Polymers

21 pages, 2551 KB

Open AccessFeature PaperArticle

Sulfonation-Time-Dependent Structure–Property Relationships of Electrospun Polyketone Nanofiber Membranes for PEMFC Applications

by Hongsik Byun, Geon-Hyeong Lee, Yeol-Lim Lee and Sang-Hun Lee

Polymers 2026, 18(12), 1542; https://doi.org/10.3390/polym18121542 (registering DOI) - 21 Jun 2026

Abstract

Electrospun sulfonated polyketone (PK) nanofiber membranes were prepared to investigate the sulfonation-time-dependent structure–property relationships of hydrocarbon-based polymer electrolyte membranes for PEMFC (Polymer Electrolyte Membrane Fuel Cell) applications. NaCl addition to the electrospinning solution increased solution conductivity and enabled the formation of uniform PK [...] Read more.

Electrospun sulfonated polyketone (PK) nanofiber membranes were prepared to investigate the sulfonation-time-dependent structure–property relationships of hydrocarbon-based polymer electrolyte membranes for PEMFC (Polymer Electrolyte Membrane Fuel Cell) applications. NaCl addition to the electrospinning solution increased solution conductivity and enabled the formation of uniform PK nanofibers with an average diameter of approximately 270 nm. Subsequent sulfonation introduced sulfonic-acid-related groups into the PK nanofiber framework, and the resulting membrane properties were strongly governed by sulfonation time. Among the tested membranes, PK-NC16 exhibited the highest proton conductivity of 0.107 ± 0.031 S cm⁻¹ and an ion exchange capacity of 2.82 m_eq g⁻¹, exceeding or comparable to those of Nafion 115 under the tested conditions. FTIR-based analysis indicated that the relative sulfonation index increased up to 16 h, whereas extended sulfonation for 24 h generated additional sulfone/sulfonate-related bands, suggesting possible side reactions or structural changes under prolonged acid treatment. The high water uptake of PK-NC16 enhanced proton transport but also revealed a hydration-sensitive polymer network, as reflected by a voltage degradation rate of approximately −590 μV h⁻¹ during a 100 h short-term stability constant-current test. These results demonstrate that sulfonation time is a key parameter controlling the balance among ionic functionality, hydration, mechanical response, proton conductivity, and PEMFC-relevant single-cell performance in electrospun PK nanofiber membranes. Full article

(This article belongs to the Special Issue Multifunctional Application of Electrospun Fiber: 2nd Edition)

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15 pages, 4106 KB

Open AccessArticle

Eggshell Particle-Reinforced PVA/GO Hydrogel with Self-Healing Effect

by Banu Esencan Türkaslan and Merve Dogu

Polymers 2026, 18(12), 1541; https://doi.org/10.3390/polym18121541 (registering DOI) - 21 Jun 2026

Abstract

Self-healing biomaterials have attracted significant attention due to their ability to restore structural integrity, extend material lifetime, and reduce maintenance costs without external intervention. In this study, Polyvinyl Alcohol/Graphene Oxide/Eggshell Particle (PVA/GO/ESP) composite hydrogels were synthesized via a freeze–thawing method and characterized using [...] Read more.

Self-healing biomaterials have attracted significant attention due to their ability to restore structural integrity, extend material lifetime, and reduce maintenance costs without external intervention. In this study, Polyvinyl Alcohol/Graphene Oxide/Eggshell Particle (PVA/GO/ESP) composite hydrogels were synthesized via a freeze–thawing method and characterized using XRD, SEM/EDS, and FTIR analyses. The effect of ESP incorporation on the self-healing and mechanical properties of the hydrogels was systematically investigated. Tensile test results demonstrated that incorporation of 1 wt% ESP improved the tensile strength up to 0.326 MPa while maintaining high strain capacity. Healing efficiency values calculated from recovered tensile strength showed approximately 69%, 47%, and 67% recovery for PVA/GO, PVA/GO/ESP (0.5%), and PVA/GO/ESP (1%) hydrogels, respectively. The developed hydrogels demonstrated rapid self-healing behavior at room temperature without external stimuli. These findings suggest that ESP-reinforced PVA/GO hydrogels may serve as promising candidates for future biomaterial and soft tissue engineering studies. The developed hydrogels demonstrated enhanced tensile strength, rapid self-healing behavior, and promising swelling properties, indicating their potential use in soft tissue engineering and biomaterial applications. Full article

(This article belongs to the Special Issue Material-Process-Structure Integrated Design for Advanced Polymeric Composites, 2nd Edition)

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19 pages, 2944 KB

Open AccessArticle

Cell Structure Regulation of Polypropylene/Ethylene-Propylene Rubber Bead Foams and Enhanced Mechanical Properties of Their Molded Products

by Zi’ang Hu, Xiulu Gao, Yichong Chen, Jiacheng Wang, Ling Zhao and Dongdong Hu

Polymers 2026, 18(12), 1540; https://doi.org/10.3390/polym18121540 (registering DOI) - 21 Jun 2026

Abstract

To improve the foamability and steam-chest molding performance of polypropylene (PP) bead foams, ethylene-propylene rubber (EPR) was introduced into PP via melt blending. The role of EPR in the complete bead-foaming-to-molding process was systematically investigated by correlating phase morphology, crystallization behavior, melt viscoelasticity, [...] Read more.

To improve the foamability and steam-chest molding performance of polypropylene (PP) bead foams, ethylene-propylene rubber (EPR) was introduced into PP via melt blending. The role of EPR in the complete bead-foaming-to-molding process was systematically investigated by correlating phase morphology, crystallization behavior, melt viscoelasticity, CO₂ dissolution and diffusion, cellular structure, inter-bead welding, and the mechanical properties of molded foam products. The incorporation of EPR refined the PP crystalline morphology, reduced the apparent crystallinity, and markedly enhanced the melt viscoelasticity, thereby broadening the foaming temperature window. The dispersed EPR phase functioned simultaneously as a CO₂ reservoir and a high-diffusivity pathway of CO₂, which promoted cell growth while suppressing excessive nucleation. The enhanced melt viscoelasticity and improved CO₂ affinity promoted bead expansion and optimized the cellular structure. At 150 °C, the expansion ratio increased from 18.7 for neat PP to 21.1 with 10 wt% EPR. EPR also regulated the cellular structure. At 150 °C, the cell diameter increased from 83 to 176 μm as the EPR content increased from 0 to 20 wt%. EPR markedly changed the double-melting behavior of PP bead foams. The low-temperature melting enthalpy increased from 28.5 J/g for neat PP to 37.8 J/g with 10 wt% EPR, which served as an effective interfacial binder, significantly promoting inter-bead welding. Consequently, the optimized PP/EPR foam containing 10 wt% EPR exhibited a tensile strength of 1.13 MPa and an elongation at break of 22.1%. More importantly, excellent molding quality was achieved at a reduced steam pressure of 2.2 bar, demonstrating the great potential of PP/EPR bead foams for the energy-efficient manufacturing of high-performance lightweight products. Full article

(This article belongs to the Special Issue Advances in Thermoplastic Polymer Composites)

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22 pages, 2093 KB

Open AccessReview

Polymer-Based Coatings for Cardiovascular and Endovascular Devices: Linking Surface Chemistry, Drug Release Kinetics, and Thrombo-Inflammatory Performance: A Review

by Rasit Dinc and Nurittin Ardic

Polymers 2026, 18(12), 1539; https://doi.org/10.3390/polym18121539 (registering DOI) - 20 Jun 2026

Abstract

Polymer coatings are integral to nearly every modern cardiovascular and endovascular device, including drug-eluting stents (DESs) and drug-coated balloons (DCBs), bioabsorbable vascular scaffolds (BVSs), occluders, grafts, and catheter and guidewire hydrophilic surfaces. Persistent complications, including late stent thrombosis, delayed endothelialization, hypersensitivity, and restenosis, [...] Read more.

Polymer coatings are integral to nearly every modern cardiovascular and endovascular device, including drug-eluting stents (DESs) and drug-coated balloons (DCBs), bioabsorbable vascular scaffolds (BVSs), occluders, grafts, and catheter and guidewire hydrophilic surfaces. Persistent complications, including late stent thrombosis, delayed endothelialization, hypersensitivity, and restenosis, show that coatings actively shape biological responses rather than acting as inert drug carriers. Their surface chemistry, drug release kinetics, and degradation behavior are upstream determinants of blood– and tissue–material responses that govern healing and failure. This review frames coating selection as a structure–property–biological response problem. It surveys the major classes of synthetic polymer coatings and the defining surface and bulk properties. This review also examines how composition and architecture control drug release, and traces the interfacial cascade of protein adsorption, coagulation and complement activation, platelet and leukocyte responses, and neutrophil extracellular trap (NET) formation. These mechanisms are linked to contemporary design strategies that improve hemocompatibility, limit thrombosis, promote endothelial recovery, and tune degradation, and to the standardization and translation gaps that remain. The central message is that polymer coatings are not biologically equivalent. Their surface chemistries and degradation profiles determine the thrombo-inflammatory outcomes. Therefore, coating design should be guided by intended biological response, not drug release alone. Full article

(This article belongs to the Special Issue Polymer-Based Coatings: Principles, Development and Applications)

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31 pages, 20808 KB

Open AccessArticle

Fracture Mode Transition and Energy Dissipation of Brittle Coal Under Confinement Induced by a Flexible Polyurea Coating

by Shan Ning, Weibing Zhu, Biao Fu, Pengjun Gao and Zishuo Jia

Polymers 2026, 18(12), 1538; https://doi.org/10.3390/polym18121538 (registering DOI) - 20 Jun 2026

Abstract

Brittle geomaterials such as coal and rock are prone to unstable failure under high stress and dynamic disturbances, where rapid release of stored elastic strain energy can trigger dynamic disasters. Polyurea, a high-strength and high-ductility elastomer, can form a continuous flexible coating on [...] Read more.

Brittle geomaterials such as coal and rock are prone to unstable failure under high stress and dynamic disturbances, where rapid release of stored elastic strain energy can trigger dynamic disasters. Polyurea, a high-strength and high-ductility elastomer, can form a continuous flexible coating on the surface of coal/rock to regulate their deformation–fracture behavior. Here, uniaxial compression tests were performed on coal specimens coated with polyurea layers of different thicknesses (0–1.25 mm). Acoustic emission (AE) and digital image correlation (DIC) were jointly employed to characterize macroscopic deformation, microcrack evolution, fracture-mode transition, and energy partitioning. The results show that polyurea provides passive lateral confinement that suppresses lateral expansion and shifts macroscopic failure from brittle splitting to progressive ductile damage. AE-based AF–RA analysis indicates that thicker coatings increase the normal stress and shear resistance along potential fracture planes, promoting a microfracture transition from shear-dominated to tension-dominated cracking. Energy analysis demonstrates that the coating enhances pre-peak energy dissipation via coordinated deformation with the coal, while thicker coatings (≥1.00 mm) exhibit pronounced post-peak elastic tensile deformation to absorb and buffer fracture-released energy, impeding the instantaneous energy release typical of bare coal. Moreover, the elastic energy index shows that polyurea markedly reduces impact tendency, with an appropriate thickness stabilizing specimens from strong to weak/non-impact propensity. These findings clarify the coupled confinement–fracture–energy regulation mechanisms of polyurea coatings and provide quantitative guidance for coating-thickness design to mitigate dynamic failure hazards in brittle materials. Full article

(This article belongs to the Section Polymer Networks and Gels)

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23 pages, 2051 KB

Open AccessArticle

Lyophilized Chitosan-Based Hydrogels as a Potential Stimuli-Responsive Carrier System for Anti-Inflammatory Drugs: Ibuprofen Solubility Modulation at Variable pH of Simulated GIT Conditions

by Veronika Mikušová, Jarmila Prieložná, Dominika Žigrayová, Michal Hanko and Peter Mikuš

Polymers 2026, 18(12), 1537; https://doi.org/10.3390/polym18121537 (registering DOI) - 20 Jun 2026

Abstract

Poor aqueous solubility and consequently low bioavailability of various NSAIDs (non-steroidal anti-inflammatory drugs) usually result in high and multiple dosing with potentially serious side effects. Therefore, systems for the effective transport of NSAIDs through the GIT (gastrointestinal tract), ensuring enhanced bioavailability, remain in [...] Read more.

Poor aqueous solubility and consequently low bioavailability of various NSAIDs (non-steroidal anti-inflammatory drugs) usually result in high and multiple dosing with potentially serious side effects. Therefore, systems for the effective transport of NSAIDs through the GIT (gastrointestinal tract), ensuring enhanced bioavailability, remain in high demand. In the present work, we studied chitosan (CS) hydrogel lyophilizates as carrier systems for a model NSAID, namely ibuprofen (IBU). The CS-IBU lyophilizates were prepared from homogeneous or heterogeneous CS-IBU hydrogels to assess their influence on the resulting lyophilizate microstructure and IBU dissolution profiles. To gain a complex view of the CS-IBU behavior and its practical consequences, dissolution profiles of free IBU (reference) and CS-associated IBU (CS-IBU) were examined and compared to each other at variable pH (1.2 and 6.5) in two separate dissolution systems and in one discontinuous dissolution system mimicking GIT conditions. The results of dissolution experiments were supported by kinetic model data. This study demonstrated that the dissolution of IBU from the CS-IBU lyophilizates is affected by two main pH-dependent competitive effects; i.e., dissolved CS acts as an IBU solubilizer and the undissolved CS matrix serves as an IBU trap, which could be used in the rational design of innovative stimuli (pH)-responsive oral dosage forms of IBU. Full article

(This article belongs to the Special Issue Bio-Based Polymeric Materials for Biomedical Applications)

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18 pages, 2807 KB

Open AccessArticle

Fully Aqueous Electrospinning of Binary PVP/Sodium-Alginate and PVP/Riboflavin Nanofibres: Additive Effects and UV-Assisted Processing

by Julia C. Andrade, Gilmar P. Thim, Fernando Cabral, Frank Jorg Clemens and Marcio Fredel

Polymers 2026, 18(12), 1536; https://doi.org/10.3390/polym18121536 (registering DOI) - 20 Jun 2026

Abstract

Electrospinning (ES) can produce nonwoven fibrous mats with high surface area and interconnected porosity, making them attractive for biomedical and functional material applications. However, conventional ES often relies on volatile organic solvents, raising safety, environmental, and translational concerns. Fully aqueous (“green”) ES offers [...] Read more.

Electrospinning (ES) can produce nonwoven fibrous mats with high surface area and interconnected porosity, making them attractive for biomedical and functional material applications. However, conventional ES often relies on volatile organic solvents, raising safety, environmental, and translational concerns. Fully aqueous (“green”) ES offers an appealing alternative, although many water-soluble polymers remain difficult to spin and may show limited stability under hydrated conditions. In this study, two fully aqueous binary systems, poly(vinylpyrrolidone)–sodium alginate (PVP–SA) and poly(vinylpyrrolidone)–riboflavin (PVP–RF), were investigated to decouple the roles of sodium alginate (SA) and riboflavin (RF) on solution behaviour, fibre formation, morphology, dry-state mechanical properties, and surface chemistry. Aqueous PVP solutions (20% w/v; molecular weight 1.3 MDa) were blended with SA (1–5 wt% relative to PVP) or RF (1–10 wt% relative to PVP). Electrical conductivity and rheological properties were evaluated prior to ES under controlled conditions, with simultaneous ultraviolet (UV) exposure at 344 nm during fibre collection. RF did not significantly alter conductivity (~0.74–0.75 µS·cm⁻¹), whereas SA increased conductivity up to 2.75 ± 0.03 µS·cm⁻¹ at 5 wt%. All formulations exhibited shear-thinning behaviour, while 10 wt% RF increased the zero-shear viscosity relative to neat PVP. Morphological analysis showed that low SA contents produced uniform fibres, whereas higher SA levels (4–5 wt%) led to bead defects and reduced fibre diameter (down to 85 ± 25 nm). Dry-state mechanical performance decreased with increasing SA content, while 10 wt% RF improved tensile strength and toughness, reaching an ultimate tensile strength of 5.21 ± 0.15 MPa and toughness of 40.51 ± 1.53 MJ·m⁻³. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated subtle UV-driven redistribution of surface chemical states, consistent with mild photo-oxidative microstructural modification rather than extensive covalent network formation. Because the UV irradiance was not directly measured and wet-state stability was not assessed, the UV-related findings are interpreted as preliminary chemical evidence rather than confirmation of stabilized fibre mats. Overall, this work establishes a solvent-free aqueous ES platform in which ionic and photoactive additives can be used to tailor fibre morphology, dry-state mechanical behaviour, and surface characteristics without toxic reagents. Full article

(This article belongs to the Special Issue Advances in Electrospun Polymeric Nanofibers)

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22 pages, 4243 KB

Open AccessArticle

Preparation of an MMT-Modified Hyperbranched Adsorbent and Its Application in the Selective Adsorption of Pb(II)

by Wei Gong, Shitong Xie, Meilan Li, Qiang Xie, Yinyin Zhou, Yutong Sun and Guochun Zhang

Polymers 2026, 18(12), 1535; https://doi.org/10.3390/polym18121535 (registering DOI) - 20 Jun 2026

Abstract

The P(IA-HBP-AA-AM)/MMT composite was successfully synthesized via in situ polymerization and characterized using FTIR, XRD, TGA, and other techniques. The material was then applied as an adsorbent for the removal of heavy metals from simulated mining-contaminated water (prepared based on the typical ionic [...] Read more.

The P(IA-HBP-AA-AM)/MMT composite was successfully synthesized via in situ polymerization and characterized using FTIR, XRD, TGA, and other techniques. The material was then applied as an adsorbent for the removal of heavy metals from simulated mining-contaminated water (prepared based on the typical ionic composition of real mining wastewater). Static adsorption experiments revealed that P(IA-HBP-AA-AM)/MMT composite could efficiently remove Pb(II) from contaminated water, and the adsorption behavior was well described by the pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic analysis indicated that the adsorption of Pb(II) onto the P(IA-HBP-AA-AM)/MMT composite was an endothermic and spontaneous process. At pH = 4.5 and T = 45 °C, the maximum adsorption capacity obtained from model fitting was 249.38 mg/g. The material exhibited strong selectivity for Pb(II), even in the presence of competing metal ions such as Cd(II), Zn(II), Al(III), Fe(III), K(I), and Na(I). Moreover, after five adsorption–desorption cycles, it still retained approximately 90% of its Pb(II) removal efficiency. Furthermore, dynamic adsorption experiments showed that the saturation adsorption capacity of Pb(II) reached 178.7 mg/g, with a column utilization efficiency of approximately 41%. These findings demonstrate the promising potential of P(IA-HBP-AA-AM)/MMT composite for the removal of Pb(II) from mining-contaminated water. Full article

(This article belongs to the Collection Polymer Applications in Environmental Science)

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18 pages, 24432 KB

Open AccessArticle

Degradable Polyurethane Foams Based on Amino Acid Phosphoramides (APtA)

by Nico Vennemann, Anton Bauer and Oliver Brüggemann

Polymers 2026, 18(12), 1534; https://doi.org/10.3390/polym18121534 (registering DOI) - 20 Jun 2026

Abstract

Soft polyurethane foams are commonly found in furniture, mattresses, shoes and soundproofing applications. These crosslinked foams are hard to recycle. This paper describes our approach of introducing chemical breakage points based on amino acid phosphoramidates (APtA) in the PUs’ backbones. The APtA monomers [...] Read more.

Soft polyurethane foams are commonly found in furniture, mattresses, shoes and soundproofing applications. These crosslinked foams are hard to recycle. This paper describes our approach of introducing chemical breakage points based on amino acid phosphoramidates (APtA) in the PUs’ backbones. The APtA monomers are combined with PEG, PPG and pTHF-chains to achieve different monomer structures. We demonstrate the hydrolysis of these APtA monomers at neutral pH 7 and the mass loss of the foams. It is shown that after 70 days, more than 50% of the p-THF-APtA monomer and 35% of the PPG-APtA monomer have degraded. However, a contrary trend was observed for the foams, with only 2.5% mass loss for the p-THF-APtA foam, but 26% mass loss for the PPG-APtA foam. The foams were also characterized using compression measurements, revealing a stiffer appearance of the p-THF-APtA foam compared to the foams based on PEG and PPG. SEM images were taken before and after the degradation of the foams to show the difference in morphology. Full article

(This article belongs to the Section Circular and Green Sustainable Polymer Science)

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9 pages, 1807 KB

Open AccessArticle

Laser-Induced Nanocarbon Films Enable Optical Sensor Based on Combined Photothermal and Piezoresistive Effect

by Yanbo Yao, Jingwen Yao and Tao Liu

Polymers 2026, 18(12), 1533; https://doi.org/10.3390/polym18121533 (registering DOI) - 19 Jun 2026

Abstract

This work presents an enhanced photomechanical optical sensor inspired by our previously reported bio-inspired uncooled infrared detector. Performance improvement is achieved by strengthening the interfacial bond between the photothermal dendrite—polydopamine nanoparticle (PDA NP)/polydimethylsiloxane (PDMS) composite—and the piezoresistive laser-induced nanocarbon film, with a flexible [...] Read more.

This work presents an enhanced photomechanical optical sensor inspired by our previously reported bio-inspired uncooled infrared detector. Performance improvement is achieved by strengthening the interfacial bond between the photothermal dendrite—polydopamine nanoparticle (PDA NP)/polydimethylsiloxane (PDMS) composite—and the piezoresistive laser-induced nanocarbon film, with a flexible PDMS substrate that provides both thermal insulation and mechanical stability. The resulting sensor exhibits a responsivity of 51.6 W⁻¹ under 808 nm irradiation, an order-of-magnitude enhancement over the unmodified device. Wavelength-dependent characterization (455–1550 nm) shows responsivity decreasing from 93.1 W⁻¹ at 455 nm to 14.4 W⁻¹ at 1550 nm, with response times on the order of seconds across this range. Extending this trend into the longer-wavelength region of blackbody radiation, the mechanism transitions to a predominantly bolometric mode. The device also demonstrates stable detection of several hundred microwatts and robust durability at 455 nm. These results validate interface engineering strategy as a viable pathway toward high-performance uncooled optical detection, advancing bio-inspired detectors from functional mimicry toward an application-ready platform. These findings confirm PDA NPs as effective photothermal converters primarily at shorter wavelengths, while the wavelength-dependent response suggests future tailoring of spectral sensitivity using long-wavelength-absorbing materials. Full article

(This article belongs to the Section Smart and Functional Polymers)

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29 pages, 2296 KB

Open AccessArticle

Advanced Digital Imaging Assessment Method for Testing Surface Fuzzing in Textile Materials

by Juro Živičnjak, Antoneta Tomljenović, Maja Somogyi Škoc and Željko Penava

Polymers 2026, 18(12), 1532; https://doi.org/10.3390/polym18121532 (registering DOI) - 19 Jun 2026

Abstract

Textile materials made from staple fibers typically have protruding fibers on their surface, commonly referred to as surface hairiness. During fraying, the surface of the textile material is susceptible to damage, which affects its appearance and leads to fuzzing by roughening or the [...] Read more.

Textile materials made from staple fibers typically have protruding fibers on their surface, commonly referred to as surface hairiness. During fraying, the surface of the textile material is susceptible to damage, which affects its appearance and leads to fuzzing by roughening or the emergence of new fibers. The propensity for fuzzing is assessed using the standard visual method (EN ISO 12945-4:2020), which is intuitive and cost-effective but better suited for evaluating more pronounced surface phenomena, such as pilling. This is mainly because fuzzing is usually accompanied by pilling, and their simultaneous occurrence makes separate analysis difficult. As a result, instrumental methods for assessing fuzzing that provide a more objective evaluation are rarely reported. In this research, an advanced digital imaging assessment method was introduced, using an innovative apparatus that, with simultaneous assessment of pilling, enabled separate digital imaging of the same textile fabric specimen’s surface fuzzing through a refined viewing angle. Additionally, newly developed software enabled digital analysis and acquisition of quantitative numerical values related to surface fuzzing. The research was conducted on six single-component woven fabrics made from cotton, wool, viscose, polyamide 6.6, polyester, and acrylic. Fuzzing was induced using an ICI tester (EN ISO 12945-1:2020) and a Martindale tester (EN ISO 12945-2:2020) through predefined box revolutions and fuzzing rubs ranging from 125 to 30,000. Fuzzing was assessed using both the standard visual method and the advanced digital imaging assessment method, with grading according to established classes based on the percentage change in fuzzing layer height. The results highlight the applicability of the advanced digital assessment method, as it separately captures the occurrence of fuzzing and distinguishes it from pilling. Full article

(This article belongs to the Special Issue Advancements in Mechanical Properties and Material Testing in Polymer Science, 2nd Edition)

25 pages, 18288 KB

Open AccessArticle

Infill Pattern-Dependent Mechanical Properties and In Vitro Release Behavior of FDM 3D-Printed Resveratrol Amorphous Solid Dispersion Matrix Tablets

by Lianghao Huang, Kai Zheng, Xiaofeng Chen, Yunping Zhao, Tiantian Yang, Hang Yu, Wei Zhao, Xia Zhao and Jiaxiang Zhang

Polymers 2026, 18(12), 1531; https://doi.org/10.3390/polym18121531 (registering DOI) - 19 Jun 2026

Abstract

Resveratrol (RSV) is a poorly water-soluble polyphenolic compound with various potential health benefits, but its pharmaceutical application is limited by low aqueous solubility and poor oral bioavailability. Additive manufacturing (AM), particularly fused deposition modeling (FDM) 3D printing, offers a flexible approach for fabricating [...] Read more.

Resveratrol (RSV) is a poorly water-soluble polyphenolic compound with various potential health benefits, but its pharmaceutical application is limited by low aqueous solubility and poor oral bioavailability. Additive manufacturing (AM), particularly fused deposition modeling (FDM) 3D printing, offers a flexible approach for fabricating oral dosage forms with customized geometry and internal architecture. In this study, hot-melt extrusion (HME) combined with fused deposition modeling (FDM) 3D printing was used to prepare RSV-loaded tablets with different infill patterns. Hydroxypropyl methylcellulose acetate succinate and hydroxypropyl cellulose were selected as polymeric carriers to prepare RSV-loaded filaments suitable for FDM printing. The effects of infill pattern on the solid-state characteristics, dimensional accuracy, mechanical properties, floating behavior, and in vitro drug release of the printed tablets were systematically investigated. Differential scanning calorimetry, powder X-ray diffraction, and polarized light microscopy indicated that RSV was mainly converted into an amorphous or molecularly dispersed state after HME and FDM processing. All designed tablets were successfully printed and showed acceptable shape fidelity, while different infill patterns resulted in variations in tablet weight, mechanical strength, floating duration, and release behavior. In vitro dissolution studies showed that the RSV release profiles were dependent on the internal infill architecture. Tablets with more complex infill patterns generally exhibited slower drug release, which may be related to differences in internal pore structure, medium penetration pathways, matrix hydration, and diffusion distance. Release kinetic analysis further suggested that RSV release from the printed tablets involved a combination of diffusion and polymer relaxation processes. These results demonstrate that infill pattern is an important structural parameter for modulating the mechanical performance and drug release behavior of FDM 3D-printed RSV tablets. This study provides useful guidance for the design of 3D-printed oral dosage forms with tunable release characteristics. Full article

(This article belongs to the Special Issue Advancements in Polymeric Materials for Precision Drug Delivery)

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22 pages, 32128 KB

Open AccessArticle

Atomistic Mechanisms of Silicone Rubber Degradation Under Coupled Temperature–Humidity–Electric Field Conditions

by Yiheng Zhou, Zhijun An, Yixin He, Cong Qian, Qiuhua Zhou, Wentian Zeng, Xinhan Qiao and Wenyu Ye

Polymers 2026, 18(12), 1530; https://doi.org/10.3390/polym18121530 (registering DOI) - 19 Jun 2026

Abstract

Silicone rubber is an important external insulating material for composite bushings, composite insulators, and other power equipment. During long-term service, it is inevitably exposed to coupled environmental and electrical stresses, such as elevated temperature, moisture ingress, strong electric fields, and partial discharge, which [...] Read more.

Silicone rubber is an important external insulating material for composite bushings, composite insulators, and other power equipment. During long-term service, it is inevitably exposed to coupled environmental and electrical stresses, such as elevated temperature, moisture ingress, strong electric fields, and partial discharge, which may lead to hydrophobicity loss, surface chalking, crack propagation, and particle shedding. To reveal the microscopic degradation mechanism of silicone rubber under complex operating conditions, a molecular model of methyl vinyl silicone rubber was constructed using Materials Studio. A stable silicone rubber molecular structure was obtained through crosslinking, geometry optimization, and ensemble relaxation. Subsequently, a reactive molecular dynamics simulation system under coupled temperature–humidity–electric field conditions was established using LAMMPS and the ReaxFF reactive force field. Different temperature gradients, electric field intensities, and aging–recovery stages were designed to investigate the degradation behavior of silicone rubber. The evolution of the maximum carbon content, maximum silicon content, carbon-containing decomposition products, and typical small-molecule products, including H₂, H₂O, CH₄, C₂H₂, C₂H₄, and C₂H₆, was statistically analyzed. In addition, atomic trajectory tracking was performed to clarify the processes of methyl group detachment, Si-O bond cleavage, water molecule participation, and molecular chain reconstruction. The results show that high temperature mainly promotes methyl group detachment from side chains and fracture of the siloxane main chain, while a strong electric field accelerates the decomposition process and induces the transformation of long siloxane chains into shorter chains. Water molecules can react with broken siloxane chains to form hydroxyl-containing structures, making the structural degradation partially irreversible. The degradation process of silicone rubber under coupled temperature–humidity–electric field stress can be summarized as side-chain detachment, main-chain scission, water-assisted reactions, free-radical recombination, and local molecular aggregation. This study provides a molecular-level theoretical basis for aging mechanism analysis, condition assessment, and lifetime prediction of composite external insulating materials. Full article

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

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18 pages, 17748 KB

Open AccessArticle

Bio-Based Nanocellulose Cryogels Modified with Tannin and Vanillin: Intermolecular Interactions and Functional Properties

by Lincoln Audrew Cordeiro, Alessandro Zanchin, Elena Colusso, Camila Monteiro Cholant, Patricia Oliveira Schmitt, Radmila Rodrigues Gravato, Lorenzo Moro, Mara Vegro, Sarah Kalli Silva da Silva, Amanda Marcely Reis, Jonas Raphael Eckardt, Lorenzo Guerrini, André Luiz Missio and Gianluca Tondi

Polymers 2026, 18(12), 1529; https://doi.org/10.3390/polym18121529 (registering DOI) - 19 Jun 2026

Abstract

Sustainable lightweight materials based on renewable resources have attracted increasing attention as alternatives to synthetic materials. However, developing nanocellulose cryogels with adequate structural integrity and efficient retention of phenolic compounds remains challenging, often requiring furanic and dialdehyde-based additives associated with environmental and health [...] Read more.

Sustainable lightweight materials based on renewable resources have attracted increasing attention as alternatives to synthetic materials. However, developing nanocellulose cryogels with adequate structural integrity and efficient retention of phenolic compounds remains challenging, often requiring furanic and dialdehyde-based additives associated with environmental and health concerns. In this context, tannin-containing nanocellulose cryogels were produced using vanillin and hydrogen peroxide as sustainable modification agents. The effects of the additives on the structural, morphological, colorimetric, mechanical, thermal, and leaching properties of the cryogels were investigated. FTIR and colorimetric analyses revealed the presence of phenolics and the effect of hydrogen peroxide. SEM analysis showed that tannin promoted structural densification, whereas peroxide induced fragmentation of the cryogel network and pore reorganization. These changes influenced density and mechanical performance, with nanocellulose-tannin exhibiting the highest compressive strength and elastic modulus. Thermal conductivity values remained within the range reported for highly porous lignocellulosic materials (38.93–43.79 (mW/m·K)). Tannin leaching demonstrated that peroxide significantly improved tannin retention, especially in the system including vanillin which exhibited only 13,61% tannin release. Overall, vanillin and hydrogen peroxide modified the supramolecular organization and functional properties of the cryogels, highlighting their potential as additives in porous materials for thermal insulation and adsorption applications. Full article

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

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22 pages, 5273 KB

Open AccessArticle

Structure–Property Relationships in PEI/PET Polymer Blends: Morphological, Rheological, Thermal, Mechanical Behavior, and Electromagnetic Response

by Elshod Olmosovich Khakberdiev, Hülya Kaftelen Odabaşı, Akın Odabaşı, Selcuk Helhel, Qodirbek Nuridin ugli Berdinazarov, Nizomiddin Zokir ugli Dusiyorov and Nigmat Rustamovich Ashurov

Polymers 2026, 18(12), 1528; https://doi.org/10.3390/polym18121528 - 19 Jun 2026

Abstract

In this study, twin screw extruded Polyetherimide (PEI)/Poly(ethylene terephthalate) (PET) polymer blends (90/10, 70/30, 50/50 w/w%) were investigated to elucidate the composition–property relationship governed by morphological, structural, rheological, thermomechanical, mechanical, and electromagnetic shielding (EMI) performance behavior. Among other polymer blends, [...] Read more.

In this study, twin screw extruded Polyetherimide (PEI)/Poly(ethylene terephthalate) (PET) polymer blends (90/10, 70/30, 50/50 w/w%) were investigated to elucidate the composition–property relationship governed by morphological, structural, rheological, thermomechanical, mechanical, and electromagnetic shielding (EMI) performance behavior. Among other polymer blends, the 70/30 blend exhibits superior thermomechanical stability with a significant glass transition temperature of 132.7 °C, where a robust confinement effect effectively restricts the mobility of PET chains. This morphology, characterized by a domain size of 562 nm, provides proof of concept for interface-driven attenuation, reaching a maximum EMI shielding effectiveness of 2.54 dB within the investigated blends. This performance is primarily governed by Maxwell–Wagner–Sillars polarization at the immiscible boundaries, alongside an optimized dielectric loss of tan δ ≈ 0.065. The design of these high-temperature PEI blends provides a proof of concept for interface-driven attenuation and demonstrates their potential for developing advanced EMI shielding matrices. Full article

(This article belongs to the Section Polymer Chemistry)

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20 pages, 22758 KB

Open AccessArticle

Ionic Liquid-Assisted Acetylated Xylan Coatings Reinforced with CuO and ZnO Nanoparticles for Food Packaging Papers

by Petronela Nechita and Silviu-Marian Năstac

Polymers 2026, 18(12), 1527; https://doi.org/10.3390/polym18121527 - 19 Jun 2026

Abstract

This study investigates the potential of xylan acetylated using imidazolium-based ionic liquids, particularly 1-ethyl-3-methylimidazolium acetate ([Emim]Ac), as a functional matrix for ZnO and CuO nanoparticles (ZnO NPs and CuO NPs) in composite coatings for food packaging paper. A single coating layer (approximately 5 [...] Read more.

This study investigates the potential of xylan acetylated using imidazolium-based ionic liquids, particularly 1-ethyl-3-methylimidazolium acetate ([Emim]Ac), as a functional matrix for ZnO and CuO nanoparticles (ZnO NPs and CuO NPs) in composite coatings for food packaging paper. A single coating layer (approximately 5 g/m²) was applied on both sides of the paper samples to improve barrier properties against water, oils, fats, and microbial contamination. The obtained results show that the combination of acetylated xylan with ZnO and CuO nanoparticles improved surface hydrophobicity, with contact angle values reaching 83° and 97°, respectively. The coatings exhibited antibacterial activity against Bacillus sp., as well as a reduction in fungal development of Penicillium spp., as evidenced by the observed inhibition of conidia sporulation. These findings indicate that ionic liquid-assisted acetylation of xylan using [Emim]Ac is an effective route for chemical modification of hemicelluloses. The developed xylan-based coatings demonstrate promising functional properties for potential application in sustainable food packaging materials, within the scope of the performed experiments. Full article

(This article belongs to the Special Issue Lignocellulosic Materials: From Fractionation to Multifunctional Applications)

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18 pages, 2207 KB

Open AccessArticle

Sodium Caseinate/Tea Polyphenols Stabilized Lavender Essential Oil Nanoemulsions: Preparation, Characterization, Antibacterial Activity and Potential as Natural Food Preservatives

by Yu Chen, Jiaxin He, Haiting Cai, Yanli Cai, Wei Liao, Adem Gharsallaoui, Kai Yang, Peilong Sun, Ming Cai and Jian Wang

Polymers 2026, 18(12), 1526; https://doi.org/10.3390/polym18121526 - 19 Jun 2026

Abstract

Excessive application of chemical preservatives has raised increasing concerns regarding food safety and human health, prompting the search for safer natural alternatives. Lavender essential oil (LEO), a plant-derived antimicrobial agent, has been considered a promising substitute for synthetic preservatives, but its high volatility [...] Read more.

Excessive application of chemical preservatives has raised increasing concerns regarding food safety and human health, prompting the search for safer natural alternatives. Lavender essential oil (LEO), a plant-derived antimicrobial agent, has been considered a promising substitute for synthetic preservatives, but its high volatility and poor water solubility limit its practical application. In this study, LEO nanoemulsions were fabricated via high-pressure homogenization using sodium caseinate (SC) and tea polyphenols (TPs) as composite emulsifiers. The preparation process was optimized using a three-factor, three-level orthogonal design, and the physicochemical properties, storage stability, and antibacterial activity were systematically investigated. The optimal preparation conditions were determined as an SC/TP mass ratio of 2:1, homogenization pressure of 70 MPa, and 7 homogenization cycles. The optimized nanoemulsion exhibited a droplet size of 130–210 nm, zeta potential of −30.89 mV, and encapsulation efficiency of 98.61%, with typical shear-thinning behavior and excellent storage stability. The percentage of free LEO remained below 7.5% within 15 days, indicating high stability, and the release behavior followed a zero-order kinetic model. The prepared nanoemulsion showed significant antibacterial activity against Staphylococcus aureus and Escherichia coli, with a minimum inhibitory concentration (MIC) of 62.5 μg/mL for both strains. This study confirms that the SC/TP composite interface can effectively stabilize LEO nanoemulsions, providing a theoretical basis for the development of natural and efficient food preservatives. Full article

(This article belongs to the Special Issue Biopolymers for Food Applications)

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19 pages, 3225 KB

Open AccessArticle

Sustainable Design of High-Performance Polyurethanes Using Medium-Chain-Length Polyhydroxyalkanoates

by Jasmina Nikodinovic-Runic, Chebrolu Venkateswara Rao, Maciej Guzik, Malgorzata Zimowska, Dusan Milivojevic and Marijana Ponjavic

Polymers 2026, 18(12), 1525; https://doi.org/10.3390/polym18121525 - 18 Jun 2026

Abstract

The transition toward a circular economy is accelerating the development of high-performance, sustainable polymeric materials derived from renewable resources. Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) represent a versatile class of biodegradable polyesters with inherent flexibility and tunable side-chain chemistry, making them attractive candidates for advanced polymer [...] Read more.

The transition toward a circular economy is accelerating the development of high-performance, sustainable polymeric materials derived from renewable resources. Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) represent a versatile class of biodegradable polyesters with inherent flexibility and tunable side-chain chemistry, making them attractive candidates for advanced polymer applications. Here, we report a novel class of bio-based polyurethanes (PUs) incorporating mcl-PHAs as soft segments, marking their first application in polyurethane synthesis and shifting towards greener PU synthesis. Polyurethane networks were prepared using castor oil (CO) and mcl-PHAs as polyols, with hexamethylene diisocyanate (HMDI) as a hard segment. Material properties were systematically tuned by varying the mcl-PHA/CO ratio (100/0 to 0/100), enabling precise control over structure–property relationships. Comprehensive characterization confirmed urethane bond formation and revealed predominantly amorphous materials with tunable thermal and mechanical behavior. Increasing mcl-PHA content enhanced elasticity and influenced phase organization, underscoring its role as a flexible, bio-derived soft segment. The resulting materials exhibited competitive mechanical performance alongside adjustable swelling behavior and morphology. Importantly, in vitro biocompatibility (MRC-5 fibroblasts) and eco-toxicological evaluation (Caenorhabditis elegans) confirmed the absence of toxicity. These findings highlight the potential of mcl-PHAs as sustainable building blocks for advanced polyurethane systems. Full article

(This article belongs to the Special Issue Advances in the Preparation, Properties and Application of Polyurethane, Cellulose and Their Composites (3rd Edition))

11 pages, 1010 KB

Open AccessCommunication

Accelerated-Aging Screening Data for Polymer Liners in Oil and Gas Flexible Composite Pipes: A Communication

by Pingyuan Xia, Tianyi Ma, Lin Lei, Qingxia Wang, Xiaomin Lu, Xiaolin Zhu, Yan Yan and Jiaqiao Zhang

Polymers 2026, 18(12), 1524; https://doi.org/10.3390/polym18121524 - 18 Jun 2026

Abstract

This Communication reports limited engineering screening data on polymer liner candidates for flexible composite pipes used in oil and gas service. Three exposure conditions were considered: hydrothermal aging in superheated water, thermal-oxidative aging in dry air, and hydrocarbon-medium exposure. Superheated-water immersion for up [...] Read more.

This Communication reports limited engineering screening data on polymer liner candidates for flexible composite pipes used in oil and gas service. Three exposure conditions were considered: hydrothermal aging in superheated water, thermal-oxidative aging in dry air, and hydrocarbon-medium exposure. Superheated-water immersion for up to 1000 h, dry-air aging for 168 h, and 7-day hydrocarbon exposure were used to describe changes in tensile properties, Shore hardness, mass, and thickness. Complete replicate records were available only for the thermal-oxidative aging dataset; therefore, most hydrothermal and hydrocarbon-medium results are reported as descriptive summary data. In the recorded data, EPDM formulation CL-2-1 retained approximately 89% of its tensile strength after 1000 h in superheated water. Sample L showed a smaller mean tensile-strength decrease than Sample Z after 168 h at 150 °C in dry air. In the hydrocarbon-medium summary data, XL95A/05B-S1 showed lower mass increase and smaller tensile-strength and yield-stress decreases than PERT XRT70H across the tested temperature range. The Communication provides case-specific screening evidence and identifies the need for replicated testing, statistical analysis, longer aging series, and structural characterization before general material-selection or durability conclusions are made. Full article

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

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