Polymers

14 pages, 7118 KB

Open AccessArticle

Enhancing Antibacterial Dental Matrices: Balancing Antibacterial Activity and Mechanical Properties Through Quaternary Ammonium UDMA Analogues

by Marta Chrószcz-Porębska, Alicja Kazek-Kęsik, Izabella Ślęzak-Prochazka, Grzegorz Chladek and Izabela Maria Barszczewska-Rybarek

Polymers 2026, 18(3), 426; https://doi.org/10.3390/polym18030426 - 6 Feb 2026

Viewed by 465

Abstract

The research hypothesis was that adjusting the content of the quaternary ammonium urethane dimethacrylate monomer bearing an N-dodecyl substituent (QAUDMA-12) would yield dental matrices with high antimicrobial activity, good biocompatibility, and favorable physicochemical properties. The research hypothesis was verified for six Bis-GMA, TEGDMA, [...] Read more.

The research hypothesis was that adjusting the content of the quaternary ammonium urethane dimethacrylate monomer bearing an N-dodecyl substituent (QAUDMA-12) would yield dental matrices with high antimicrobial activity, good biocompatibility, and favorable physicochemical properties. The research hypothesis was verified for six Bis-GMA, TEGDMA, and UDMA copolymers containing from 2.5 to 40 wt.% QAUDMA-12 by determining their degree of conversion, hardness, flexural properties, water behavior, antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Candida albicans, and cytotoxicity towards L929 mouse fibroblast cells. The research hypothesis was confirmed. Copolymers containing less than 30 wt.% QAUDMA-12 exhibited favorable polymerization efficiency, water sorption and solubility, and mechanical properties comparable to those of conventional Bis-GMA/TEGDMA systems. At the same time, they showed no cytotoxic effects toward mouse fibroblast cells. The results of antimicrobial tests show that the minimum QAUDMA-12 concentration providing sufficient antimicrobial activity was 20 wt.%. Therefore, it can be concluded that the 20 wt.% concentration of QAUDMA-12 makes it possible to obtain dental matrices that are non-toxic, exhibit antimicrobial activity, and possess the desired physico-mechanical performance. Full article

(This article belongs to the Special Issue Polymeric Biomaterials for Dental Regeneration and Antimicrobial Applications)

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16 pages, 2643 KB

Open AccessEditor’s ChoiceArticle

Hydrophobic Fibers with Hydrophilic Domains for Enhanced Fog Water Harvesting

by Joanna Knapczyk-Korczak, Katarzyna Marszalik, Marcin Gajek and Urszula Stachewicz

Polymers 2026, 18(3), 425; https://doi.org/10.3390/polym18030425 - 6 Feb 2026

Viewed by 708

Abstract

Fog water collectors (FWCs) present a sustainable solution for arid regions where fog is a primary water source. To improve their efficiency, we developed a durable and high-performance mesh composed of electrospun hydrophobic thermoplastic polyurethane (TPU) fibers combined with hydrophilic cellulose acetate (CA) [...] Read more.

Fog water collectors (FWCs) present a sustainable solution for arid regions where fog is a primary water source. To improve their efficiency, we developed a durable and high-performance mesh composed of electrospun hydrophobic thermoplastic polyurethane (TPU) fibers combined with hydrophilic cellulose acetate (CA) microbeads. This hybrid design represents a novel biomimetic strategy, mimicking natural fog-harvesting mechanisms by optimizing wetting and drainage. Despite the significant reduction in average fiber diameter, the TPU-CA mesh maintained mechanical strength close to 1 MPa, comparable to pristine TPU. The introduction of hydrophilic domains into a hydrophobic fibrous network is a unique architectural approach that enhanced fog collection performance, achieving a high water harvesting rate of 127 ± 12 mg·cm⁻²·h⁻¹. Remarkably, although the mesh remained predominantly hydrophobic, droplets shed completely from its vertical surface, exhibiting near-zero contact angle hysteresis. This synergistic wetting concept enables performance unattainable with conventional single-wettability meshes. Compared to single-material meshes, the TPU-CA hybrid showed nearly double the water collection efficiency. The innovative interplay between surface chemistry, microscale heterogeneity, and mechanical robustness is key to maximizing water capture and transport, offering a promising path for scalable, efficient FWCs in poor water-stressed regions. Full article

(This article belongs to the Special Issue Synthesis, Production and Applications of Cellulose)

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15 pages, 17390 KB

Open AccessArticle

Development of Sustainable Red Algae–Sisal Fiber Composite Films via Doctor Blading

by Matthew Richards, Joshua Baird, Noah Serda, Vuong Do and Yanika Schneider

Polymers 2026, 18(3), 424; https://doi.org/10.3390/polym18030424 - 6 Feb 2026

Viewed by 487

Abstract

This study investigated the properties of red algae (RA) biocomposite films reinforced with natural sisal fibers and plasticized with glycerol. The polymer was extracted from locally sourced red seaweed and combined sisal fibers at varying fiber loadings (0–45 wt%) using the doctor blading [...] Read more.

This study investigated the properties of red algae (RA) biocomposite films reinforced with natural sisal fibers and plasticized with glycerol. The polymer was extracted from locally sourced red seaweed and combined sisal fibers at varying fiber loadings (0–45 wt%) using the doctor blading technique. Composite films were analyzed using a variety of methods to evaluate the chemical composition, thermal behavior and mechanical performance. Infrared spectroscopy confirmed the presence of kappa-carrageenan as the dominant polysaccharide in the RA matrix, whereas elemental analysis verified the dilution of sulfur content and enrichment of carbon with increasing fiber incorporation. Thermal stability increased with fiber loading, peaking at 30 wt% sisal fiber before decreasing slightly at 45 wt% due to poor fiber dispersion. Mechanical testing demonstrated an optimal balance between strength and flexibility at 30 wt% sisal fiber, with a 37% increase in strength compared to the pure RA film. Overall, the findings demonstrate that sisal fiber reinforcement enhances the structural integrity and stability of RA-based films, supporting their potential as biodegradable alternatives to petroleum-based plastics. Full article

(This article belongs to the Special Issue Development in Fiber-Reinforced Polymer Composites: 2nd Edition)

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20 pages, 4719 KB

Open AccessArticle

Optimizing Mechanical and Thermal Properties of Slag-Based Geopolymer Fiber Boards via Fiber Pretreatment and Reinforcement Type

by Sebnem Sevil Arpaci and Ergun Guntekin

Polymers 2026, 18(3), 423; https://doi.org/10.3390/polym18030423 - 6 Feb 2026

Cited by 1 | Viewed by 884

Abstract

This study aims to optimize the physical, mechanical, and thermal properties of 100% Ground Granulated Blast Furnace Slag (GGBFS) based geopolymer wood-composite panels. Pine fibers were utilized as the primary reinforcement matrix, while glass and hemp fibers were introduced as secondary reinforcements at [...] Read more.

This study aims to optimize the physical, mechanical, and thermal properties of 100% Ground Granulated Blast Furnace Slag (GGBFS) based geopolymer wood-composite panels. Pine fibers were utilized as the primary reinforcement matrix, while glass and hemp fibers were introduced as secondary reinforcements at varying proportions (3%, 6%, 9% by weight). The research investigated the effects of fiber pretreatments (hot water vs. 1% NaOH) and reinforcement hybridization. Results indicate that GGBFS successfully geopolymerized, forming a hybrid N-A-S-H and C-A-S-H gel network. Quantitative analysis revealed that 9% glass fiber reinforcement yielded the highest mechanical performance, achieving a Modulus of Rupture (MOR) of 10.05 N/mm² and Internal Bond (IB) strength of 1.32 N/mm², alongside superior water resistance (1.0% Thickness Swelling). Conversely, while hemp fiber inclusion reduced mechanical strength (MOR: 5.77 N/mm² at 9%), it significantly enhanced thermal insulation, reducing thermal conductivity to 0.10 W/m·K. It was observed that aggressive NaOH pretreatment caused alkali-induced degradation of pine fibers, negatively impacting the composite’s integrity compared to hot water treatment. This study demonstrates the feasibility of tailoring 100% slag-based geopolymer composites for either structural (glass-reinforced) or insulating (hemp-reinforced) applications using industrial by-products. Full article

(This article belongs to the Section Polymer Fibers)

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24 pages, 7198 KB

Open AccessArticle

Toward Sustainable Printed Packaging: Surface Properties and Ink Adhesion Behavior of PLA/PCL/Nanosilica Biopolymer Blends

by Sanja Mahović Poljaček, Tamara Tomašegović and Dino Priselac

Polymers 2026, 18(3), 422; https://doi.org/10.3390/polym18030422 - 6 Feb 2026

Viewed by 542

Abstract

In this study, polylactic acid (PLA) was blended with poly(ε-caprolactone) (PCL) and reinforced with nanosilica (SiO₂) to tailor surface characteristics and improve adhesion in biopolymer-based printed packaging applications. The surface microstructure and topography were analyzed using FTIR-ATR, SEM, and surface profilometry. [...] Read more.

In this study, polylactic acid (PLA) was blended with poly(ε-caprolactone) (PCL) and reinforced with nanosilica (SiO₂) to tailor surface characteristics and improve adhesion in biopolymer-based printed packaging applications. The surface microstructure and topography were analyzed using FTIR-ATR, SEM, and surface profilometry. Surface wettability and surface free energy (SFE), along with the adhesion properties of printed ink layers on polymer blends, were assessed, and the optical properties of the substrates and prints were evaluated. SEM revealed that PLA/PCL blends exhibited phase-separated morphologies with PCL droplet domains, whereas incorporation of 3 wt% SiO₂ resulted in finer dispersion and reduced surface irregularities. Surface roughness (Ra) increased from 1.92 µm for PLA/SiO₂ 100/3 to 4.45 µm for PLA/PCL/SiO2 50/50/0, while water contact angle decreased from 70.9° for neat PLA to 43.4° for PLA/SiO₂ 100/3 surface, reflecting enhanced hydrophilicity. SFE components ranged from 26 to 40.7 mJ/m² (dispersive) and 3.2 to 21.5 mJ/m² (polar). Adhesion parameters (interfacial tension ranging from 0.01 to 5.54 mJ/m², work of adhesion from 76.9 to 97.3 mJ/m², and wetting coefficient from 3.04 to 11.1 mJ/m²) indicated favorable ink compatibility for most blends, and optical density of the printed layers (1.85–2.35) confirmed potential for good printability. These findings demonstrate that PLA/PCL/SiO₂ blends allow controlled tuning of surface morphology, wettability, and adhesion, providing a promising approach for biodegradable and print-ready packaging substrates. Full article

(This article belongs to the Special Issue Recent Advances in Biobased and Biodegradable Polymer Materials for Packaging Applications)

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17 pages, 1807 KB

Open AccessArticle

Planar ICP Assisted One-Step Synthesis of pH-Responsive PDEAEMA Polymer Thin Films

by Zahide Tosun

Polymers 2026, 18(3), 421; https://doi.org/10.3390/polym18030421 - 6 Feb 2026

Viewed by 481

Abstract

Smart polymers have attracted significant scientific interest in recent years because of their capability to modify their physical and/or chemical properties in response to external stimuli, including temperature, pH, and electric or magnetic fields. Poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) is a pH-responsive polymer with significant [...] Read more.

Smart polymers have attracted significant scientific interest in recent years because of their capability to modify their physical and/or chemical properties in response to external stimuli, including temperature, pH, and electric or magnetic fields. Poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) is a pH-responsive polymer with significant potential for biomedical applications. Significant research has focused on the synthesis of PDEAEMA polymers given their potential in smart polymer applications. In this study, PDEAEMA thin films were synthesized via a planar inductively coupled plasma (ICP) system at 13.56 MHz in both continuous and pulsed modes. The effects of substrate temperature, plasma power, and plasma pulse off time on polymer surfaces were systematically studied. The deposited polymer films were analyzed for their chemical composition and structural properties using X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR). Additionally, the plasma environment was analyzed using Optical Emission Spectroscopy (OES). Results indicated that polymers prepared under pulsed plasma conditions more closely retained the structure of the monomer. Moreover, the deposition rate increased as the plasma pulse off time decreased in pulsed mode experiments. PDEAEMA-based copolymer films were deposited to investigate their behavior under different pH conditions. The results indicate that the films exhibited distinct responses in acidic and basic environments. Full article

(This article belongs to the Special Issue Functional Polymer Films for Surface Modification and Coating Applications)

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33 pages, 7817 KB

Open AccessArticle

Compressive Response and Energy Absorption of Additively Manufactured Elastomers with Varied Simple Cubic Architectures

by Lindsey B. Bezek, Sushan Nakarmi, Jeffery A. Leiding, Nitin P. Daphalapurkar, Santosh Adhikari and Kwan-Soo Lee

Polymers 2026, 18(3), 420; https://doi.org/10.3390/polym18030420 - 5 Feb 2026

Viewed by 553

Abstract

Additive manufacturing, and particularly the vat photopolymerization process, enables the fabrication of complex geometries at high resolution and small length scales, making it well-suited for fabricating cellular structures (e.g., foams and lattices). Among these, elastomeric cellular structures are of growing interest due to [...] Read more.

Additive manufacturing, and particularly the vat photopolymerization process, enables the fabrication of complex geometries at high resolution and small length scales, making it well-suited for fabricating cellular structures (e.g., foams and lattices). Among these, elastomeric cellular structures are of growing interest due to their tunable compliance and energy dissipation. However, comprehensive data on the compressive behavior of these structures remains limited, especially for investigating the structure-property effects from changing the density and distribution of material within the cellular structure. This study explores how the mechanical response of polyurethane-based simple cubic structures changes when varying volume fraction, unit cell length, and unit cell patterning, which have not been systematically investigated previously in additively manufactured elastomers. Increasing volume fraction from 10% to 50% yielded significant changes in compressive stress–strain performance (decreasing strain at 0.5 MPa by 41.6% and increasing energy absorption density by 3962.5%). Although changing the unit cell length between 2.5 and 7 mm in ~30 mm parts did not result in statistically different stress–strain responses, modifying the configuration of struts of different thicknesses across designs with 30% volume fraction altered the stress–strain behavior (differences of 12.5% in strain at 0.5 MPa and 109.4% for energy absorption density). Power law relationships were developed to understand the interactions between volume fraction, unit cell length, and elastic modulus, and experimental data showed strong fits (R² > 0.91). These findings enhance the understanding of how multiple structural design aspects influence the performance of elastomeric cellular materials, providing a foundation for informing strategic design of tailorable materials for diverse mechanical applications. Full article

(This article belongs to the Special Issue Additive Manufacturing Technology of Polymer-Based Composites)

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13 pages, 2707 KB

Open AccessArticle

An Investigation of the Electrical Performance of Polymer-Based Stretchable TFTs Under Mechanical Strain Using the Y-Function Method

by Hyunjong Lee, Hyunbum Kang, Chanho Jeong, Insung Choi, Sohee Kim, Eunki Baek, JongKwon Lee, Dongwook Kim, Jaehoon Park, Gae Hwang Lee and Youngjun Yun

Polymers 2026, 18(3), 419; https://doi.org/10.3390/polym18030419 - 5 Feb 2026

Viewed by 507

Abstract

Stretchable semiconductors capable of maintaining electrical performance under large mechanical deformation are essential for reliable wearable electronic devices. However, polymer semiconductors often suffer from electrical degradation when subjected to tensile strain. In this study, electrical stability under strain was achieved by using a [...] Read more.

Stretchable semiconductors capable of maintaining electrical performance under large mechanical deformation are essential for reliable wearable electronic devices. However, polymer semiconductors often suffer from electrical degradation when subjected to tensile strain. In this study, electrical stability under strain was achieved by using a rubber-blended poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)diketopyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophene) (DPPT-TT) polymer semiconductor based on a conjugated polymer/elastomer phase separation-induced elasticity (CONPHINE) structure. Unlike most previous studies on fully stretchable thin-film transistors (TFTs), which primarily report overall performance changes under mechanical strain, this work systematically identifies the dominant origin of electrical performance degradation through a stepwise electrical analysis encompassing the gate insulating layer, the semiconductor layer, and complete devices. Bottom-gate top-contact (BGTC) and bottom-gate bottom-contact (BGBC) devices were fabricated on rigid Si/SiO₂ substrates to examine the intrinsic properties of the DPPT-TT/styrene-ethylene-butylene-styrene (SEBS) CONPHINE film. As a result, the device exhibits 90% mobility retention even at 100% tensile strain applied parallel to the charge transport direction. Quantitative resistance analysis using the Y-function method reveals that variations in channel resistance play a dominant role in strain-induced performance degradation, whereas changes in contact resistance contribute only marginally. These findings demonstrate that stabilizing channel resistance, rather than contact resistance, is important for achieving high mobility retention under large mechanical deformation, thereby providing concrete and quantitative design guidelines for reliable stretchable TFTs. Full article

(This article belongs to the Special Issue Application and Development of Polymeric Materials in Electrochemistry)

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23 pages, 2936 KB

Open AccessArticle

Performance of a High-Molecular-Weight AM/AA Copolymer in a CO₂–Water Polymer Hybrid Fracturing Fluid Under High-Temperature and High-Pressure Conditions

by Tengfei Chen, Shutao Zhou, Tingwei Yao, Meilong Fu, Zhigang Wen and Quanhuai Shen

Polymers 2026, 18(3), 418; https://doi.org/10.3390/polym18030418 - 5 Feb 2026

Viewed by 487

Abstract

To reduce water consumption and potential formation damage associated with conventional water-based fracturing fluids while improving the proppant-carrying and flow adaptability of CO₂-based systems without relying on specialized CO₂ thickeners, a CO₂–water polymer hybrid fracturing fluid was developed [...] Read more.

To reduce water consumption and potential formation damage associated with conventional water-based fracturing fluids while improving the proppant-carrying and flow adaptability of CO₂-based systems without relying on specialized CO₂ thickeners, a CO₂–water polymer hybrid fracturing fluid was developed using an AM/AA copolymer (poly(acrylamide-co-acrylic acid), P(AM-co-AA)) as the thickening agent for the aqueous phase. Systematic experimental investigations were conducted under high-temperature and high-pressure conditions. Fluid-loss tests at different CO₂ volume fractions show that the CO₂–water polymer hybrid fracturing fluid system achieves a favorable balance between low fluid loss and structural continuity within the range of 30–50% CO₂, with the most stable fluid-loss behavior observed at 40% CO₂. Based on this ratio window, static proppant-carrying experiments indicate controllable settling behavior over a temperature range of 20–80 °C, leading to the selection of 60% polymer-based aqueous phase + 40% CO₂ as the optimal mixing ratio. Rheological results demonstrate pronounced shear-thinning behavior across a wide thermo-pressure range, with viscosity decreasing systematically with increasing shear rate and temperature while maintaining continuous and reproducible flow responses. Pipe-flow tests further reveal that flow resistance decreases monotonically with increasing flow velocity and temperature, indicating stable transport characteristics. Phase visualization observations show that the CO₂–water polymer hybrid fracturing fluid system exhibits a uniform milky dispersed appearance under moderate temperature or elevated pressure, whereas bubble-dominated structures and spatial phase separation gradually emerge under high-temperature and relatively low-pressure static conditions, highlighting the sensitivity of phase stability to thermo-pressure conditions. True triaxial hydraulic fracturing experiments confirm that the CO₂–water polymer hybrid fracturing fluid enables stable fracture initiation and sustained propagation under complex stress conditions. Overall, the results demonstrate that the AM/AA copolymer-based aqueous phase can provide effective viscosity support, proppant-carrying capacity, and flow adaptability for CO₂–water polymer hybrid fracturing fluid over a wide thermo-pressure range, confirming the feasibility of this approach without the use of specialized CO₂ thickeners. Full article

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

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24 pages, 2226 KB

Open AccessArticle

Biopolymeric Films and Coatings Based on Purple Corn Flour and Propolis: Physicochemical Properties and Application in the Preservation of Fuerte Avocado

by Ronald Díaz-Saenz, Dagnith L. Bejarano-Luján, Franklin Lozano and Luis R. Paredes-Quiroz

Polymers 2026, 18(3), 417; https://doi.org/10.3390/polym18030417 - 5 Feb 2026

Viewed by 792

Abstract

Natural preservation technologies have emerged as sustainable alternatives for maintaining the postharvest quality of fresh products. This study developed and characterized edible films and coatings produced from purple corn flour (MMH) and ethanolic propolis extract (EEP), and evaluated their effectiveness in extending the [...] Read more.

Natural preservation technologies have emerged as sustainable alternatives for maintaining the postharvest quality of fresh products. This study developed and characterized edible films and coatings produced from purple corn flour (MMH) and ethanolic propolis extract (EEP), and evaluated their effectiveness in extending the shelf life of Fuerte avocado. Film-forming solutions were prepared using three MMH/EEP formulations (100/0, 90/10, and 80/20), and their apparent viscosity was determined. Films obtained by drying at 45 °C for 12 h were analyzed for pH, thickness, tensile strength, solubility, water vapor permeability, and microstructure by SEM. The MMH 80/20 EEP formulation showed the best overall performance and was selected as a coating for avocados stored under ambient and refrigerated conditions. Shelf life was defined based on quantitative criteria, including acceptable limits of weight loss and sensory acceptability. Under these criteria, coated avocados reached a shelf life of 30 days at ambient temperature, compared to 15 days for uncoated fruit, and 72 days under refrigerated storage, compared to 50 days for the control. Additionally, the coating reduced weight loss, preserved moisture, and improved sensory acceptance. Overall, MMH/EEP systems represent a promising natural alternative for the postharvest preservation of avocado. Full article

(This article belongs to the Section Polymer Membranes and Films)

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18 pages, 1694 KB

Open AccessArticle

Effects of Repeated Thermo-Mechanical Processing on the Degradation Behavior of Bottle-Grade PET Under Controlled Conditions

by Mária Straková, Slávka Hlaváčiková, Jozef Feranc, Henrieta Suchánková, Zuzana Kramárová, Michal Ďurfina, Leona Omaníková, Mohammadhassan Rahnama Hezaveh, Katarína Tomanová, Zuzana Vanovčanová, Ján Kruželák, Pavol Alexy and Roderik Plavec

Polymers 2026, 18(3), 416; https://doi.org/10.3390/polym18030416 - 5 Feb 2026

Viewed by 769

Abstract

Mechanical recycling of polyethylene terephthalate (PET) is a key strategy for circular packaging applications; however, repeated thermo-mechanical processing leads to progressive polymer degradation. In this study, the effect of controlled repeated extrusion on the degradation behavior of bottle-grade PET was systematically investigated under [...] Read more.

Mechanical recycling of polyethylene terephthalate (PET) is a key strategy for circular packaging applications; however, repeated thermo-mechanical processing leads to progressive polymer degradation. In this study, the effect of controlled repeated extrusion on the degradation behavior of bottle-grade PET was systematically investigated under laboratory conditions. Mechanical recycling was simulated using a co-rotating twin-screw extruder, where PET was subjected to up to four consecutive processing cycles corresponding to a cumulative residence time of 8 min. Progressive processing resulted in chain scission, reflected by a decrease in intrinsic viscosity from approximately 0.80 to 0.65 dL·g⁻¹ and a corresponding reduction in molecular weight. Melt flow rate increased accordingly, indicating a gradual loss of melt strength. Differential scanning calorimetry revealed that the glass transition and melting temperatures remained nearly unchanged, while the degree of crystallinity increased from approximately 23.0% to 29.5%, accompanied by changes in crystallization behavior. These structural changes led to reduced ductility, with elongation at break decreasing from about 84% to 60%. Optical analysis showed systematic material darkening, and a strong linear correlation between lightness (L*) and intrinsic viscosity was observed. By isolating intrinsic thermo-mechanical degradation effects under controlled processing conditions, this study enables a clearer definition of realistic reuse limits for mechanically recycled bottle-grade PET. The results indicate that bottle-grade PET retains properties compatible with demanding applications only after a limited number of thermo-mechanical processing cycles, whereas further processing restricts its usability to less demanding applications such as fibers, films, and non-food packaging. Full article

(This article belongs to the Special Issue Advances in Recycling and Reuse of Polymers)

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24 pages, 4242 KB

Open AccessArticle

A Flexible, Antibacterial Platform: Silver-Tuned Polyvinyl Alcohol with Enhanced Opto-Mechanical and Electrical Properties

by Abdelazim M. Mebed, Ali H. Mohsen, Diyar J. Hassan, Nadia A. Ali, Seenaa I. Hussein, Farah T. M. Noori, Alaa M. Abd-Elnaiem, Alhafez M. Alraih and Randa F. Abdelbaki

Polymers 2026, 18(3), 415; https://doi.org/10.3390/polym18030415 - 5 Feb 2026

Viewed by 684

Abstract

Silver/polyvinyl alcohol (Ag/PVA) nanocomposite films were synthesized via solution casting with varying concentrations of Ag nanoparticles (1–5 wt%). A comprehensive investigation was conducted to understand the influence of Ag content on the structural, optical, mechanical, thermal, electrical, and antibacterial properties of the composites. [...] Read more.

Silver/polyvinyl alcohol (Ag/PVA) nanocomposite films were synthesized via solution casting with varying concentrations of Ag nanoparticles (1–5 wt%). A comprehensive investigation was conducted to understand the influence of Ag content on the structural, optical, mechanical, thermal, electrical, and antibacterial properties of the composites. UV-Vis spectroscopy revealed a red shift in absorption peaks and a reduction in the optical band gap, which decreased from 3.78 eV for pure PVA to 3.37 eV for the 5 wt% Ag composite. FTIR and SEM analyses confirmed successful nanoparticle incorporation and morphological changes. The nanocomposites exhibited enhanced tensile strength, elongation at break, Young’s modulus, and hardness due to strong interfacial interactions. The addition of Ag also increased hydrophobicity and imparted effective antibacterial activity. The electrical and thermal properties showed significant improvement: AC conductivity increased from 5.8 × 10⁻⁹ to 1.01 × 10⁻⁴ S/cm with Ag content, while the dielectric constant decreased. A high DC conductivity of 1.5 × 10⁵ S/cm was achieved with only 3 wt% Ag. Thermal conductivity also rose from 0.27 W/m·K for pure PVA to 0.92 W/m·K for the 5 wt% composite. These results demonstrate that Ag/PVA nanocomposites are promising multifunctional materials for flexible electronics, combining tunable optoelectronic properties with enhanced mechanical, thermal, and antibacterial performance. Full article

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

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15 pages, 2723 KB

Open AccessArticle

Effect of Charge Distribution Along Anionic Polyacrylamide Chains on Quartz Adsorption: A Molecular Dynamics Study

by Gonzalo R. Quezada, Karien I. García, Enoque Diniz Mathe, Williams Leiva, Eder Piceros, Pedro Robles and Ricardo I. Jeldres

Polymers 2026, 18(3), 414; https://doi.org/10.3390/polym18030414 - 5 Feb 2026

Viewed by 489

Abstract

The interfacial behavior of polyelectrolytic flocculants is governed not only by their chemical composition but also by the molecular-scale distribution of charged and neutral segments, which directly influences transport, adsorption, and interfacial stability. In this work, classical molecular dynamics simulations are used to [...] Read more.

The interfacial behavior of polyelectrolytic flocculants is governed not only by their chemical composition but also by the molecular-scale distribution of charged and neutral segments, which directly influences transport, adsorption, and interfacial stability. In this work, classical molecular dynamics simulations are used to elucidate how charge-site architecture controls the conformation, dynamics, and adsorption stability of anionic polyacrylamides at the quartz–water interface. Polymer architectures ranging from homogeneous charge distributions to block-like arrangements were systematically analyzed at constant molecular weight and global charge density. The results show that increasing charge segregation induces more compact conformations, enhanced translational mobility in solution, and reduced solvent accessibility. At the interface, polymers containing extended neutral blocks exhibit significantly more stable adsorption on quartz than polymers with homogeneously distributed charges, consistent with the low surface charge density of silica. These findings demonstrate that charge-site distribution is an independent and critical design parameter governing polymer–surface interactions. From a chemical engineering perspective, the results provide fundamental insight relevant to the rational design of polymeric additives for solid–liquid separation, flocculation, and sustainable mineral processing applications. Full article

(This article belongs to the Special Issue Advances in Block Copolymers: Synthesis, Characterization and Applications)

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21 pages, 5555 KB

Open AccessArticle

Structural and Functional Modifications of Hazelnut Proteins Induced by Atmospheric Cold Plasma

by Suzan Uzun

Polymers 2026, 18(3), 413; https://doi.org/10.3390/polym18030413 - 5 Feb 2026

Cited by 1 | Viewed by 492

Abstract

This study evaluated the effects of atmospheric cold plasma (ACP) treatment duration on the physicochemical and functional properties of hazelnut protein. Proteins were extracted from defatted hazelnut flour and subjected to ACP for 0, 2, 4, 6, and 8 min. The results demonstrated [...] Read more.

This study evaluated the effects of atmospheric cold plasma (ACP) treatment duration on the physicochemical and functional properties of hazelnut protein. Proteins were extracted from defatted hazelnut flour and subjected to ACP for 0, 2, 4, 6, and 8 min. The results demonstrated that ACP treatment significantly modified protein characteristics: it generally reduced particle size and increased absolute zeta potential, with the smallest particles observed after 4 and 6 min of treatment. Concurrently, a decrease in L, a, and b color values indicated sample darkening with extended processing. Structural analysis revealed that ACP induced changes in protein secondary structure, leading to a significant increase in surface hydrophobicity and a decrease in free sulfhydryl content. These structural and physicochemical modifications, particularly the enhanced surface hydrophobicity and reduced particle size, collectively improved emulsifying activity and stability, as well as foaming capacity and stability. The highest emulsion and foaming stability were observed in samples treated for 6 min. Hazelnut protein gels exhibited pronounced solid-like behavior and ACP treatment enhanced the rheological properties of the gels, with the maximum gel strength observed at a 6 min treatment. Overall, these findings indicate that ACP is an effective non-thermal technology for positively altering the physicochemical and techno-functional properties of hazelnut protein. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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15 pages, 3236 KB

Open AccessArticle

Silk Fibroin Hydrogel Microneedles Loaded with Recombinant Human Nerve Growth Factor for Corneal Tissue Engineering

by Jinmei Zhang, Linran Song, Xinrang Zhai, Dilnaz Em and Xihao Pan

Polymers 2026, 18(3), 412; https://doi.org/10.3390/polym18030412 - 5 Feb 2026

Viewed by 862

Abstract

Corneal nerves are essential for maintaining the functional integrity of the ocular surface. Damage to corneal nerves can lead to corneal issues and impaired vision. Current treatments for corneal nerve damage are inadequate, thus highlighting the need for innovative therapeutic approaches. In this [...] Read more.

Corneal nerves are essential for maintaining the functional integrity of the ocular surface. Damage to corneal nerves can lead to corneal issues and impaired vision. Current treatments for corneal nerve damage are inadequate, thus highlighting the need for innovative therapeutic approaches. In this study, we present a hydrogel microneedle system designed to facilitate the sustained release of recombinant human nerve growth factor (rhNGF). The microneedle features a tip composed of glycidyl methacrylate modified silk fibroin (SFMA) loaded with rhNGF, photopolymerized for structural integrity, while its base is formed using silk fibroin (SF). This design allows the microneedles to penetrate the corneal epithelium and deliver rhNGF to the sub-epithelial layer. The crosslinking process not only provides the mechanical strength required for microneedle penetration but also enables sustained drug release. The proposed rhNGF-loaded SF hydrogel microneedle provides a platform for drug delivery, serving as a novel therapeutic option for corneal tissue engineering. Full article

(This article belongs to the Special Issue Advanced Polymers for Biomedical Applications: Preparation and Application)

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21 pages, 21342 KB

Open AccessArticle

Dynamic Buckling Analysis of Thin Film/Polydimethylsiloxane Substrate Structures in Curved State with Finite Thickness

by Haohao Bi, Wenjie Li and Liuyun Wang

Polymers 2026, 18(3), 411; https://doi.org/10.3390/polym18030411 - 5 Feb 2026

Viewed by 417

Abstract

Curved sensors hold significant positions in various fields of modern science and technology, such as medical care, soft robotics, and electronic devices. Meanwhile, flexible electronic devices with film/polydimethylsiloxane substrate structures have been widely applied in the configuration design and performance enhancement of sensors. [...] Read more.

Curved sensors hold significant positions in various fields of modern science and technology, such as medical care, soft robotics, and electronic devices. Meanwhile, flexible electronic devices with film/polydimethylsiloxane substrate structures have been widely applied in the configuration design and performance enhancement of sensors. It is essential to consider the dynamic buckling behavior of film/substrate structures under bending conditions for the optimization of sensor functions. In this study, the dynamic behaviors of thin film/substrate structures with finite thickness in the curved state are investigated. Firstly, the dynamic equations considering damping and external excitation are established based on the principle of minimum energy and the Lagrange function. Secondly, the dynamic responses under different parameters are analyzed. Finally, the effects of the frequency of external excitation, pre-strain, the amplitude of external excitation strain, and the Young’s modulus and thickness of the substrate on the critical value of chaos occurrence are discussed respectively. This study is aimed at providing novel insights for the design of curved sensors based on thin film/substrate structures. Full article

(This article belongs to the Special Issue Dynamic Behavior of Polymer Composite Materials and Structures, 2nd Edition)

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19 pages, 7070 KB

Open AccessArticle

Synergistic Optimization of the Properties of Fiber-Content-Dependent PPS/PTFE/MoS₂ Self-Lubricating Composites

by Zheng Wang, Shuangshuang Li, Liangshuo Zhao, Yingjie Qiao, Yan Wu, Zhijie Yan, Zhongtian Yin, Peng Wang, Xin Zhang, Xiaotian Bian, Lei Shi, Jiajie He, Shujing Yue and Zhaoding Yao

Polymers 2026, 18(3), 410; https://doi.org/10.3390/polym18030410 - 4 Feb 2026

Viewed by 534

Abstract

This study systematically investigates the influence of short carbon-fiber (SCF) content on the mechanical, thermal, and tribological properties of self-lubricating polyphenylene sulfide (PPS) composites filled with PTFE and MoS2, addressing the critical need for high-wear resistance in Carbon-Fiber-Reinforced Thermoplastic (CFRTP) structural applications. The [...] Read more.

This study systematically investigates the influence of short carbon-fiber (SCF) content on the mechanical, thermal, and tribological properties of self-lubricating polyphenylene sulfide (PPS) composites filled with PTFE and MoS2, addressing the critical need for high-wear resistance in Carbon-Fiber-Reinforced Thermoplastic (CFRTP) structural applications. The results identified 10 wt% SCF as the optimal content that achieved the best balance between load-bearing capacity and friction performance. The coefficient of friction μ and wear amount were reduced by 29.28% and 29.29%, respectively, compared to the PPS/PTFE/MoS2 composite material without SCF, and by 14.67% and 20.75%, respectively, compared to the material with excessive SCF filling (20 wt%). Finite-Element Analysis-Representative Volume Element (FEA-RVE) reveals the mechanism by which excessive content of SCF at the microscopic level leads to a slight decrease in mechanical properties. Critically, the tribological performance exhibited a discrepancy with bulk mechanical properties: above 15 wt% SCF, the wear rate worsened despite high mechanical strength, revealing that increased fiber agglomeration and micro-abrasion effects were the primary causes of performance deterioration. Further in-depth XPS analysis revealed a synergistic lubrication mechanism: In the optimal sample, an ultra-dense PTFE transfer film was formed to mask the underlying MoS2. This masking, coupled with the high surface activity of MoO3 particles leads to stronger physicochemical interactions with the polymer matrix, ensures the exceptional durability and stability of the tribo-film. This research establishes a complete structure–performance relationship by integrating mechanical, thermal, and tribo–chemical mechanisms, offering critical theoretical guidance for the design of next-generation high-performance self-lubricating CFRTPs. Full article

(This article belongs to the Special Issue Dynamic Behavior of Polymer Composite Materials and Structures, 2nd Edition)

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30 pages, 10018 KB

Open AccessArticle

Taming Waste Heterogeneity for Plastics Circularity with Optimized Sample Preparation Protocols for Quality Assessment

by Christos Panagiotopoulos, Christina Podara, Eleni Gkartzou, Melpo Karamitrou, Tatjana Kosanovic-Milickovic, Mara Silber, Lars Meyer, Bernhard von Vacano, Ana Rita Carvalho Neiva, Jan-Hendrik Knoop, Asunción Martínez-García, Ana Ibáñez-García, Silvia Pavlidou, Leila Poudeh, Costas A. Charitidis and Stamatina N. Vouyiouka

Polymers 2026, 18(3), 409; https://doi.org/10.3390/polym18030409 - 4 Feb 2026

Viewed by 1038

Abstract

From the perspective of the circular economy and minimization of environmental pollution, recycling plastics is key for transforming polymeric waste streams (PWSs) towards reusable and, if possible, upgraded, value-added products. The low homogeneity of PWSs, even when sorted, complicates sampling, analytical characterization, processability, [...] Read more.

From the perspective of the circular economy and minimization of environmental pollution, recycling plastics is key for transforming polymeric waste streams (PWSs) towards reusable and, if possible, upgraded, value-added products. The low homogeneity of PWSs, even when sorted, complicates sampling, analytical characterization, processability, and quality assurance of the whole circular process. Therefore, sampling, sample preparation, and analysis methodologies that yield results accurate and representative enough to describe the contents and the safety of the bulk while being cost-effective are crucial. In this context, an experimental “model waste” approach was conceptualized to reliably assess and optimize sampling and sample preparation strategies towards specific goals, i.e., identifying and precisely quantifying different polymer types and non-polymeric contaminants (such as brominated flame retardants, BFR) along with establishing a correlation of the sample preparation steps with low deviation values between replicates. The results indicated that cryogenic grinding better preserved additive content, minimizing its degradation, i.e., 461 ± 17 ppm determined via HPLC-MS when the nominal concentration was 500 ppm. On the other hand, melt-based homogenization significantly improved homogeneity and hence reproducibility/variability of analytical results (RSD), albeit at the risk of partial additive thermal degradation (up to 70% reduction in BFR content). The current experimental approach allows a clear understanding of plastic waste characteristics in view of demonstrating analytical limits of detection (LoD), reliable verification of compliance with certain concentrations of unwanted contaminants, and eventually robust evaluation of the applied recycling scheme efficiency. Full article

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

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19 pages, 9644 KB

Open AccessArticle

Contrasting Catalytic Pathways in Lignin Pyrolysis: Deoxygenative Cracking over HZSM-5 Versus Repolymerization–Coking over Activated Carbon

by Hao Ma, Yue Hu, Huixia Zhu, Qimeng Jiang and Tianying Chen

Polymers 2026, 18(3), 408; https://doi.org/10.3390/polym18030408 - 4 Feb 2026

Cited by 1 | Viewed by 619

Abstract

Catalytic pyrolysis is a crucial technology for lignin valorization, where the catalyst support itself can play a pivotal role in influencing the catalytic process. This study systematically investigates and compares the distinct catalytic effects of two commonly used catalyst supports, HZSM-5 zeolite and [...] Read more.

Catalytic pyrolysis is a crucial technology for lignin valorization, where the catalyst support itself can play a pivotal role in influencing the catalytic process. This study systematically investigates and compares the distinct catalytic effects of two commonly used catalyst supports, HZSM-5 zeolite and activated carbon (AC), during lignin pyrolysis. Macrokinetic analysis was conducted using TGA coupled with the Friedman kinetic model to determine the apparent activation energies (Ea) and coke yields. The evolution of functional groups was analyzed using Py-GC/MS coupled with quantitative functional group indexing. Additionally, the evolution of small-molecule gases during catalytic pyrolysis was monitored using TGA-FTIR. The results demonstrate differences in the catalytic pathways promoted by HZSM-5 and AC. HZSM-5 effectively deoxygenated lignin by removing methoxy and hydroxyl groups, resulting in a reduction in Ea by 83 kJ/mol at 80% conversion and suppression of coke formation. In contrast, AC, exploiting its large specific surface area as a reaction platform, promoted the conversion of methoxy groups into methyl and hydroxyl functional groups, rather than directly removing them. Moreover, the use of AC led to a marked increase in Ea, and the coke yield increased by 2.5%. This study provides valuable insights for the rational design of efficient catalyst systems for biomass conversion. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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18 pages, 913 KB

Open AccessReview

Advances in Anti-Wrinkle Finishing Agent for Natural Fabrics

by Haoqian Luo, Haifeng Sun, Man Zhang, Jiating Wen, Mengmeng Chen, Jian Fang and Zhe Sun

Polymers 2026, 18(3), 407; https://doi.org/10.3390/polym18030407 - 4 Feb 2026

Viewed by 734

Abstract

Natural fabrics such as cotton and silk have been widely used due to their excellent properties, but their tendency to wrinkle limits their value. Traditional anti-wrinkle finishing agents suffer from issues like formaldehyde release and performance imbalance. This paper reviews the advances in [...] Read more.

Natural fabrics such as cotton and silk have been widely used due to their excellent properties, but their tendency to wrinkle limits their value. Traditional anti-wrinkle finishing agents suffer from issues like formaldehyde release and performance imbalance. This paper reviews the advances in anti-wrinkle finishing of cotton and silk fabrics, analyzing from the perspectives of environmentally friendly finishing agents, physical properties balancing, sustainable anti-wrinkle finishing, and synchronized multi-functionality. Current research have developed various environmentally friendly formaldehyde-free finishing agents, such as carboxylated polyaldehyde sucrose and α-lipoic acid, through strategies including natural product modification and organic–inorganic hybridization. The application of these agents can enable fabrics to achieve a balance between wrinkle resistance, mechanical properties, hydrophilicity, and resistance to yellowing properties. Simultaneously, they also overcome the limitations of traditional processes, endow fabric with integrated application of wrinkle resistance alongside functions such as dyeing, flame retardancy, and antibacterial properties. Moreover, optimization methods such as response surface methodology (RSM) have facilitated the precise regulation of process parameters. Future research should continue to focus on greenization, high performance, and multi-functional coordination, deepen molecular design and process optimization, and provide support for the sustainable development of the textile industry. Full article

(This article belongs to the Section Polymer Applications)

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41 pages, 22309 KB

Open AccessArticle

Effects of Pressurized Water Aging on Reciprocating Friction and Wear of FDM 3D-Printed PLA and Glass Fiber Reinforced PLA Composites

by Sinan Fidan, Satılmış Ürgün, Nevin Gamze Karsli, Taner Yilmaz, Mustafa Özgür Bora and Mehmet İskender Özsoy

Polymers 2026, 18(3), 406; https://doi.org/10.3390/polym18030406 - 4 Feb 2026

Viewed by 769

Abstract

This study evaluates 10 bar water aging effects on reciprocating tribology of FDM-printed PLA and PLA with 10 and 15 wt.% glass fiber (GF). Water uptake was Fickian, and saturation mass rose from 0.0845 g (PLA) to 0.1625 g and 0.295 g (10 [...] Read more.

This study evaluates 10 bar water aging effects on reciprocating tribology of FDM-printed PLA and PLA with 10 and 15 wt.% glass fiber (GF). Water uptake was Fickian, and saturation mass rose from 0.0845 g (PLA) to 0.1625 g and 0.295 g (10 and 15 wt.% GF). Reciprocating tests at 40 N over 100 m at 0.5 and 1 Hz showed immersion time drives coefficient of friction (COF) and wear. At 0.5 Hz, neat PLA stabilized at COF 0.65 to 0.70 but increased to about 0.75 to 0.80 after 7-day; PLA + 10 wt.% GF reached about 0.80 to 0.82 after 14-day to 28-day. GF reduced unaged wear depth from about 125 µm to about 85 to 96 µm, yet 28-day aging increased depths to about 129 to 132 µm for both GF levels at 0.5 Hz. At 1 Hz, neat PLA peaked at about 235 to 240 µm depth after 7-day, whereas 15 wt.% GF reached about 160 µm after 28-day. Factorial analysis showed that wear scar width was primarily influenced by immersion time, accounting for 76.02% of the variation in the data, clearly evidencing strong dependence on the environment. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), glass transition temperature (Tg), and the melting temperature (Tm) support the occurrence of a transition from volume to interface-dominated damage with aging, while Tg and Tm remain unaffected. Full article

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

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34 pages, 6828 KB

Open AccessReview

0D Nanofillers in EPDM-Based Elastomeric Ablatives: A Review of Thermo-Ablative Performance and Char Formation

by Mohammed Meiirbekov, Marat Nurguzhin, Marat Janikeyev, Zhannat Kadyrov, Mukhammed Sadykov, Assem Kuandyk, Nurmakhan Yesbolov, Nurlybek Spandiyar, Meiir Nurzhanov and Sunkar Orazbek

Polymers 2026, 18(3), 405; https://doi.org/10.3390/polym18030405 - 4 Feb 2026

Viewed by 673

Abstract

EPDM is widely used as the polymer matrix for solid rocket motor (SRM) internal thermal protection because of its low density, chemical inertness, and ability to form carbonaceous residue. Practical performance is frequently limited by weak char integrity and barrier properties, char oxidation, [...] Read more.

EPDM is widely used as the polymer matrix for solid rocket motor (SRM) internal thermal protection because of its low density, chemical inertness, and ability to form carbonaceous residue. Practical performance is frequently limited by weak char integrity and barrier properties, char oxidation, mechanical stripping in gas-dynamic flow, and by the poor comparability of published results due to non-uniform test conditions and reporting. This review systematizes studies on 0D nanofillers in EPDM ablatives and harmonizes the key metrics, including linear and mass ablation rates (LAR, MAR), back-face temperature (T_back), and solid residue yield. The major 0D additives-nSiO₂, nTiO₂, nZnO, and carbon black (CB) are compared, and their dominant mechanisms are summarized: degradation-layer structuring, reduced gas permeability, thermo-oxidative stabilization, and effects on vulcanization. Several studies report larger improvements for hybrid systems, where CB enhances char cohesion and retention, while oxide nanoparticles improve barrier performance and resistance to oxidation. Finally, an application-oriented selection matrix is proposed that accounts for thermal protection efficiency, processability, agglomeration limits, and density penalties to support EPDM coating design and improve comparability. Full article

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

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17 pages, 4141 KB

Open AccessArticle

Numerical Simulation of Failure Modes of Solid Propellants with Internal Cavities Under Various Loading Conditions

by Kai Liu, Qingchun Yang, Liang Cao, Jianru Wang and Peng Cao

Polymers 2026, 18(3), 404; https://doi.org/10.3390/polym18030404 - 4 Feb 2026

Viewed by 460

Abstract

The reliability of solid rocket motors depends primarily on the structural integrity of their propellants. Internal cavity defects in the widely used hydroxyl-terminated polybutadiene (HTPB) propellant, formed during manufacturing and service, significantly degrade its mechanical properties and compromise motor safety. This study developed [...] Read more.

The reliability of solid rocket motors depends primarily on the structural integrity of their propellants. Internal cavity defects in the widely used hydroxyl-terminated polybutadiene (HTPB) propellant, formed during manufacturing and service, significantly degrade its mechanical properties and compromise motor safety. This study developed a constitutive model for HTPB propellant based on the generalized incremental stress–strain damage model (GISSMO). The validity of the constitutive model was verified through uniaxial tensile tests conducted at various tensile rates. Based on this constitutive model, numerical simulations were performed to examine the effects of initial modulus, impact rate, and cavity confining pressure on the failure modes of propellants containing cavities with radii from 40 to 100 mm. The results show that the simulation’s force–displacement curve agrees well with the test. The simulation accurately captures the propellant’s transition from elastic–plastic plateau at low rates to elastic response at high rates. The prediction error for the maximum tensile force is less than 5%. For cavities of 80 mm and 100 mm, local stress concentration causes damage to the inner wall, followed by rapid cavity extrusion, collapse, and possible cross-shaped matrix fracture. However, cavities of 40 mm and 60 mm show greater stability, experiencing only volume compression, which rarely causes overall damage. When the propellant’s initial modulus is higher than 24 MPa, damage propagation in large cavities over 80 mm is suppressed. A low modulus worsens structural deformation. At low impact velocity, cavity compression is significant, and the structure remains conformal. At high impact velocity (4000 MPa/s), the cavity stays conformal, the matrix collapses, and the damage value decreases. For 60 mm cavities, damage is localized, and the overall structure is most stable within a confining pressure of 5 to 9.5 MPa. This study clarifies the interaction between engineering parameters and cavity size, providing a basis for optimizing the safety of the propellant structure. Full article

(This article belongs to the Section Polymer Physics and Theory)

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15 pages, 1444 KB

Open AccessArticle

Effect of Additional Light Curing on Color Stability and Degree of Conversion of Mono-Shade Resin Composites

by Fatih Bedir, Muhammet Karadaş, Makbule Gamze Atıcı Bedir and Alper Özdoğan

Polymers 2026, 18(3), 403; https://doi.org/10.3390/polym18030403 - 3 Feb 2026

Viewed by 672

Abstract

This study aims to examine the effect of additional light curing on the color stability and degree of conversion (DoC) of mono-shade resin composites cured using different light curing units and irradiation levels. Sixty-six disk-shaped samples were prepared for each of the mono-shade [...] Read more.

This study aims to examine the effect of additional light curing on the color stability and degree of conversion (DoC) of mono-shade resin composites cured using different light curing units and irradiation levels. Sixty-six disk-shaped samples were prepared for each of the mono-shade (Omnichroma/OC, Vittra APS Unique/VU) and multi-shade resin (Clearfil Majesty ES-2/CME) composites. The samples were randomly divided into three groups and cured for 20 s according to: (1) QTH at 800 mW/cm² (16 J/cm²), (2) LED at 1000 mW/cm² (20 J/cm²), and (3) 1400 mW/cm² (28 J/cm²). After polishing, half of the samples in each group were exposed to additional light curing. Color parameters were measured at baseline and after 28 days of immersion in a coffee solution. CIEDE2000 color (∆E₀₀) and Whiteness Index (ΔWI_D) changes were used to assess color stability. ∆E₀₀ and ΔWI_D were compared with the perceptibility and acceptability threshold. Mono-shade composites exhibited lower DoC with higher ΔE₀₀ and ΔWI_D changes compared to the multi-shade composite. Mono-shade composites showed clinically unacceptable color and whiteness changes. Additional light curing performed using the same protocol both before and after polishing did not contribute to the color/whiteness stability and DoC of either mono-shade or multi-shade resin composites. Full article

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

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20 pages, 4156 KB

Open AccessArticle

Functional Characterization and Antifungal Activity of Insect-Derived Chitinases Expressed in Pichia pastoris

by Katia Celina Santos Correa, Gabriel Henrique Ribeiro, Odair Correa Bueno, Luiz Alberto Colnago, Iran Malavazi and Dulce Helena Ferreira de Souza

Polymers 2026, 18(3), 402; https://doi.org/10.3390/polym18030402 - 3 Feb 2026

Viewed by 739

Abstract

Chitinases catalyze the hydrolysis of β-1,4-glycosidic bonds in chitin, a structural biopolymer synthesized by numerous organisms. Although these enzymes have been widely investigated, studies focusing on insect-derived chitinases remain limited. In this study, three recombinant chitinases from the leaf-cutter ant Atta sexdens were [...] Read more.

Chitinases catalyze the hydrolysis of β-1,4-glycosidic bonds in chitin, a structural biopolymer synthesized by numerous organisms. Although these enzymes have been widely investigated, studies focusing on insect-derived chitinases remain limited. In this study, three recombinant chitinases from the leaf-cutter ant Atta sexdens were cloned, expressed in Pichia pastoris, and biochemically characterized. The enzymes-AsChtII-C2B3 (one catalytic and three chitin-binding domains), AsChtII-C3C4 (two catalytic domains), and AsChtII-C5B1 (one catalytic and one binding domain), exhibited optimal activity at pH 4–5 and 50 °C using colloidal chitin as substrate. Chitinase activity on colloidal α-chitin was confirmed by ¹H NMR (proton nuclear magnetic resonance) spectroscopy, revealing GlcNAc concentrations of 0.41, 0.48, and 0.56 mmol L⁻¹ for AsChtII-C3C4, AsChtII-C2B3, and AsChtII-C5B1, respectively. Their antifungal activities were evaluated against the human pathogens Candida albicans and Aspergillus fumigatus, as well as the phytopathogen Lasiodiplodia theobromae. Distinct inhibition profiles were observed: AsChtII-C5B1 (150 µg/mL) showed the highest activity against C. albicans (87.6% inhibition), while AsChtII-C3C4 (25 µg/mL) was most effective against A. fumigatus (60% inhibition). Notably, only AsChtII-C2B3 inhibited L. theobromae growth, inducing severe hyphal deformations observed by scanning electron microscopy (SEM). These findings demonstrate that recombinant A. sexdens chitinases exhibit species-specific antifungal properties, underscoring their potential as biotechnological tools for medical and agricultural applications. Full article

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

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19 pages, 8824 KB

Open AccessArticle

Thermo-Mechanical Behavior of Carbon Fiber Composites Processed at Elevated Temperatures

by Larisa-Anda Stroe, Daniel-Eugeniu Crunteanu, Mihail Botan, Adriana Stefan and George Catalin Cristea

Polymers 2026, 18(3), 401; https://doi.org/10.3390/polym18030401 - 3 Feb 2026

Viewed by 618

Abstract

Out-of-autoclave (OoA) processing has emerged as a promising route for manufacturing high-performance polymer composites while reducing energy consumption and production complexity. The authors investigate the effect of curing temperature on the thermo-mechanical performances of carbon fiber-reinforced composites produced via resin infusion. Five laminates [...] Read more.

Out-of-autoclave (OoA) processing has emerged as a promising route for manufacturing high-performance polymer composites while reducing energy consumption and production complexity. The authors investigate the effect of curing temperature on the thermo-mechanical performances of carbon fiber-reinforced composites produced via resin infusion. Five laminates composed of six carbon fiber plies were arranged in a [90/0/45/−45/0/90] lay-up and infused with an epoxy resin cured at 25, 40, 50, 60, and 70 °C. The influence of the processed temperatures of the mechanical properties was evaluated through tensile and three-point bending tests, whereas thermal performance was analyzed using Heat Deflection Temperature (HDT) measurements and differential scanning calorimetry (DSC). The results demonstrate an improvement in stiffness, strength, and HDT with increasing the curing temperature, with the 40–50 °C range yielding the most balanced enhancement in mechanical and thermal responses. DSC analyses confirm that higher curing temperatures promote a more complete crosslinking reaction, consistent with the improved laminate performance. Overall, the findings highlight the critical role of controlled thermal curing in optimizing OoA polymer composite systems and support their suitability for energy-efficient applications. Full article

(This article belongs to the Special Issue Thermo-Mechanical and Physical Behavior of Advanced Polymeric Materials)

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16 pages, 1384 KB

Open AccessArticle

Mycelium-Based Composites Using Minimally Processed Industrial Hemp Biomass: Impact of Species and Feedstock Ratio on Mechanical Performance Compared to Polystyrene Packaging

by Radika Bhaskar, Tanisha Rutledge, Kevin Trangone and Oneal Latimore

Polymers 2026, 18(3), 400; https://doi.org/10.3390/polym18030400 - 3 Feb 2026

Viewed by 991

Abstract

Mycelium-based composites (MBCs\) are formed from lignocellulosic substrates and biopolymer matrices derived from fungal mycelium. Due to their low fossil energy demand and biodegradability, MBCs represent a versatile and sustainable material suitable for a range of applications, with increasing interest focused on packaging. [...] Read more.

Mycelium-based composites (MBCs\) are formed from lignocellulosic substrates and biopolymer matrices derived from fungal mycelium. Due to their low fossil energy demand and biodegradability, MBCs represent a versatile and sustainable material suitable for a range of applications, with increasing interest focused on packaging. Hemp fibers are an example of natural fibers with great promise as a substrate to improve the mechanical properties of MBCs. However, the separation of bast and hurd fiber requires processing and commercial-scale facilities that are logistically challenging and may be cost-prohibitive. Here, the potential for minimally processed hemp, with no separation of fibers, is evaluated for the first time to demonstrate feasibility as a substrate for MBCs. Screening included different fiber ratios combined with three different, locally available mushroom strains, which are among the most common in MBC research. The resulting MBCs were tested as an alternative to environmentally harmful expanded polystyrene (EPS, or polystyrene foam), with a focus on compressive strength to reflect load-bearing performance. Some MBCs revealed mechanical performance that met or exceeded EPS, demonstrating the utility of minimally processed hemp fiber in biocomposites for safer packaging. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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17 pages, 10139 KB

Open AccessArticle

Curcumin-Based Tri-Allyl Derivative for Bismaleimide Resins: Synergistic Modulation of Thermal Stability and Fire Safety

by Hui Liu, Teresa Olszewska and Hao Liu

Polymers 2026, 18(3), 399; https://doi.org/10.3390/polym18030399 - 3 Feb 2026

Viewed by 549

Abstract

Bio-based bismaleimide (BMI) resins can reduce environmental impact and impart intrinsic flame retardancy, but achieving a high glass transition temperature (Tg) remains challenging. Here, we replace the conventional petrochemical co-monomer O,O′-diallyl bisphenol A (DABPA) with a synthesized tri-allyl derivative of curcumin [...] Read more.

Bio-based bismaleimide (BMI) resins can reduce environmental impact and impart intrinsic flame retardancy, but achieving a high glass transition temperature (Tg) remains challenging. Here, we replace the conventional petrochemical co-monomer O,O′-diallyl bisphenol A (DABPA) with a synthesized tri-allyl derivative of curcumin (AEC) in 4,4′-bismaleimidodiphenylmethane (BDM)-based resins. The AEC monomer, synthesized via exhaustive O- and C-alkylation of curcumin, acts as a trifunctional crosslinker. By systematically varying the imide:allyl molar ratio, we optimized the network properties. We optimize the network’s thermal and fire-safety properties. The optimized formulation (BDM: AEC = 1:0.87, denoted BA-0.87) yields 43.06% char at 800 °C and reduces the peak heat release rate (PHRR) by 13.2% compared to the conventional BDM/DABPA control (BD-0.87). Meanwhile, BA-0.87 passes UL-94 V-0 with no dripping and attains a Tg above 400 °C—nearly 100 °C higher than BD-0.87. These enhancements arise from curcumin’s rigid conjugated structure, which increases crosslink density and promotes char formation during decomposition. Our work demonstrates a viable, bio-derived pathway to engineer BMI resins that simultaneously improve thermal stability and intrinsic flame retardancy. Such resins are promising for demanding aerospace and high-temperature electronic applications that require both fire safety and stability. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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14 pages, 3969 KB

Open AccessArticle

PLLA/Simvastatin-Loaded Mesoporous Bioactive Glass Nanofibrous Scaffolds with Improved Osteogenic Activity and Mechanical Properties for Bone Tissue Engineering

by Wanqing Zhan, Qiqi Wen, Haiyan Yao and Junchao Wei

Polymers 2026, 18(3), 398; https://doi.org/10.3390/polym18030398 - 3 Feb 2026

Viewed by 555

Abstract

Insufficient osteogenic activity and mechanical properties of poly-L-lactic acid (PLLA) are urgent problems to be solved in deepening their application in bone tissue engineering. In this work, PLLA/mesoporous bioactive glass (PLLA/MBG) scaffolds and PLLA/simvastatin-loaded mesoporous bioactive glass (PLLA/MBG@SIM) scaffolds with filler content of [...] Read more.

Insufficient osteogenic activity and mechanical properties of poly-L-lactic acid (PLLA) are urgent problems to be solved in deepening their application in bone tissue engineering. In this work, PLLA/mesoporous bioactive glass (PLLA/MBG) scaffolds and PLLA/simvastatin-loaded mesoporous bioactive glass (PLLA/MBG@SIM) scaffolds with filler content of 5, 10, and 15 wt% MBG and MBG@SIM were fabricated via electrospinning technology. At 10 wt% MBG loading, the tensile strength and tensile modulus were 3.23 ± 0.26 MPa and 124.47 ± 8.68 MPa, respectively, over 50% higher than those of PLLA scaffolds, demonstrating a significant enhancement in mechanical properties. Moreover, the incorporation of MBG improved the bioactivity of the PLLA scaffold, promoting the formation of apatite on the surface of the scaffolds. All composite scaffolds were non-toxic with good biocompatibility. Furthermore, PLLA/MBG@SIM composite scaffolds displayed superior osteogenic effects, better than the pure PLLA scaffolds and PLLA/MBG scaffolds. This work presents a multifunctional scaffold system combining enhanced mechanical strength with potent osteogenic activity, showing great promise for bone tissue engineering applications. Full article

(This article belongs to the Special Issue Advanced Polymeric Composites in Dentistry: Synthesis, Properties and Applications)

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37 pages, 1597 KB

Open AccessSystematic Review

Bioactive Polymer Composites for 3D-Printed Bone Implants: A Systematic Review

by Anastassiya Khrustaleva, Dmitriy Khrustalev, Azamat Yedrissov, Polina Rusyaeva, Artyom Savelyev, Marlen Kiikbayev, Kristina Perepelitsyna and Vladimir Kazantsev

Polymers 2026, 18(3), 397; https://doi.org/10.3390/polym18030397 - 3 Feb 2026

Cited by 2 | Viewed by 1376

Abstract

Polymer-based bioactive composites are one of the most rapidly advancing areas in contemporary regenerative medicine. This review aims to identify major trends and knowledge gaps in the development of bioactive polymer composites and examine their translational relevance from a materials design perspective, with [...] Read more.

Polymer-based bioactive composites are one of the most rapidly advancing areas in contemporary regenerative medicine. This review aims to identify major trends and knowledge gaps in the development of bioactive polymer composites and examine their translational relevance from a materials design perspective, with a specific focus on synthetic thermoplastic polymer matrices suitable for load-bearing bone scaffold applications and filament-based additive manufacturing. A total of 546 publications spanning 2016–2025 were screened, with 106 selected according to predefined relevance criteria. Bibliometric and content analyses were performed to delineate the primary research trajectories of bioactive composite materials. The results revealed that the majority of studies focused on composites comprising synthetic aliphatic polyesters, primarily polylactic acid (PLA) or polycaprolactone (PCL), reinforced with hydroxyapatite (HA) or bioactive glass (BG), which confer osteoconductivity but rarely achieve multifunctionality. Antimicrobial agents, ion-releasing components, and naturally derived bioactive molecules—associated with biointeractive functionalities and reported effects related to osteogenesis, angiogenesis, and immune modulation—are significantly underrepresented. Fewer than 20% of the investigated studies include in vivo validation, underscoring considerable scope for further preclinical and translational research. This work consolidates current trends in synthetic bioactive polymer composite design and identifies critical directions for future research. The findings of this review provide a structured framework to support the selection of composite fabrication and modification strategies, functional additives, and targeted biological functionalities for next-generation, load-bearing bone tissue engineering materials. Full article

(This article belongs to the Section Polymer Applications)

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