band spacing. The inner lamellae are arranged perpendicularly to the substrate under the ridge region, where they scroll, bend, and twist 90° to branch out newly spawned lamellae to form the parallel lamellae under the valley region. The cross-hatch grating with a fixed inter-spacing in the PBA aggregated crystals is proved in this work to perfectly act as light-interference entities capable of performing iridescence functions, which can be compared to those widely seen in many of nature’s organic bio-species or inorganic minerals such as opals. This is a novel breakthrough finding for PBA or similar polymers, such as photonic crystals, especially when the crystalline morphology could be custom-made and modulated with a second constituent. Full article

(This article belongs to the Special Issue Polymer Based Electronic Devices and Sensors)

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19 pages, 6632 KiB

Open AccessArticle

Low Impact Velocity Modeling of 3D Printed Spatially Graded Elastomeric Lattices

by Jose Angel Diosdado-De la Peña, Charles M. Dwyer, David Krzeminski, Eric MacDonald, Alberto Saldaña-Robles, Pedro Cortes and Kyosung Choo

Polymers 2022, 14(21), 4780; https://doi.org/10.3390/polym14214780 - 07 Nov 2022

Cited by 3 | Viewed by 2034

Abstract

Additive manufacturing technologies have facilitated the construction of intricate geometries, which otherwise would be an extenuating task to accomplish by using traditional processes. Particularly, this work addresses the manufacturing, testing, and modeling of thermoplastic polyurethane (TPU) lattices. Here, a discussion of different unit [...] Read more.

Additive manufacturing technologies have facilitated the construction of intricate geometries, which otherwise would be an extenuating task to accomplish by using traditional processes. Particularly, this work addresses the manufacturing, testing, and modeling of thermoplastic polyurethane (TPU) lattices. Here, a discussion of different unit cells found in the literature is presented, along with the based materials used by other authors and the tests performed in diverse studies, from which a necessity to improve the dynamic modeling of polymeric lattices was identified. This research focused on the experimental and numerical analysis of elastomeric lattices under quasi-static and dynamic compressive loads, using a Kelvin unit cell to design and build non-graded and spatially side-graded lattices. The base material behavior was fitted to an Ogden 3rd-order hyperelastic material model and used as input for the numerical work through finite element analysis (FEA). The quasi-static and impact loading FEA results from the lattices showed a good agreement with the experimental data, and by using the validated simulation methodology, additional special cases were simulated and compared. Finally, the information extracted from FEA allowed for a comparison of the performance of the lattice configurations considered herein. Full article

(This article belongs to the Special Issue Structure and Properties of Polymeric Materials in Additive Manufacturing)

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15 pages, 2178 KiB

Open AccessArticle

Removal Efficiency of Sulfapyridine from Contaminated Surface Water by Carboxylated Graphene Oxide Blended PVDF Composite Ultrafiltration Membrane with Activated Carbon

by Yuliang Chen, Libo Ba, Yini He and Xuesong Yi

Polymers 2022, 14(21), 4779; https://doi.org/10.3390/polym14214779 - 07 Nov 2022

Cited by 1 | Viewed by 1078

Abstract

In this study, sulfapyridine (SPY), an antibiotic that is less commonly treated by membrane filtration techniques but is frequently detected in the aqueous environment and at higher concentrations than other detected antibiotics, was selected for investigation. A composite ultrafiltration membrane for the removal [...] Read more.

In this study, sulfapyridine (SPY), an antibiotic that is less commonly treated by membrane filtration techniques but is frequently detected in the aqueous environment and at higher concentrations than other detected antibiotics, was selected for investigation. A composite ultrafiltration membrane for the removal of sulfapyridine (SPY) antibiotics from water was fabricated using polyvinylidene fluoride (PVDF), polyvinylpyrrolidone (PVP), and carboxyl-functionalized graphene oxide (CFGO) as additives. The changes in retention rate and pure water flux of sulfapyridine by the composite ultrafiltration membrane were investigated by changing the ratios of the prepared ultrafiltration membrane materials under the conditions of low-pressure operation to explore the optimal experimental conditions. The results showed that the addition of PVP and CFGO significantly increased the number of membrane pores and their pore size. The addition of CFGO in the membrane significantly improved the hydrophilicity of the membrane. The contact angle decreased from 83.7 to 31.6°. Compared to ordinary PVDF ultrafiltration membranes, the membrane’s pure water flux increased nearly three times to 2612.95 L/(m²·h). The removal rate of SPY was 56.26% under the optimal conditions. When the composite ultrafiltration membrane was combined with activated carbon, the removal rate of SPY was 92.67%, which was nine times higher than that of activated carbon alone. At this time, the flux of the composite membrane was 2610.23 L/(m²·h). This study proposes a simple, efficient, and low production cost solution for the removal of sulfapyridine from water. Full article

(This article belongs to the Collection Polymer Materials for Adsorption Applications)

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17 pages, 41472 KiB

Open AccessArticle

Ligustrazine as an Extract from Medicinal and Edible Plant Chuanxiong Encapsulated in Liposome–Hydrogel Exerting Antioxidant Effect on Preventing Skin Photoaging

by Chang Liu, Ying Xia, Yufan Li, Yongfeng Cheng, Hongmei Xia, Yu Wang, Yan Yue, Yifang Wu, Xiaoman Cheng, Yinxiang Xu and Zili Xie

Polymers 2022, 14(21), 4778; https://doi.org/10.3390/polym14214778 - 07 Nov 2022

Cited by 9 | Viewed by 1813

Abstract

Long-term sunlight exposure will cause the accumulation of free radicals in the skin and lead to oxidative damage and aging, antioxidant drugs have gradually become the focus of research, but there is little research on antioxidant drugs for percutaneous treatment. The purpose of [...] Read more.

Long-term sunlight exposure will cause the accumulation of free radicals in the skin and lead to oxidative damage and aging, antioxidant drugs have gradually become the focus of research, but there is little research on antioxidant drugs for percutaneous treatment. The purpose of this study was to prepare ligustrazine hydrochloride (TMPZ)-loaded liposome–hydrogel (TMPZ-LG), evaluate its antioxidant properties, and apply it on the skin of mice to observe whether it had preventive and therapeutic effect on the irradiation under the ultraviolet rays, in an attempt to make it into a new kind of delivery through the skin. TMPZ-LG was prepared by the combination of film dispersion and sodium carboxymethylcellulose (2%, CMC-Na) natural swelling method. The release rates in vitro permeation across the dialysis membrane and ex vivo transdermal had both reached 40%; the scavenging effect of TMPZ-LG on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and H₂O₂ were 65.57 ± 4.13% and 73.06 ± 5.65%; the inhibition rate of TMPZ-LG on malondialdehyde (MDA) production in liver homogenate and anti-low density lipoprotein (LDL) oxidation experiments ex vivo were 15.03 ± 0.9% and 21.57 ± 1.2%. Compared with untreated mice, the skin pathological symptoms of mice coated with TMPZ-LG were significantly reduced after ultraviolet irradiation, and there was statistical significance. The results showed TMPZ-LG could exert good antioxidant activity in vitro and ex vivo; therefore, it is feasible to prevent and treat skin oxidation. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Pharmaceutical Applications III)

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15 pages, 6173 KiB

Open AccessArticle

Influence of Mixing Order on the Synthesis of Geopolymer Concrete

by Timur Mukhametkaliyev, Md. Hazrat Ali, Viktor Kutugin, Olesya Savinova and Vladimir Vereschagin

Polymers 2022, 14(21), 4777; https://doi.org/10.3390/polym14214777 - 07 Nov 2022

Cited by 5 | Viewed by 2593

Abstract

Geopolymers are high-performance, cost-effective materials made from industrial waste that ideally fit the needs of 3D printing technology used in construction. The novelty of the present work lies in the investigation of methods to mix geopolymer concrete from fly ash (FA) class F, [...] Read more.

Geopolymers are high-performance, cost-effective materials made from industrial waste that ideally fit the needs of 3D printing technology used in construction. The novelty of the present work lies in the investigation of methods to mix geopolymer concrete from fly ash (FA) class F, ground granulated blast furnace slag (GGBS), and raw calcined kaolin clay (RCKC) to determine the mixing procedure which provides the best mechanical strength and structural integrity. The experimental results show that aluminosilicates with different reaction parameters when mixed one after another provide the optimal results while the geopolymer concrete possesses the highest compressive strength and the denser structure. The results demonstrated that the reactivity of GGBS, FA, and RCKC increased for different depolymerization speeds of the selected aluminosilicates. This research will provide results on how to improve the mixing order for geopolymer synthesis for 3D printing demands. The highest compressive strength and denser structure of geopolymer concrete is achieved when each type of aluminosilicate is mixed with an alkaline medium separately. Full article

(This article belongs to the Special Issue Progress in 3D Printing)

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13 pages, 3394 KiB

Open AccessArticle

A Novel Dual-Ion Capacitive Deionization System Design with Ultrahigh Desalination Performance

by Yuxin Jiang, Zhiguo Hou, Lvji Yan, Haiyin Gang, Haiying Wang and Liyuan Chai

Polymers 2022, 14(21), 4776; https://doi.org/10.3390/polym14214776 - 07 Nov 2022

Cited by 1 | Viewed by 1596

Abstract

Capacitive deionization is an emerging desalination technology with mild operation conditions and high energy efficiency. However, its application is limited due to the low deionization capacity of traditional capacitive electrodes. Herein, we report a novel dual-ion capacitive deionization system with a lithium-ion battery [...] Read more.

Capacitive deionization is an emerging desalination technology with mild operation conditions and high energy efficiency. However, its application is limited due to the low deionization capacity of traditional capacitive electrodes. Herein, we report a novel dual-ion capacitive deionization system with a lithium-ion battery cathode LiMn₂O₄/C and a sodium-ion battery anode NaTi₂(PO₄)₃/C. Lithium ions could enhance the charge transfer during CDI desalination, while NaTi₂(PO₄)₃/C provided direct intercalation sites for sodium ions. The electrochemical capacities of the battery electrodes fitted well, which was favorable for the optimization of the desalination capacity. The low potential of the redox couple Ti³⁺/Ti⁴⁺ (−0.8 V versus Ag/AgCl) and intercalation/deintercalation behaviors of sodium ions that suppressed hydrogen evolution could enlarge the voltage window of the CDI process to 1.8 V. The novel CDI cell achieved an ultrahigh desalination capacity of 140.03 mg·g⁻¹ at 1.8 V with an initial salinity of 20 mM, revealing a new direction for the CDI performance enhancement. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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19 pages, 6030 KiB

Open AccessArticle

Characterization of Polyurethane Shape Memory Polymer and Determination of Shape Fixity and Shape Recovery in Subsequent Thermomechanical Cycles

by Maria Staszczak, Mana Nabavian Kalat, Karol Marek Golasiński, Leszek Urbański, Kohei Takeda, Ryosuke Matsui and Elżbieta Alicja Pieczyska

Polymers 2022, 14(21), 4775; https://doi.org/10.3390/polym14214775 - 07 Nov 2022

Cited by 18 | Viewed by 2863

Abstract

Multifunctional polyurethane shape memory polymers (PU-SMPs) have been of increasing interest in various applications. Here we report structure characterization, detailed methodology, and obtained results on the identification of functional properties of a thermoset PU-SMP (MP4510) with glass transition temperature of 45 °C. The [...] Read more.

Multifunctional polyurethane shape memory polymers (PU-SMPs) have been of increasing interest in various applications. Here we report structure characterization, detailed methodology, and obtained results on the identification of functional properties of a thermoset PU-SMP (MP4510) with glass transition temperature of 45 °C. The stable, chemically crosslinked network of this thermoset PU-SMP results in excellent shape memory behavior. Moreover, the proximity of the activation temperature range of this smart polymer to room and body temperature enables the PU-SMP to be used in more critical industrial applications, namely fast-response actuators. The thermomechanical behavior of a shape memory polymer determines the engineering applications of the material. Therefore, investigation of the shape memory behavior of this class of commercial PU-SMP is of particular importance. The conducted structural characterization confirms its shape memory properties. The shape fixity and shape recovery properties were determined by a modified experimental approach, considering the polymer’s sensitivity to external conditions, i.e., the temperature and humidity variations. Three thermomechanical cycles were considered and the methodology used is described in detail. The obtained shape fixity ratio of the PU-SMP was approximately 98% and did not change significantly in the subsequent cycles of the thermomechanical loading due to the stability of chemical crosslinks in the thermoset materials structure. The shape recovery was found to be approximately 90% in the first cycle and reached a value higher than 99% in the third cycle. The results confirm the effect of the thermomechanical training on the improvement of the PU-SMP shape recovery after the first thermomechanical cycle as well as the effect of thermoset material stability on the repeatability of the shape memory parameters quantities. Full article

(This article belongs to the Special Issue Structure and Mechanical Properties of Polymer Composites)

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16 pages, 6081 KiB

Open AccessArticle

Study on Degradation of 1,2,4-TrCB by Sugarcane Cellulose-TiO₂ Carrier in an Intimate Coupling of Photocatalysis and Biodegradation System

by Zhenqi Zhou, Chunlin Jiao, Yinna Liang, Ang Du, Jiaming Zhang, Jianhua Xiong, Guoning Chen, Hongxiang Zhu and Lihai Lu

Polymers 2022, 14(21), 4774; https://doi.org/10.3390/polym14214774 - 07 Nov 2022

Cited by 1 | Viewed by 1353

Abstract

1,2,4 trichlorobenzene (1,2,4-TrCB) is a persistent organic pollutant with chemical stability, biological toxicity, and durability, which has a significant adverse impact on the ecological environment and human health. In order to solve the pollution problem, bagasse cellulose is used as the basic framework [...] Read more.

1,2,4 trichlorobenzene (1,2,4-TrCB) is a persistent organic pollutant with chemical stability, biological toxicity, and durability, which has a significant adverse impact on the ecological environment and human health. In order to solve the pollution problem, bagasse cellulose is used as the basic framework and nano TiO₂ is used as the photocatalyst to prepare composite carriers with excellent performance. Based on this, an intimate coupling of photocatalysis and biodegradation (ICPB) system combining photocatalysis and microorganisms is constructed. We use the combined technology for the first time to deal with the pollution problem of 1,2,4-TrCB. The biofilm in the composite carrier can decompose the photocatalytic products so that the removal rate of 1,2,4-TrCB is 68.01%, which is 14.81% higher than those of biodegradation or photocatalysis alone, and the mineralization rate is 50.30%, which is 11.50% higher than that of photocatalysis alone. The degradation pathways and mechanisms of 1,2,4-TrCB are explored, which provide a theoretical basis and potential application for the efficient degradation of 1,2,4-TrCB and other refractory organics by the ICPB system. Full article

(This article belongs to the Special Issue Advances in the Preparation, Properties and Application of Polyurethane, Cellulose and Their Composites)

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11 pages, 4115 KiB

Open AccessArticle

A Flexible Piezoelectric Device for Frequency Sensing from PVDF/SWCNT Composite Fibers

by Sejin Choi, Jihwan Lim, Hansol Park and Han Seong Kim

Polymers 2022, 14(21), 4773; https://doi.org/10.3390/polym14214773 - 07 Nov 2022

Cited by 5 | Viewed by 2121

Abstract

Polymer piezoelectric devices have been widely studied as sensors, energy harvesters, and generators with flexible and simple processes. Flexible piezoelectric devices are sensitive to external stimuli and are attracting attention because of their potential and usefulness as acoustic sensors. In this regard, the [...] Read more.

Polymer piezoelectric devices have been widely studied as sensors, energy harvesters, and generators with flexible and simple processes. Flexible piezoelectric devices are sensitive to external stimuli and are attracting attention because of their potential and usefulness as acoustic sensors. In this regard, the frequency sensing of sound must be studied to use flexible piezoelectric devices as sensors. In this study, a flexible piezoelectric device composed of a polymer and an electrode was successfully fabricated. Polyvinylidene fluoride, the active layer of the piezoelectric device, was prepared by electrospinning, and electrodes were formed by dip−coating in a prepared single−walled carbon nanotube dispersion. The output voltage of the external sound was matched with the input frequency through a fast Fourier transform, and frequency matching was successfully performed, even with mechanical stimulation. In a high−frequency test, the piezoelectric effect and frequency domain peak started to decrease sharply at 300 Hz, and the limit of the piezoelectric effect and sensing was observed from 800 Hz. The results of this study suggest a method for developing flexible piezoelectric-fiber frequency sensors based on piezoelectric devices for acoustic sensor systems. Full article

(This article belongs to the Special Issue Polymer-Based Materials for Sensors)

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10 pages, 3119 KiB

Open AccessArticle

Hyaluronic Acid Modified Au@SiO₂@Au Nanoparticles for Photothermal Therapy of Genitourinary Tumors

by Ruizhi Wang, Nan Du, Liang Jin, Wufei Chen, Zhuangxuan Ma, Tianyu Zhang, Jie Xu, Wei Zhang, Xiaolin Wang and Ming Li

Polymers 2022, 14(21), 4772; https://doi.org/10.3390/polym14214772 - 07 Nov 2022

Cited by 7 | Viewed by 1912

Abstract

Bladder cancer and prostate cancer are the most common malignant tumors of the genitourinary system. Conventional strategies still face great challenges of high recurrence rate and severe trauma. Therefore, minimally invasive photothermal therapy (PTT) has been extensively explored to address these challenges. Herein, [...] Read more.

Bladder cancer and prostate cancer are the most common malignant tumors of the genitourinary system. Conventional strategies still face great challenges of high recurrence rate and severe trauma. Therefore, minimally invasive photothermal therapy (PTT) has been extensively explored to address these challenges. Herein, fluorescent Au nanoparticles (NPs) were first prepared using glutathione as template, which were then capped with SiO₂ shell to improve the biocompatibility. Next, Au nanoclusters were deposited on the NPs surface to obtain Au@SiO₂@Au NPs for photothermal conversion. The gaps between Au nanoparticles on their surface could enhance their photothermal conversion efficiency. Finally, hyaluronic acid (HA), which targets cancer cells overexpressing CD44 receptors, was attached on the NPs surface via 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) chemistry to improve the accumulation of NPs in tumor tissues. Photothermal experiments showed that NPs with an average size of 37.5 nm have a high photothermal conversion efficiency (47.6%) and excellent photostability, thus exhibiting potential application as a PTT agent. The temperature of the NPs (100 μg·mL⁻¹) could rapidly increase to 38.5 °C within 200 s and reach the peak of 57.6 °C with the laser power density of 1.5 W·cm⁻² and irradiation time of 600 s. In vivo and in vitro PTT experiments showed that the NPs have high biocompatibility and excellent targeted photothermal ablation capability of cancer cells. Both bladder and prostate tumors disappeared at 15 and 18 d post-treatment with HA-Au@SiO₂@Au NPs, respectively, and did not recur. In summary, HA-Au@SiO₂@Au NPs can be used a powerful PTT agent for minimally invasive treatment of genitourinary tumors. Full article

(This article belongs to the Special Issue Self-Assembly of Polymers: Towards Multiscale Functional Materials for Bioapplications)

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19 pages, 55990 KiB

Open AccessArticle

Fundamental Structural and Kinetic Principals of High Strength UHMWPE Fibers Production by Gel-Technology

by Elena Ivan’kova, Viktor Egorov, Vyacheslav Marikhin, Liubov Myasnikova, Yuri Boiko and Elena Radovanova

Polymers 2022, 14(21), 4771; https://doi.org/10.3390/polym14214771 - 07 Nov 2022

Cited by 5 | Viewed by 1664

Abstract

One of the main research work in the field of polymeric materials was, is and always will be the improvement of their mechanical properties. Comprehensive structural studies of UHMWPE reactor powder, the features of its dissolution and the formation of a gel-state, as [...] Read more.

One of the main research work in the field of polymeric materials was, is and always will be the improvement of their mechanical properties. Comprehensive structural studies of UHMWPE reactor powder, the features of its dissolution and the formation of a gel-state, as well as UHMWPE films oriented up to various draw ratios, were carried out using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. For comparison, decalin and vaseline oil were chosen as solvents. The mechanical properties of oriented UHMWPE films were also studied. In the process of orientation drawing, basing on the developed structural-kinetic principles of strengthening for highly oriented speciments gel-cast from UHMWPE powders, the average values of tensile strength of 4.7 GPa (about 6% of the samples had strength values up to 6.0 GPa) and an Young’s modulus of 170 GPa (about 6% of the samples had Young’s modulus values of 200 GPa). These values are among the highest according to the world scientific literature. A significant increase in the mechanical characteristics of highly oriented UHMWPE films was achieved using experimentally confirmed scientific approaches to revealing the structure-property relationship at each stage of the gel process. Full article

(This article belongs to the Special Issue Synthesis of Polymer Membranes and Their Applications)

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14 pages, 1399 KiB

Open AccessReview

A Review on the Role of Earthworms in Plastics Degradation: Issues and Challenges

by Shahad Khaldoon, Japareng Lalung, Umrana Maheer, Mohamad Anuar Kamaruddin, Mohd Firdaus Yhaya, Eman S. Alsolami, Hajer S. Alorfi, Mahmoud A. Hussein and Mohd Rafatullah

Polymers 2022, 14(21), 4770; https://doi.org/10.3390/polym14214770 - 07 Nov 2022

Cited by 6 | Viewed by 3216

Abstract

Recently, the contribution of earthworms to plastic degradation and their capability to swallow smaller plastic fragments, known as microplastics, has been emphasized. The worm physically changes the size of microplastics and enhances microbial activities to increase the possibility of degradation. However, no research [...] Read more.

Recently, the contribution of earthworms to plastic degradation and their capability to swallow smaller plastic fragments, known as microplastics, has been emphasized. The worm physically changes the size of microplastics and enhances microbial activities to increase the possibility of degradation. However, no research has shown that earthworms can chemically degrade microplastics to an element form, CO₂ or H₂O. In this review, previous research has been thoroughly explored to analyse the role that earthworms could play in plastic degradation in the soil. Earthworms can significantly affect the physical characteristics of plastics. However, earthworms’ abilities to chemically degrade or change the chemical structure of plastics and microplastics have not been observed. Additionally, earthworms exhibit selective feeding behaviour, avoiding areas containing a high plastics concentration and rejecting plastics. Consequently, earthworms’ abilities to adapt to the microplastics in soil in the environment can cause a problem. Based on this review, the challenges faced in earthworm application for plastic degradation are mostly expected to be associated with the toxicity and complexity of the plastic material and environmental factors, such as the moisture content of the soil and its temperature, microbial population, and feeding method. Full article

(This article belongs to the Special Issue Degradation and Stabilization of Polymer Materials)

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15 pages, 4873 KiB

Open AccessArticle

Enhanced Soft Sensor with Qualified Augmented Samples for Quality Prediction of the Polyethylene Process

by Yun Dai, Angpeng Liu, Meng Chen, Yi Liu and Yuan Yao

Polymers 2022, 14(21), 4769; https://doi.org/10.3390/polym14214769 - 07 Nov 2022

Cited by 1 | Viewed by 1382

Abstract

Data-driven soft sensors have increasingly been applied for the quality measurement of industrial polymerization processes in recent years. However, owing to the costly assay process, the limited labeled data available still pose significant obstacles to the construction of accurate models. In this study, [...] Read more.

Data-driven soft sensors have increasingly been applied for the quality measurement of industrial polymerization processes in recent years. However, owing to the costly assay process, the limited labeled data available still pose significant obstacles to the construction of accurate models. In this study, a novel soft sensor named the selective Wasserstein generative adversarial network, with gradient penalty-based support vector regression (SWGAN-SVR), is proposed to enhance quality prediction with limited training samples. Specifically, the Wasserstein generative adversarial network with gradient penalty (WGAN-GP) is employed to capture the distribution of the available limited labeled data and to generate virtual candidates. Subsequently, an effective data-selection strategy is developed to alleviate the problem of varied-quality samples caused by the unstable training of the WGAN-GP. The selection strategy includes two parts: the centroid metric criterion and the statistical characteristic criterion. An SVR model is constructed based on the qualified augmented training data to evaluate the prediction performance. The superiority of SWGAN-SVR is demonstrated, using a numerical example and an industrial polyethylene process. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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24 pages, 9358 KiB

Open AccessArticle

Application Research on the Lightweight Design and Optimization of Carbon Fiber Reinforced Polymers (CFRP) Floor for Automobile

by Shuai Zhang, Hao Song, Liyou Xu and Kefang Cai

Polymers 2022, 14(21), 4768; https://doi.org/10.3390/polym14214768 - 07 Nov 2022

Cited by 4 | Viewed by 1835

Abstract

In order to improve the lightweight level of the automotive floor, reduce material application cost, and improve integrated process manufacturing performance through structural design and optimization, this article proposes a design method to link conceptual design and detailed design and optimize the composite [...] Read more.

In order to improve the lightweight level of the automotive floor, reduce material application cost, and improve integrated process manufacturing performance through structural design and optimization, this article proposes a design method to link conceptual design and detailed design and optimize the composite floor by combining free size optimization and size optimization methods. The basic theory of composite mechanics is expounded from the stress-strain theory of single-layer plates, and the stiffness and strength theory of laminated plates, which provides theoretical support for the structural design, material design, and allowable value design of composites. The mechanical properties of CFRP were tested to obtain the basic material parameters of CFRP T300/5208. With the material parameters, the CFRP floor super layers are established in Optistruct software. The shape of the floor super layers is optimized by using the free size optimization method, with the body-in-white (BIW) lightweight coefficient as the objective and the BIW performance as the constraints. The BIW lightweight coefficient is reduced from 4.35 to 4.20 after free size optimization, and the layer blocks shape is obtained and clipped based on engineering application. With the floor mass as the objective and the BIW performance as the constraints, the size optimization of the floor layer blocks thickness is optimized. Then the number of floor layers is obtained, and the CFRP floor is established in Fibersim software. Use the simulation analysis method to compare and verify the performance of the floor before and after optimization. The results show that the failure index of the floor is far less than the failure standard, while the mass of the CFRP floor is reduced by 6.8 kg compared with the original steel floor, which an improvement rate reaching 27.5%. The design and optimization methods presented in this article provide a reference for the design and application of the CFRP floor. Full article

(This article belongs to the Section Polymer Applications)

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19 pages, 7325 KiB

Open AccessArticle

Construction of an Electrical Conductor, Strain Sensor, Electrical Connection and Cycle Switch Using Conductive Graphite Cotton Fabrics

by Fahad Alhashmi Alamer, Asal Aldeih, Omar Alsalmi, Khalid Althagafy and Mawaheb Al-Dossari

Polymers 2022, 14(21), 4767; https://doi.org/10.3390/polym14214767 - 07 Nov 2022

Cited by 5 | Viewed by 1651

Abstract

Researchers in science and industry are increasingly interested in conductive textiles. In this article, we have successfully prepared conductive textiles by applying a graphite dispersion to cotton fabric using a simple brush-coating-drying method and the solvents of dimethyl sulfoxide, dimethyl formamide, and a [...] Read more.

Researchers in science and industry are increasingly interested in conductive textiles. In this article, we have successfully prepared conductive textiles by applying a graphite dispersion to cotton fabric using a simple brush-coating-drying method and the solvents of dimethyl sulfoxide, dimethyl formamide, and a solvent mixture of both. The sheet resistance of the resulting cotton fabrics could be influenced by the type of polar solvent used to prepare the graphite dispersion and the concentration of graphite. In addition, the graphite cotton fabrics showed semiconductive behavior upon studying the resistance at different temperatures. A flexible strain sensor was fabricated using these graphite cotton fabrics for human motion detection. Most importantly, the resulting strain sensor functions even after 100 bending cycles, indicating its excellent reproducibility. In addition, our results have also shown that these graphite cotton fabrics can be used as electrical interconnects in electrical circuits without any visible degradation of the conductive cotton. Finally, a cotton electrical cycle switch was made using the graphite cotton fabrics and worked in the on and off state. Full article

(This article belongs to the Special Issue Polymers’ Role in Sensors: Resistant Solid Supports or Multi-Purpose Sensing Units?)

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13 pages, 5552 KiB

Open AccessArticle

Effect of the Current on the Fire Characteristics of Overloaded Polyvinyl Chloride Copper Wires

by Zhe Li, Qingwen Lin, Yang Li, Huifei Lyu, Huaibin Wang and Junli Sun

Polymers 2022, 14(21), 4766; https://doi.org/10.3390/polym14214766 - 07 Nov 2022

Cited by 2 | Viewed by 1410

Abstract

In this study, the fire behavior variation of unenergized polyvinyl chloride (PVC) copper wires subjected to overload with different currents was investigated by a cone calorimeter. Overload currents were selected from 1 times safe-rated current (I_e) to 3.5 times I [...] Read more.

In this study, the fire behavior variation of unenergized polyvinyl chloride (PVC) copper wires subjected to overload with different currents was investigated by a cone calorimeter. Overload currents were selected from 1 times safe-rated current (I_e) to 3.5 times I_e to obtain tested sample wires. The mass fraction, time to ignition (TTI), heat release rate (HRR), gas emission, and residue were measured. If the current flowing through the wire increased up to 3.5 times I_e, the TTI of this unenergized wire increased drastically and the peak HRR (pHRR) decreased notably so that the flame growing index (FGI) reduced considerably. When the wire carried less than three times I_e, the FGI remained stable. For all overloaded PVC copper wires, the increase in the heat flux resulted in a higher pHRR and a lower burning duration. However, regardless of the external heat flux exposure, the FGI of copper wires overloaded at 3.5 times I_e was lower than that of copper wires carrying less than other times I_e. Moreover, the consumption of O₂ and generation of CO₂ as the heat flux varied were consistent with that of the HRR. Opposed to expectation, the flame propagation of unenergized PVC copper wires would decline in a fire, if the wire has been damaged by overload with some currents. Full article

(This article belongs to the Collection Fire and Polymers)

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15 pages, 1520 KiB

Open AccessArticle

Electrospun Polycrown Ether Composite Nanofibers as an Adsorbent for On-Line Solid Phase Extraction of Eight Bisphenols from Drinking Water Samples with Column-Switching Prior to High Performance Liquid Chromatography

by Tong Xu, Rui Zhang, Yueling Bi, Jingjing Li, Xiaohuan Li, Liqin Chen and Zhongze Fang

Polymers 2022, 14(21), 4765; https://doi.org/10.3390/polym14214765 - 07 Nov 2022

Cited by 3 | Viewed by 1264

Abstract

Bisphenols (BPs) are a class of endocrine disruptors widely existing in the environment. They have a great impact on human health owing to their environmental endocrine disrupting effects, chronic toxicity, neurotoxicity, cytotoxicity and genetic toxicity. In this paper, an on-line packed fiber solid [...] Read more.

Bisphenols (BPs) are a class of endocrine disruptors widely existing in the environment. They have a great impact on human health owing to their environmental endocrine disrupting effects, chronic toxicity, neurotoxicity, cytotoxicity and genetic toxicity. In this paper, an on-line packed fiber solid phase extraction (PFSPE) coupling with column-switching HPLC-FLD determination method was developed for the determination of eight BPs in drinking water. The poly (dibenzo-18-crown-6-ether)/polystyrene composite nanofibers (PDB18C6/PS) were prepared by electrospinning and used as an adsorbent for the on-line PFSPE column. The on-line PFSPE-HPLC equipment contained a dual ternary pump and a switching valve to enable enrichment, purification, and analysis directly in the system. The results showed that the proposed on-line PFSPE-HPLC-FLD method realized the simultaneous separation and detection of eight BPs: BPF, BPE, BPA, BPB, BPAF, BPAP, BPC and BPZ. The curves of the target analytes were prepared with good correlation coefficient values (r² > 0.998) in the range of 50–1000 pg/mL. The limit of detection (S/N = 3) was 20 pg/mL, the limit of quantitation (S/N = 10) is 50 pg/mL. The recoveries of eight BPs were 94.8–127.3%, and the intra-day precisions (RSD) were less than 10%. The PFSPE column made of the PDB18C6/PS composite nanofibers has stable properties and can be reused at least 200 times. In the detection of drinking water samples, BPZ was detected in nearly 80% of drinking water samples, and BPA, BPAP, BPF and BPAF were also detected in some water samples. This high level of integration and automation was achieved in pretreatment of eight BPs from water samples. The proposed simple, rapid, and practical method has been successfully applied to the detection of eight BPs in drinking water, which can provide powerful technical support for drinking water quality and safety monitoring. Full article

(This article belongs to the Special Issue Nanostructured Polymers for Energy and Environmental Applications)

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16 pages, 4789 KiB

Open AccessArticle

A Polytetrafluoroethylene (PTFE) and Nano-Al₂O₃ Based Composite Coating with a Bacteriostatic Effect against E. coli and Low Cytotoxicity

by Dmitriy E. Burmistrov, Dmitriy A. Serov, Aleksander V. Simakin, Ilya V. Baimler, Oleg V. Uvarov and Sergey V. Gudkov

Polymers 2022, 14(21), 4764; https://doi.org/10.3390/polym14214764 - 07 Nov 2022

Cited by 6 | Viewed by 2266

Abstract

The problem of bacterial contamination through surfaces is important for the food industry. In this regard, there is a growing interest in new coatings based on nanoparticles that can provide a long-term antibacterial effect. Aluminum oxide nanoparticles are a good candidate for such [...] Read more.

The problem of bacterial contamination through surfaces is important for the food industry. In this regard, there is a growing interest in new coatings based on nanoparticles that can provide a long-term antibacterial effect. Aluminum oxide nanoparticles are a good candidate for such coatings due to their availability and good biocompatibility. In this study, a coating containing aluminum oxide nanoparticles was produced using polytetrafluoroethylene as a polymer matrix—a polymer that exhibits excellent mechanical and physicochemical properties and it is not toxic. The obtained coatings based on “liquid Teflon” containing various concentrations of nanoparticles (0.001–0.1 wt%) prevented the bacterial growth, and they did not exhibit a cytotoxicity on animal cells in vitro. Such coatings are designed not only to provide an antibacterial surface effect, but also to eliminate micro damages on surfaces that inevitably occur in the process of food production. Full article

(This article belongs to the Special Issue Advance in Functional Biological Polymer Membranes)

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25 pages, 5793 KiB

Open AccessReview

Polymerization in the Borstar Polypropylene Hybrid Process: Combining Technology and Catalyst for Optimized Product Performance

by Michiel F. Bergstra, Peter Denifl, Markus Gahleitner, Dusan Jeremic, Vasileios Kanellopoulos, Daniela Mileva, Pavel Shutov, Vasileios Touloupidis and Cornelia Tranninger

Polymers 2022, 14(21), 4763; https://doi.org/10.3390/polym14214763 - 07 Nov 2022

Cited by 2 | Viewed by 5629

Abstract

Producing isotactic polypropylene (iPP) homo- and copolymers in a wide composition and property range according to customer demand requires perfect alignment between the process technology, catalyst system and polymer structure. The present review shows this for the Borstar^® PP process, a hybrid [...] Read more.

Producing isotactic polypropylene (iPP) homo- and copolymers in a wide composition and property range according to customer demand requires perfect alignment between the process technology, catalyst system and polymer structure. The present review shows this for the Borstar^® PP process, a hybrid process employing liquid bulk and gas phase stages, in an exemplary way. It starts with the process design and continues through two generations of Ziegler–Natta catalyst development history to the design of advanced multimodal random and multiphase copolymers. Essential elements of each of the three areas contributing to performance range are highlighted, and an outlook to future development is given. Full article

(This article belongs to the Collection Design and Synthesis of Polymers)

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13 pages, 492 KiB

Open AccessArticle

Self-Attractive Semiflexible Polymers under an External Force Field

by Antonio Lamura

Polymers 2022, 14(21), 4762; https://doi.org/10.3390/polym14214762 - 07 Nov 2022

Viewed by 1195

Abstract

The dynamical response of a tethered semiflexible polymer with self-attractive interactions and subjected to an external force field is numerically investigated by varying stiffness and self-interaction strength. The chain is confined in two spatial dimensions and placed in contact with a heat bath [...] Read more.

The dynamical response of a tethered semiflexible polymer with self-attractive interactions and subjected to an external force field is numerically investigated by varying stiffness and self-interaction strength. The chain is confined in two spatial dimensions and placed in contact with a heat bath described by the Brownian multi-particle collision method. For strong self-attraction the equilibrium conformations range from compact structures to double-stranded chains, and to rods when increasing the stiffness. Under the external field at small rigidities, the initial close-packed chain is continuously unwound by the force before being completely elongated. For double-stranded conformations the transition from the folded state to the open one is sharp being steeper for larger stiffnesses. The discontinuity in the transition appears in the force-extension relation, as well as in the probability distribution function of the gyration radius. The relative deformation with respect to the equilibrium case along the direction normal to the force is found to decay as the inverse of the applied force. Full article

(This article belongs to the Special Issue Feature Papers in Polymer Physics and Theory)

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17 pages, 4128 KiB

Open AccessArticle

Coarse-Grained Simulations of Release of Drugs Housed in Flexible Nanogels: New Insights into Kinetic Parameters

by Manuel Quesada-Pérez, Luis Pérez-Mas, David Carrizo-Tejero, José-Alberto Maroto-Centeno, María del Mar Ramos-Tejada and Alberto Martín-Molina

Polymers 2022, 14(21), 4760; https://doi.org/10.3390/polym14214760 - 07 Nov 2022

Cited by 4 | Viewed by 1273

Abstract

The diffusion-controlled release of drugs housed in flexible nanogels has been simulated with the help of a coarse-grained model that explicitly considers polymer chains. In these in silico experiments, the effect of its flexibility is assessed by comparing it with data obtained for [...] Read more.

The diffusion-controlled release of drugs housed in flexible nanogels has been simulated with the help of a coarse-grained model that explicitly considers polymer chains. In these in silico experiments, the effect of its flexibility is assessed by comparing it with data obtained for a rigid nanogel with the same volume fraction and topology. Our results show that the initial distribution of the drug can exert a great influence on the release kinetics. This work also reveals that certain surface phenomena driven by steric interactions can lead to apparently counterintuitive behaviors. Such phenomena are not usually included in many theoretical treatments used for the analysis of experimental release kinetics. Therefore, one should be very careful in drawing conclusions from these formalisms. In fact, our results suggest that the interpretation of drug release curves in terms of kinetic exponents (obtained from the Ritger–Peppas Equation) is a tricky question. However, such curves can provide a first estimate of the drug diffusion coefficient. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials for Pharmaceutical Applications III)

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17 pages, 1886 KiB

Open AccessArticle

Mechanical Properties and Coagulation Characteristics of Flue Gas Desulfurization Gypsum-Based Polymer Materials

by Mingjing Li, Guodong Huang, Bo Wang, Yi Cui, Binbin Chang, Qiaoqiao Yin, Ming Ge, Shuwei Zhang, Qi Wang and Jiacheng Feng

Polymers 2022, 14(21), 4761; https://doi.org/10.3390/polym14214761 - 06 Nov 2022

Cited by 1 | Viewed by 1371

Abstract

To resolve problems caused by the accumulation of flue gas desulfurization gypsum (FGDG) in the environment, a polymer material was prepared using FGDG, granulated blast furnace slag (GBFS), fly ash (FA), and solid sodium silicate (SSS). The compressive strength of these polymer specimens [...] Read more.

To resolve problems caused by the accumulation of flue gas desulfurization gypsum (FGDG) in the environment, a polymer material was prepared using FGDG, granulated blast furnace slag (GBFS), fly ash (FA), and solid sodium silicate (SSS). The compressive strength of these polymer specimens cured for 3, 28, and 60 d was regularly measured, and their condensation behavior was analyzed. Both the formation behavior of mineral crystals and microstructure characteristics were analyzed further using X-ray diffraction and scanning electron microscopy. The compressive strength of pure FGDG polymer specimen (whose strength is generated by particle condensation crystallization) is insufficient and the condensation is slow. The addition of appropriate amounts of GBFS, FA, and SSS can continuously and considerably improve the compressive strength and shorten the setting time. The optimal proportions of FGDG, GBFS, and FA are 50%, 20%, and 30%, respectively, with the SSS addition amount of 20 g. The incorporation of GBFS, FA, and SSS can promote the polymerization of calcium, silicon, and aluminum in FGDG to form silicate and aluminosilicate minerals. Their formation is the main reason for the increased compressive strength and accelerated coagulation. Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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18 pages, 1242 KiB

Open AccessArticle

Alginate Particles for Encapsulation of Phenolic Extract from Spirulina sp. LEB-18: Physicochemical Characterization and Assessment of In Vitro Gastrointestinal Behavior

by Adriana R. Machado, Pedro M. P. Silva, António A. Vicente, Leonor A. Souza-Soares, Ana C. Pinheiro and Miguel A. Cerqueira

Polymers 2022, 14(21), 4759; https://doi.org/10.3390/polym14214759 - 06 Nov 2022

Cited by 7 | Viewed by 2744

Abstract

Encapsulation can be used as a strategy to protect and control the release of bioactive extracts. In this work, an extract from Spirulina sp. LEB-18, rich in phenolic compounds, was encapsulated in biopolymeric particles (i.e., composed of alginate) and characterized concerning their thermal [...] Read more.

Encapsulation can be used as a strategy to protect and control the release of bioactive extracts. In this work, an extract from Spirulina sp. LEB-18, rich in phenolic compounds, was encapsulated in biopolymeric particles (i.e., composed of alginate) and characterized concerning their thermal behavior using differential scanning calorimetry (DSC), size, morphology, swelling index (S), and encapsulation efficiency (EE%); the release profile of the phenolic compounds at different pHs and the particle behavior under in vitro gastrointestinal digestion were also evaluated. It was shown that it is possible to encapsulate the phenolic extract from Spirulina sp. LEB-18 in alginate particles with high encapsulation efficiency (88.97%). It was also observed that the particles are amorphous and that the encapsulated phenolic compounds were released at a pH 7.2 but not at pH 1.5, which means that the alginate particles are able to protect the phenolic compounds from the harsh stomach conditions but lose their integrity under intestinal pH conditions. Regarding bioaccessibility, it was observed that the encapsulated phenolic compounds showed higher bioaccessibility compared to phenolic compounds in free form. This work increases the knowledge about the behavior of alginate particles encapsulating phenolic compounds during in vitro gastrointestinal digestion. It also provides essential information for designing biopolymeric particle formulations encapsulating phenolic compounds for application in pharmaceutical and food products. Full article

(This article belongs to the Special Issue Recent Advances in Bioactive Molecules Delivery)

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17 pages, 5489 KiB

Open AccessArticle

Solvent Evaporation Rate as a Tool for Tuning the Performance of a Solid Polymer Electrolyte Gas Sensor

by Petr Sedlak, Pavel Kaspar, Dinara Sobola, Adam Gajdos, Jiri Majzner, Vlasta Sedlakova and Petr Kubersky

Polymers 2022, 14(21), 4758; https://doi.org/10.3390/polym14214758 - 06 Nov 2022

Viewed by 1646

Abstract

Solid polymer electrolytes show their potential to partially replace conventional electrolytes in electrochemical devices. The solvent evaporation rate represents one of many options for modifying the electrode–electrolyte interface by affecting the structural and electrical properties of polymer electrolytes used in batteries. This paper [...] Read more.

Solid polymer electrolytes show their potential to partially replace conventional electrolytes in electrochemical devices. The solvent evaporation rate represents one of many options for modifying the electrode–electrolyte interface by affecting the structural and electrical properties of polymer electrolytes used in batteries. This paper evaluates the effect of solvent evaporation during the preparation of solid polymer electrolytes on the overall performance of an amperometric gas sensor. A mixture of the polymer host, solvent and an ionic liquid was thermally treated under different evaporation rates to prepare four polymer electrolytes. A carbon nanotube-based working electrode deposited by spray-coating the polymer electrolyte layer allowed the preparation of the electrode–electrolyte interface with different morphologies, which were then investigated using scanning electron microscopy and Raman spectroscopy. All prepared sensors were exposed to nitrogen dioxide concentration of 0–10 ppm, and the current responses and their fluctuations were analyzed. Electrochemical impedance spectroscopy was used to describe the sensor with an equivalent electric circuit. Experimental results showed that a higher solvent evaporation rate leads to lower sensor sensitivity, affects associated parameters (such as the detection/quantification limit) and increases the limit of the maximum current flowing through the sensor, while the other properties (hysteresis, repeatability, response time, recovery time) change insignificantly. Full article

(This article belongs to the Special Issue Advanced Polymer-Based Sensors Materials)

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