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17 pages, 17951 KiB

Open AccessArticle

Dialdehyde Starch as a Cross-Linking Agent Modifying Fish Collagen Film Properties

by Patrycja Brudzyńska, Karolina Kulka-Kamińska, Łukasz Piwowarski, Katarzyna Lewandowska and Alina Sionkowska

Materials 2024, 17(7), 1475; https://doi.org/10.3390/ma17071475 - 23 Mar 2024

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Abstract

The aim of this research was the modification of fish collagen films with various amounts of dialdehyde starch (DAS). Film properties were examined before and after the cross-linking process by DAS. Prepared biopolymer materials were characterized by Fourier Transform Infrared Spectroscopy and Atomic [...] Read more.

The aim of this research was the modification of fish collagen films with various amounts of dialdehyde starch (DAS). Film properties were examined before and after the cross-linking process by DAS. Prepared biopolymer materials were characterized by Fourier Transform Infrared Spectroscopy and Atomic Force Microscopy. Moreover, the mechanical, thermal and swelling properties of the films were evaluated and the contact angle was measured. Research has shown that dialdehyde starch applied as a cross-linking agent influences collagen film properties. Mechanical testing indicated a decrease in Young’s Modulus and an increase in breaking force, elongation at break, and tensile strength parameters. Results for contact angle were significantly higher for collagen films cross-linked with DAS; thus, the hydrophilicity of samples decreased. Modified samples presented a lower swelling degree in PBS than native collagen films. However, the highest values for the degree of swelling among the modified specimens were obtained from the 1% DAS samples, which were 717% and 702% for 1% and 2% collagen, respectively. Based on AFM images and roughness values, it was noticed that DAS influenced collagen film surface morphology. The lowest value of Rq was observed for 2%Coll_2%DAS and was approximately 10 nm. Analyzing thermograms for collagen samples, it was observed that pure collagen samples were less thermally stable than cross-linked ones. Dialdehyde starch is a promising cross-linking agent for collagen extracted from fish skin and may increase its applicability. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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11 pages, 8256 KiB

Open AccessArticle

A Preliminary Investigation on a Water- and Acetone-Based Solvolysis Recycling Process for CFRPs

by Christina Vogiantzi and Konstantinos Tserpes

Materials 2024, 17(5), 1102; https://doi.org/10.3390/ma17051102 - 28 Feb 2024

Viewed by 434

Abstract

Composites, and especially carbon-fiber-reinforced plastics (CFRPs), are increasingly used in the automotive, aerospace, and aviation industries, and as a result, CFRP production has increased dramatically, leading to a corresponding increase in waste. Landfills and the incineration of waste are likely to be restricted [...] Read more.

Composites, and especially carbon-fiber-reinforced plastics (CFRPs), are increasingly used in the automotive, aerospace, and aviation industries, and as a result, CFRP production has increased dramatically, leading to a corresponding increase in waste. Landfills and the incineration of waste are likely to be restricted as a result of legislation, thus highlighting the need for efficient recycling methods for CFRPs. However, the recycling of CFRPs is very challenging, mainly due to the difficulty of removing their thermosetting matrix. This study reports a pre-screening of the solvolysis recycling process for CFRPs based on the mechanical properties of the recovered fibers. To this end, solvolysis tests were conducted on unidirectional CFRP samples under supercritical and subcritical conditions using acetone and water. The solvolysis tests were conducted for various conditions of temperature, pressure, and reaction time, without the use of any catalyst. Also, the loading rate (volume of solvent/volume of reactor) was constant. The efficiency of the recycling processes has been evaluated through a morphological and a mechanical characterization of the recovered fibers. In most cases, the decomposition efficiency of the epoxy resin, measured in terms of mass, ranged between 90 and 100%. Moreover, the scanning electron microscopy images of the recovered fibers showed negligible traces of resin residues and no detectable signs of physical damage or any changes in morphology with regard to diameter. Finally, the single-fiber tension tests revealed that that the recovered fibers retained more than 61% of their initial Young’s modulus and 70% of their tensile strength. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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15 pages, 5729 KiB

Open AccessArticle

New Biodegradable Copolymers Based on Betulin and Hydroxycarboxylic Acid Derivatives

by Alexey Zinovyev, Alina Gorbunova, Anna Chernova, Sónia A. C. Carabineiro, Ekaterina Poletykina, Anastasia Bugaeva, Viktor Novikov, Ekaterina Kolobova and Alexey Pestryakov

Materials 2024, 17(5), 981; https://doi.org/10.3390/ma17050981 - 20 Feb 2024

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Abstract

In this study, we propose an approach to the synthesis of new biodegradable polymer materials based on renewable raw feedstock (betulin) and derivatives of hydroxycarboxylic acids using a catalyst/catalytic system (γ-Al₂O₃, γ-Al₂O₃/TBHP) that is safe [...] Read more.

In this study, we propose an approach to the synthesis of new biodegradable polymer materials based on renewable raw feedstock (betulin) and derivatives of hydroxycarboxylic acids using a catalyst/catalytic system (γ-Al₂O₃, γ-Al₂O₃/TBHP) that is safe for health and the environment. The resulting polymers are linear thermoplastic polymers that undergo collapse upon melting in the presence of atmospheric oxygen. Moreover, these polymers demonstrate non-toxicity towards a range of Gram-positive and Gram-negative bacteria. The polycondensation of betulin with butyl lactate is particularly noteworthy. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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16 pages, 6808 KiB

Open AccessArticle

The Effect of Colloidal Nanoparticles on Phase Separation of Block and Heteroarm Star Copolymers Confined between Polymer Brushes

by Minna Sun, Wenyu Chen, Lei Qin and Xu-Ming Xie

Materials 2024, 17(4), 804; https://doi.org/10.3390/ma17040804 - 07 Feb 2024

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Abstract

The effect of colloidal nanoparticles on the phase changes of the amphiphilic AB linear diblock, A₁A₂B, and A₂B heteroarm star copolymers confined between two polymer brush substrates was investigated by using a real-space self-consistent field theory. By [...] Read more.

The effect of colloidal nanoparticles on the phase changes of the amphiphilic AB linear diblock, A₁A₂B, and A₂B heteroarm star copolymers confined between two polymer brush substrates was investigated by using a real-space self-consistent field theory. By changing the concentrations of nanoparticles and polymer brushes, the phase structure of the amphiphilic AB copolymer transforms from lamellar to core-shell hexagonal phase to cylinder phase. The pattern of A₂B heteroarm star copolymer changes from core-shell hexagonal phases to lamellar phases and the layer decreases when increasing the density of the polymer brushes. The results showed that the phase behavior of the system is strongly influenced by the polymer brush architecture and the colloidal nanoparticle numbers. The colloidal nanoparticles and the soft confined surface of polymer brushes make amphiphilic AB copolymers easier to form ordered structures. The dispersion of the nanoparticles was also investigated in detail. The soft surfaces of polymer brushes and the conformation of the block copolymers work together to force the nanoparticles to disperse evenly. It will give helpful guidance for making some new functional materials by nano etching technology, nano photoresist, and nanoprinting. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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17 pages, 7995 KiB

Open AccessArticle

Sustainable Polypropylene-Based Composites with Agro-Waste Fillers: Thermal, Morphological, Mechanical Properties and Dimensional Stability

by Tatiana Zhiltsova, Jéssica Campos, Andreia Costa and Mónica S. A. Oliveira

Materials 2024, 17(3), 696; https://doi.org/10.3390/ma17030696 - 01 Feb 2024

Cited by 1 | Viewed by 766

Abstract

Natural fiber composites (NFC) are eco-friendly alternatives to synthetic polymers. However, some intrinsic natural fillers’ properties hinder their widespread implementation as reinforcement in polymeric matrices and require further investigation. In the scope of this study, the thermal, rheologic, mechanical (tension and flexural modes), [...] Read more.

Natural fiber composites (NFC) are eco-friendly alternatives to synthetic polymers. However, some intrinsic natural fillers’ properties hinder their widespread implementation as reinforcement in polymeric matrices and require further investigation. In the scope of this study, the thermal, rheologic, mechanical (tension and flexural modes), and morphological properties, as well as the water absorption and dimensional stability of the NF polypropylene (PP)-based injection molded composites reinforced with rice husk (rh) and olive pits (op) of 20 wt.% and 30% wt.%, respectively, were investigated. The results suggest that the higher content of the rice husk and olive pits led to a similar reduction in the melt flow index (MFI), independent of the additive type compared to virgin polypropylene (PPv). The melting and crystallization temperatures of the PPrh and PPop composites did not change with statistical significance. The composites are stiffer than the PP matrix by up to 49% and possess higher mechanical strength in the tension mode at the expense of decreased ductility. PPrh and PPop have a superior flexural modulus in the bending mode, while the flexural strength improvement was accomplished for the PP30%rh. The influence of the fibers’ distribution in the bulk of the parts on their mechanical performance was confirmed based on a non-localized morphology evaluation, which constitutes a novelty of the presented research. The dimensional stability of the composites was improved as the linear shrinkage in the flow direction was decreased by 49% for PPrh and 30% for PPop, positively correlating with an increase in the filler content and stiffness. PPop was less susceptible to water sorption than PPrh due to fibers’ composition and larger surface-to-area volume ratios. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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13 pages, 2529 KiB

Open AccessArticle

Design, Synthesis, and Spectral Properties of Novel 2-Mercaptobenzothiazole Derivatives

by Agnieszka Skotnicka and Janina Kabatc-Borcz

Materials 2024, 17(1), 246; https://doi.org/10.3390/ma17010246 - 02 Jan 2024

Viewed by 707

Abstract

This paper is focused on the optimalization of methods for the synthesis, isolation, and purification of 2-mercaptobenzothiazole-based acrylic and methacrylic monomers. The structures of the newly synthesized compounds were confirmed through infrared (IR) and nuclear magnetic resonance spectroscopy (NMR). Spectroscopic properties of the [...] Read more.

This paper is focused on the optimalization of methods for the synthesis, isolation, and purification of 2-mercaptobenzothiazole-based acrylic and methacrylic monomers. The structures of the newly synthesized compounds were confirmed through infrared (IR) and nuclear magnetic resonance spectroscopy (NMR). Spectroscopic properties of the resulting 2-mercaptobenzothiazole derivatives were determined based on their absorption spectra and molar absorption coefficients in solvents with varying polarities. A correlation was established between the calculated density functional theory (DFT) energies and Frontier Molecular Orbitals and the experimental observations, confirming their consistency. The practical utility of the synthesized compounds, particularly in future polymerization processes, hinges on a thorough understanding of these properties. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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14 pages, 8151 KiB

Open AccessArticle

The Effect of Plasma Treatment on the Mechanical and Biological Properties of Polyurethane Artificial Blood Vessel

by Cheng Ding, Jing Ma, Yingxue Teng and Shanshan Chen

Materials 2023, 16(22), 7231; https://doi.org/10.3390/ma16227231 - 19 Nov 2023

Viewed by 685

Abstract

In recent years, the incidence of cardiovascular disease has increased annually, and the demand for artificial blood vessels has been increasing. Due to the formation of thrombosis and stenosis after implantation, the application of many materials in the human body has been inhibited. [...] Read more.

In recent years, the incidence of cardiovascular disease has increased annually, and the demand for artificial blood vessels has been increasing. Due to the formation of thrombosis and stenosis after implantation, the application of many materials in the human body has been inhibited. Therefore, the choice of surface modification process is very important. In this paper, small-diameter polyurethane artificial blood vessels were prepared through electrospinning, and their surfaces were treated with plasma to improve their biological properties. The samples before and after plasma treatment were characterized by SEM, contact angle, XPS, and tensile testing; meanwhile, the cell compatibility and blood compatibility were evaluated. The results show that there are no significant changes to the fiber morphology or diameter distribution on the surface of the sample before and after plasma treatment. Plasma treatment can increase the proportion of oxygen-containing functional groups on the surface of the sample and improve its wettability, thereby increasing the infiltration ability of cells and promoting cell proliferation. Plasma treatment can reduce the risk of hemolysis, and does not cause platelet adhesion. Due to the etching effect of plasma, the mechanical properties of the samples decreased with the extension of plasma treatment time, which should be used as a basis to balance the mechanical property and biological property of artificial blood vessels. But on the whole, plasma treatment has positive significance for improving the comprehensive performance of samples. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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17 pages, 31634 KiB

Open AccessArticle

In Situ Observation of Micro-Patterned Elastomeric Surfaces: The Formation of the Area of Real Contact and the Influence on Its Friction and Deformation Behaviour

by Andreas Hausberger, Marina Pecora, Damien Favier, Elisabeth Rossegger, Martin Tockner, Thomas Ules, Matthias Haselmann, Sandra Schlögl and Christian Gauthier

Materials 2023, 16(19), 6489; https://doi.org/10.3390/ma16196489 - 29 Sep 2023

Cited by 1 | Viewed by 930

Abstract

Structured surfaces, which are the basis of the lotus blossom effect, have great potential to serve/operate as functionalised surfaces, i.e., surfaces with specific and/or adjustable properties. In the present study, the aim is to use micro-structured elastomeric surfaces to specifically influence the friction [...] Read more.

Structured surfaces, which are the basis of the lotus blossom effect, have great potential to serve/operate as functionalised surfaces, i.e., surfaces with specific and/or adjustable properties. In the present study, the aim is to use micro-structured elastomeric surfaces to specifically influence the friction and deformation behaviours on the basis of the shape and arrangement of the structures. Thiol-acrylate-based photopolymers patterned via nanoimprint lithography were investigated by using an in situ tribological measurement set-up. A clear influence of the different structures on the surface’s friction behaviour could be shown, and, furthermore, this could be brought into relation with the real area of contact. This finding provides an important contribution to further development steps, namely, to give the structures switchable properties in order to enable the control of friction properties in a targeted manner. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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15 pages, 6115 KiB

Open AccessArticle

Critical Evaluation of the Methods for the Characterization of the Degree of Sulfonation for Electron Beam Irradiated and Non-Irradiated Sulfonated Poly(ether ether ketone) Membranes

by Laura Dace Pakalniete, Elizabete Maskova, Rudolfs Janis Zabolockis, Liga Avotina, Einars Sprugis, Ingars Reinholds, Magdalena Rzepna, Guntars Vaivars and Elina Pajuste

Materials 2023, 16(18), 6098; https://doi.org/10.3390/ma16186098 - 06 Sep 2023

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Abstract

Sulfonated poly(ether ether ketone) (SPEEK) materials are promising candidates for replacing Nafion™ in applications such as proton exchange membrane (PEM) and direct methanol fuel cells. SPEEK membranes have several advantages such as low cost, thermal and radiation stability and controllable physicochemical and mechanical [...] Read more.

Sulfonated poly(ether ether ketone) (SPEEK) materials are promising candidates for replacing Nafion™ in applications such as proton exchange membrane (PEM) and direct methanol fuel cells. SPEEK membranes have several advantages such as low cost, thermal and radiation stability and controllable physicochemical and mechanical properties, which depend on the degree of sulfonation (DS). Commercial PEEK was homogenously sulfonated up to a DS of 60–90% and the membranes were prepared using a solvent casting method. Part of the samples were irradiated with a 10 MeV electron beam up to a 500 kGy dose to assess the ionizing radiation-induced effects. Both non-irradiated and irradiated membranes were characterized by Fourier Transformation infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), proton nuclear magnetic resonance (¹H-NMR) spectroscopy, electrochemical impedance analysis and, for the first time for non-irradiated membranes, by spectrophotometric analysis with Cr(III). The above-mentioned methods for application for DS assessment were compared. The aim of this study is to compare different methods used for the determination of the DS of SPEEK membranes before and after high-dose irradiation. It was observed that irradiated membranes presented a higher value of DS. The appearance of different new signals in ¹H-NMR and FT-IR spectra of irradiated membranes indicated that the effects of radiation induced changes in the structure of SPEEK materials. The good correlation of Cr(III) absorption and SPEEK DS up to 80% indicates that the spectrophotometric method is a comparable tool for the characterization of SPEEK membranes. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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10 pages, 1302 KiB

Open AccessArticle

Polysaccharide Composite Films Utilising Wood Waste

by Anita Kwaśniewska, Michał Świetlicki, Beata Kowalska and Grzegorz Gładyszewski

Materials 2023, 16(17), 6031; https://doi.org/10.3390/ma16176031 - 02 Sep 2023

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Abstract

This study aimed to investigate the effect of raw waste pine wood dust (Pinus sylvestris) from furniture production on polysaccharide biopolymer film properties. The obtained biocomposite films produced via the casting method were prepared with 20% glycerol and 0%, 5%, 10%, [...] Read more.

This study aimed to investigate the effect of raw waste pine wood dust (Pinus sylvestris) from furniture production on polysaccharide biopolymer film properties. The obtained biocomposite films produced via the casting method were prepared with 20% glycerol and 0%, 5%, 10%, 15%, 20%, and 25% of added wood dust in relation to the dry starch matter. Wood dust composition and particle size distribution analysis were performed. In order to evaluate the material surface properties, tests were carried out using an atomic force microscope (AFM) and a contact angle goniometer. Utilising uniaxial tensile test methodology, the values for both tensile strength and Young’s modulus were determined. In addition, the barrier properties, water solubility index, and colour were also investigated. The research showed that wood dust affected the functional parameters of the obtained biocomposites. A wood dust content increase causes the Young’s modulus value to rise with a progressive decrease in the max. strain. The filler did not change the films’ wetting properties, and each had a hydrophilic surface regardless of the additive amount. The bio-sourced composites obtained were non-toxic and environmentally neutral materials, suitable to be applied in the packaging industry as well as the agriculture sector. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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17 pages, 5426 KiB

Open AccessArticle

Novel Bio-Based Materials: From Castor Oil to Epoxy Resins for Engineering Applications

by Constantin Gaina, Oana Ursache, Viorica Gaina, Alexandru-Mihail Serban and Mihai Asandulesa

Materials 2023, 16(16), 5649; https://doi.org/10.3390/ma16165649 - 16 Aug 2023

Cited by 1 | Viewed by 908

Abstract

The paper presents the synthesis and thermal behavior of novel epoxy resins prepared from epoxidized castor oil in the presence of or without trimethylolpropane triglycidyl ether (TMP) crosslinked with 3-hexahydro-4-methylphtalic anhydride (MHHPA) and their comparison with a petroleum-based epoxy resin (MHHPA and TMP). [...] Read more.

The paper presents the synthesis and thermal behavior of novel epoxy resins prepared from epoxidized castor oil in the presence of or without trimethylolpropane triglycidyl ether (TMP) crosslinked with 3-hexahydro-4-methylphtalic anhydride (MHHPA) and their comparison with a petroleum-based epoxy resin (MHHPA and TMP). Epoxidized castor oil (ECO) was obtained via in situ epoxidation of castor oil with peroxyacetic acid. The chemical structures of castor oil (CO), ECO, and epoxy matrix were confirmed using FT-IR and ¹H-NMR spectroscopy. The morphological and thermal behavior of the resulting products have been investigated. Compared to petroleum-based resins, castor oil-based ones have a lower T_g. Anyway, the introduction of TMP increases the T_g of the resins containing ECO. The morphological behavior is not significantly influenced by using ECO or by adding TMP in the synthesis of resins. The dielectric properties of epoxy resins have been analyzed as a function of frequency (1 kHz–1 MHz) and temperature (−50 to 200 °C). The water absorption test showed that as T_g increased, the percent mass of water ingress decreased. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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Review

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35 pages, 33012 KiB

Open AccessEditor’s ChoiceReview

Dynamic Hydrogels with Viscoelasticity and Tunable Stiffness for the Regulation of Cell Behavior and Fate

by Yuhang Zhang, Zhuofan Wang, Qingqing Sun, Qian Li, Shaohui Li and Xiaomeng Li

Materials 2023, 16(14), 5161; https://doi.org/10.3390/ma16145161 - 21 Jul 2023

Cited by 6 | Viewed by 2155

Abstract

The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and [...] Read more.

The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and dynamic stiffness have recently been used to investigate the regulation of cell behavior and fate. This article first emphasizes the importance of tissue viscoelasticity and dynamic stiffness and provides an overview of characterization techniques at both macro- and microscale. Then, the viscoelastic hydrogels (crosslinked via ion bonding, hydrogen bonding, hydrophobic interactions, and supramolecular interactions) and dynamic stiffness hydrogels (softening, stiffening, and reversible stiffness) with different crosslinking strategies are summarized, along with the significant impact of viscoelasticity and dynamic stiffness on cell spreading, proliferation, migration, and differentiation in two-dimensional (2D) and three-dimensional (3D) cell cultures. Finally, the emerging trends in the development of dynamic mechanical hydrogels are discussed. Full article

(This article belongs to the Special Issue Feature Paper in the Section 'Polymeric Materials' (2nd Edition))

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