Polymers

16 pages, 2710 KB

Open AccessArticle

Preparation of Lignin-Based Phenolic Foam with Excellent Performance Based on Hydroxymethylation of Lignosulfonate and Paraformaldehyde

by Zhongbin Xu, Shushan Song, Xiang Zhen, Akram Ali Nasser Mansoor Al-Haimi, Zhongming Wang and Guocai Tian

Polymers 2026, 18(13), 1680; https://doi.org/10.3390/polym18131680 - 7 Jul 2026

Viewed by 574

Abstract

In this paper, a novel biobased phenol formaldehyde resin foam was fabricated. Specifically, lignosulfonate, a byproduct of paper and pulping, is hydroxymethylated with paraformaldehyde and then condensed with phenol to form lignosulfonate-based phenol formaldehyde (LPF) resin, subsequently undergoing foam technology to prepare LPF [...] Read more.

In this paper, a novel biobased phenol formaldehyde resin foam was fabricated. Specifically, lignosulfonate, a byproduct of paper and pulping, is hydroxymethylated with paraformaldehyde and then condensed with phenol to form lignosulfonate-based phenol formaldehyde (LPF) resin, subsequently undergoing foam technology to prepare LPF foam. The structures and properties of the intermediate and target products were characterized by ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry derivative thermogravimetry (TGA-DTG), scanning electron microscopy (SEM), compression performance test, limiting oxygen index test and thermal conductivity measurement. It was found that the prepared foam exhibited excellent mechanical and thermal properties. At a lignin substitution degree of 10%, the optimal thermal stability (at 800 °C), compressive strength (0.14 MPa) and thermal conductivity (0.0294 W/m·K) were achieved. As the lignosulfonate content gradually increases, the limit oxygen index initially showed a significant increase and then decreased. It is worth noting that when the LS substitution degree is increased to 30%, the limiting oxygen index of foam is up to 32.6%. These results underscore the application potential of industrial lignin as a promising biobased substitute in the synthesizing PF foam with excellent thermal insulation and flame-retardant properties. Full article

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

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20 pages, 1919 KB

Open AccessArticle

Gentamicin-Loaded Electrospun PVA/Kefiran/Schizophyllan Membrane for Skin Tissue Engineering Applications

by Karla Katiushka Solís-Arévalo, Luis J. Galán-Wong, Aida Rodriguez-Garcia and Katiushka Arévalo-Niño

Polymers 2026, 18(13), 1679; https://doi.org/10.3390/polym18131679 - 7 Jul 2026

Viewed by 447

Abstract

Healthcare-associated infections are prevalent in hospitals, clinics, and long-term care facilities. The use of wound dressings on active skin wounds, like burns, can cause damage to the skin barrier when removed for cleaning. Electrospun biodegradable and biocompatible membranes have emerged as promising alternatives [...] Read more.

Healthcare-associated infections are prevalent in hospitals, clinics, and long-term care facilities. The use of wound dressings on active skin wounds, like burns, can cause damage to the skin barrier when removed for cleaning. Electrospun biodegradable and biocompatible membranes have emerged as promising alternatives for wound dressing applications. In the present study, an electrospun membrane composed of polyvinyl alcohol/kefiran/schizophyllan loaded with gentamicin and ascorbic acid was developed. Kefiran was obtained from kefir with a 0.61% extraction yield. Beadless electrospun membranes with a diameter of 400 nm were obtained. Antimicrobial activity of the membrane against Staphylococcus aureus and Pseudomonas aeruginosa was determined. Growth inhibition halos of 16.4 ± 2.2 mm were found for Pseudomonas aeruginosa. Furthermore, the membrane cytocompatibility assay of the membrane showed no cell toxicity in human dermal fibroblasts (HDFn cells). The produced membranes showed potential to be used as a wound dressing material in the future. Full article

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

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19 pages, 3284 KB

Open AccessArticle

Mobility-Driven Design of PDMS-Modified Glassy Polymer Networks for Thermally Activated Shape Memory in Vat Photopolymerization

by Yura Choi and Namchul Cho

Polymers 2026, 18(13), 1678; https://doi.org/10.3390/polym18131678 - 7 Jul 2026

Viewed by 398

Abstract

Glass-transition-driven shape memory polymers are promising materials for 4D printing because their thermally activated transition enables programmed deformation and recovery without relying on melting or crystallization-driven switching. In this study, PDMS-MMA-modified photocurable networks were designed for vat photopolymerization-based 4D printing by varying PDMS-MMA [...] Read more.

Glass-transition-driven shape memory polymers are promising materials for 4D printing because their thermally activated transition enables programmed deformation and recovery without relying on melting or crystallization-driven switching. In this study, PDMS-MMA-modified photocurable networks were designed for vat photopolymerization-based 4D printing by varying PDMS-MMA content and switching monomer structure while maintaining a fixed TMPTMA crosslinker content. The resin formulations were prepared using tert-butyl acrylate (tBA) or isobornyl acrylate (IBOA) as switching monomers, PDMS-MMA as a flexible mobility-regulating segment, and TMPTMA as a multifunctional crosslinker. The effects of formulation composition on printability, network formation, thermal stability, thermomechanical transition, mechanical properties, and shape memory behavior were systematically investigated. FT-IR analysis confirmed effective photocuring of the acrylate/methacrylate networks, while rheological evaluation showed that resin viscosity depended on monomer structure and PDMS-MMA content. DMA results revealed thermomechanical transition, although some formulations exhibited broad tan δ responses due to network heterogeneity and distributed segmental relaxation. Based on resin printability, printed-part resolution, and relatively well-defined tan δ transitions, T-15 and I-15 were selected as representative formulations for quantitative shape memory evaluation. Shape memory testing was conducted under force-control mode because stable strain-controlled programming was not achievable for the printed specimens. Both T-15 and I-15 exhibited high shape fixity over two programming–recovery cycles. I-15 showed stable recovery behavior with recovery ratios of 91.51% and 95.87%, whereas T-15 showed apparent over-recovery with recovery ratios exceeding 100%, likely due to residual stress release during reheating. Overall, these results demonstrate that thermally activated shape-memory performance is governed not only by the nominal transition temperature but also by the coupled effects of PDMS-mediated segmental mobility, switching monomer structure, mechanical integrity, and elastic energy storage within a fixed crosslinked network framework. Full article

(This article belongs to the Special Issue Design and Sustainability: Polymer Composites via Additive Manufacturing)

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24 pages, 22245 KB

Open AccessArticle

Balsa Wood-Loaded Polyvinyl Alcohol/Chitosan/Zinc Gluconate Hydrogel Applied as Wound Dressing

by HanJiong Ji, Shengqiang Liao, Shibo Wu, Sijia Chen, Xue Guan, Chenlong Li and Dawei Zhang

Polymers 2026, 18(13), 1677; https://doi.org/10.3390/polym18131677 - 7 Jul 2026

Viewed by 490

Abstract

The skin is the largest organ of the human body and, due to its direct contact with the external environment, is one of the most vulnerable tissues. Traditional medical bandages and gauze exhibit limited efficacy in wound management, often neglecting the control of [...] Read more.

The skin is the largest organ of the human body and, due to its direct contact with the external environment, is one of the most vulnerable tissues. Traditional medical bandages and gauze exhibit limited efficacy in wound management, often neglecting the control of wound inflammation and the promotion of skin regeneration. Hydrogels, as an emerging material, possess appropriate swelling capacity, oxygen permeability, and the ability to absorb wound exudates, thereby facilitating wound healing, making them an ideal choice for functional applications in skin tissue engineering. In this study, dual-treated balsa wood (BWSM) was used as the hydrogel substrate, with polyvinyl alcohol (PVA), chitosan (CS), and zinc gluconate (ZnG) used as the primary raw materials. The BWSM/PVA/CS/ZnG hydrogel was prepared via gamma-ray irradiation. Balsa wood treated with alkaline solutions, hydrogen peroxide solutions, and microwave treatment processing exhibited enhanced transparency, increased porosity, improved thermal stability and swelling rates, while retaining adequate mechanical strength. Gamma-ray irradiation of the BWSM/PVA/CS/ZnG hydrogel wound dressing demonstrated sustained drug release and antibacterial efficacy through release and antimicrobial tests. Animal experiments showed that the BWSM/PVA/CS/ZnG composite hydrogel promoted wound healing in mice and effectively prevented scar formation. The aforementioned results demonstrate that the PVA/CS/ZnG composite hydrogel loaded with balsa wood exhibits durable antibacterial properties and high mechanical strength and promotes wound healing, making it suitable for applications in biomedical materials such as wound dressings. Full article

(This article belongs to the Special Issue Perspectives of Biopolymer Functionalization for New Materials)

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21 pages, 1918 KB

Open AccessArticle

Crystallization-Programmed Isotactic Polystyrene Towards Membrane Architecture: Quantitative Optical–Thermal Kinetics

by Al Mamun, Maha Alruwaili, Abdullah Al–Mamun, Md. Shafiquzzaman, Gary S. Coombs, Aljawad Mohammed Alolaywi and Amira Salman Alazmi

Polymers 2026, 18(13), 1676; https://doi.org/10.3390/polym18131676 - 7 Jul 2026

Viewed by 522

Abstract

Crystallization can be exploited as an architecture-forming step for polymer membranes because it builds a load-bearing semicrystalline scaffold while simultaneously defining amorphous regions that later become transport pathways. Herein, we quantify how thermal history programs isotactic polystyrene (iPS) crystallization and translate the resulting [...] Read more.

Crystallization can be exploited as an architecture-forming step for polymer membranes because it builds a load-bearing semicrystalline scaffold while simultaneously defining amorphous regions that later become transport pathways. Herein, we quantify how thermal history programs isotactic polystyrene (iPS) crystallization and translate the resulting microstructures into membrane-relevant design rules. Lux-calibrated digitally extracted pixel intensity (DPI) from polarized optical microscopy provides a quantitative, spatially resolved crystallinity proxy; benchmarking against differential scanning calorimetry confirms that the DPI proxy exhibits the same onset, peak, and completion signatures under matched temperature programs. The DPI–DSC agreement yielded R² = 0.98 under matched programs. We compared crystallization initiated from molten and glassy states across a wide range of melt pretreatments and crystallization temperatures. Molten-state pathways display pronounced melt-memory behavior: modest changes in melt pretreatment shift induction time and half-time and drive textures from dense, fine spherulitic fields to sparse, coarser morphologies. In contrast, glassy-state crystallization largely suppresses melt history, yielding overlapping sigmoidal crystallinity curves and stable kinetic parameters consistent with relaxation-mediated nucleation. Avrami analyses indicate three-dimensional growth in both routes but highlight the strong melt-history sensitivity of apparent rate constants in the molten state. The crystallization rate and half-life show bell-shaped temperature dependence. Finally, saturated nucleation density correlates with the melting response, providing a practical link between kinetic observables and morphology. The processing–morphology map provides membrane-relevant design rules by linking thermal history to nucleation density and scaffold texture, which are expected to influence transport and mechanical stability in downstream membrane fabrication. In this study, “membrane architecture” is used in a pre-fabrication sense to denote the crystallization-programmed semicrystalline scaffold expected to govern subsequent pore-generation behavior and mechanical stability. Accordingly, the present work establishes a quantitative process–structure map for iPS scaffold design. Full article

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

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11 pages, 7354 KB

Open AccessArticle

Flexible Polymer-Stabilized Liquid Crystal Films Based on Radical-Promoted Cationic Co-Polymerization of Epoxy Monomers for Smart Windows

by Bingxuan Wang, Tianfu Zhou, Jiayu Li, Yingjie Shi, Meiqi Yang, Yuxin Qian, Yanzi Gao, Meina Yu, Cheng Zou, Yuanwei Chen and Huai Yang

Polymers 2026, 18(13), 1675; https://doi.org/10.3390/polym18131675 - 7 Jul 2026

Viewed by 420

Abstract

Polymer-stabilized liquid crystal (PSLC) films are promising for smart window applications because of their transparent-to-scattering switching behavior. However, conventional acrylate-based PSLC films often suffer from poor mechanical robustness and weak interfacial adhesion, limiting their use in flexible devices. Herein, epoxy-based PSLC films have [...] Read more.

Polymer-stabilized liquid crystal (PSLC) films are promising for smart window applications because of their transparent-to-scattering switching behavior. However, conventional acrylate-based PSLC films often suffer from poor mechanical robustness and weak interfacial adhesion, limiting their use in flexible devices. Herein, epoxy-based PSLC films have been prepared through radical-promoted cationic photopolymerization using a difunctional epoxy monomer, E6M, and a series of liquid-crystalline monoepoxy monomers, E-nOCB. The effects of alkyl chain parity, chain length, and E6M/E-10OCB ratio on polymer morphology, electro-optical behavior, and peel strength were systematically investigated. Even-numbered E-nOCB monomers favored the formation of regular columnar polymer structures and improved optical contrast, whereas odd-numbered monomers produced more disordered networks with higher peel strength. Among them, the sample prepared with E-10OCB showed a better balance between electro-optical performance and mechanical adhesion. At a fixed total polymer content of 15 wt%, optimizing the E6M/E-10OCB ratio enabled the sample doped with E-10OCB to achieve the highest contrast ratio of 160.91 while increasing the peel strength from 47.28 to 55.69 kPa compared with the sample without E-10nOCB. These results demonstrate that regulating monoepoxy/diepoxy composition and alkyl chain structure is an effective strategy for improving the overall performance of epoxy-based PSLC films for smart windows. Full article

(This article belongs to the Special Issue Smart Polymers for Stimuli-Responsive Devices)

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25 pages, 28716 KB

Open AccessArticle

Poly(vinyl alcohol)-Controlled Spreading and Film Formation of Poly(3-hexylthiophene-2,5-diyl) at Liquid Interfaces: Influence of PVA Molecular Weight, Degree of Hydrolysis, and Concentration

by Ziyan Shi, Haibin Wang, Huibin Sun and Wei Huang

Polymers 2026, 18(13), 1674; https://doi.org/10.3390/polym18131674 - 7 Jul 2026

Viewed by 415

Abstract

The spreading and film formation of organic polymer solutions on liquid surfaces are key processes in coating, printing, and interfacial processing. However, the mechanisms by which aqueous polymers regulate spreading kinetics and film morphology are not yet fully understood. In this study, the [...] Read more.

The spreading and film formation of organic polymer solutions on liquid surfaces are key processes in coating, printing, and interfacial processing. However, the mechanisms by which aqueous polymers regulate spreading kinetics and film morphology are not yet fully understood. In this study, the free spreading of Poly(3-hexylthiophene-2,5-diyl) (P3HT)/chlorobenzene solution on poly(vinyl alcohol) (PVA) aqueous surface was employed as a model system to investigate how PVA concentration, molecular weight, degree of hydrolysis, and temperature collectively govern spreading behavior and film formation. Video recording was used to monitor the evolution of the spreading and front-edge morphology, while step-profilometry, UV–visible absorption spectroscopy, and atomic force microscopy were employed to characterize the resulting films in terms of thickness distribution, optical uniformity, and surface roughness. The results reveal that PVA can significantly regulate both the spreading kinetics of P3HT/chlorobenzene droplets and the final film morphology. PVA concentration exhibited a non-monotonic effect on spreading behavior, with intermediate concentrations favoring larger spreading areas and more continuous films. Increasing the PVA molecular weight altered the concentration-dependent spreading window and enhanced asymmetry at the spreading front, whereas reducing the degree of hydrolysis decreased interfacial tension and thereby increased the thermodynamic driving force for spreading, yet the actual spreading rate remained constrained by molecular diffusion, interfacial adsorption, and chain-segment rearrangement. Temperature and a saturated chlorobenzene vapor atmosphere further modulated the interplay among solvent evaporation, interfacial driving force, and viscous dissipation. Under optimized conditions, the resulting P3HT films displayed uniform thickness profiles, consistent optical absorption, and nanoscale surface roughness, and could be repeatedly transferred, assembled into well-defined multilayer structures, and printed onto flexible and curved substrates. These findings demonstrate that PVA aqueous subphase provides a tunable low-shear route for transferable P3HT thin-film fabrication and suggests its potential applicability to other polymer film-forming systems. Full article

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

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15 pages, 3425 KB

Open AccessArticle

Molecular Dynamics Simulation of the Interfacial Characteristics of Functionalized Carbon Nanotube-Polyimide Composites

by Youyun Zou, Yi Liu, Xin Zha, Ang Wang, Zongrong Wang and Jin Qian

Polymers 2026, 18(13), 1673; https://doi.org/10.3390/polym18131673 - 6 Jul 2026

Viewed by 480

Abstract

Insufficient interfacial interaction between nanoconductive materials and polymer matrices severely limits the mechanical, electrical, and pressure-sensing properties. Carbon nanotubes (CNTs), widely used as polymer reinforcements due to their excellent properties, can significantly enhance the mechanical performance of nanocomposites by improving the interfacial interactions [...] Read more.

Insufficient interfacial interaction between nanoconductive materials and polymer matrices severely limits the mechanical, electrical, and pressure-sensing properties. Carbon nanotubes (CNTs), widely used as polymer reinforcements due to their excellent properties, can significantly enhance the mechanical performance of nanocomposites by improving the interfacial interactions with the matrix. Given the diversity of functionalized CNTs, a systematic study of their interfacial bonding mechanisms is of great importance for both scientific research and engineering applications. To this end, this study employs molecular dynamics simulations to investigate the interfacial characteristics and mechanical responses of functionalized CNT/polyimide (PI) systems. The results demonstrate that functionalization treatments significantly enhance both the interfacial interaction and the shear performance of CNT/PI nanocomposites. Specifically, the interfacial shear strength of the carboxylated CNT/PI composite reaches 269.83 MPa, representing a 20% improvement; furthermore, this property further increases with higher functional group content. This work elucidates the influence of functional group type and content on the interfacial shear performance of CNT/PI composites at the atomic scale, providing new physical insights. Full article

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

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22 pages, 2931 KB

Open AccessReview

Recent Advances and Sustainability Perspectives of Biobased Wood Panel Adhesives: Toward Cleaner and Formaldehyde-Free Wood Products

by Sogand Ghafari Movahed, Iman Rezvani, Ali Dorieh, Saeed Kamrani, Meysam Mehdinia, Mohammadreza Pourpilehkesh, Mohammad Hassan Shahavi, Sara Nabipoor, Petar Antov, Viktor Savov, Viktoria Dudeva, Widya Fatriasari, Lee Seng Hua and Antonio Pizzi

Polymers 2026, 18(13), 1672; https://doi.org/10.3390/polym18131672 - 6 Jul 2026

Cited by 1 | Viewed by 724

Abstract

Biobased wood adhesives are essential to reducing the dependence of wood-based panels on petrochemical and formaldehyde-emitting resins. This review critically synthesizes recent progress in lignin-, tannin-, starch-, furan/HMF-, organic acid-, and soy protein-based adhesive systems, with emphasis on chemical reactivity, curing mechanisms, water [...] Read more.

Biobased wood adhesives are essential to reducing the dependence of wood-based panels on petrochemical and formaldehyde-emitting resins. This review critically synthesizes recent progress in lignin-, tannin-, starch-, furan/HMF-, organic acid-, and soy protein-based adhesive systems, with emphasis on chemical reactivity, curing mechanisms, water resistance, processability, and industrial relevance. The discussion distinguishes laboratory performance from industrial feasibility by considering specific press time, solids content, viscosity, raw material variability, emissions, cost, life-cycle performance, and compatibility with particleboard, medium-density fibreboard, plywood, and related engineered wood products. Lignin and tannins are highlighted as the most chemically compatible phenolic platforms, starch and soy systems as abundant but moisture-sensitive binders requiring targeted crosslinking, HMF and furan derivatives as promising aldehyde-type formaldehyde-free crosslinkers, and citric acid systems as attractive polyester-forming binders with pressing-temperature limitations. The review concludes that near-term adoption will most likely proceed through hybrid and partially biobased systems, whereas fully biobased adhesives require faster curing, standardized feedstocks, pilot-scale validation, and transparent techno-economic and life-cycle assessment. Full article

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

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18 pages, 7245 KB

Open AccessArticle

Cold-Resistance Plasticizers Derived from Bio-Based Trans-Aconitic Acid with High Performance on Solvent Extraction Resistance and Volatility Resistance

by Yirui Shen, Xiaomei Wang, Yangyang Xiong, Xinmeng He, Pingping Jiang and Guizhen Xing

Polymers 2026, 18(13), 1671; https://doi.org/10.3390/polym18131671 - 6 Jul 2026

Viewed by 461

Abstract

Dioctyl adipate (DOA) and dioctyl sebacate (DOS) are widely used cold-resistance plasticizers; however, their low molecular weight and weak polarity result in poor thermal stability and migration resistance. Here, we report the synthesis and performance of bio-based cold-resistance plasticizers derived from trans-aconitic [...] Read more.

Dioctyl adipate (DOA) and dioctyl sebacate (DOS) are widely used cold-resistance plasticizers; however, their low molecular weight and weak polarity result in poor thermal stability and migration resistance. Here, we report the synthesis and performance of bio-based cold-resistance plasticizers derived from trans-aconitic acid with enhanced migration resistance. Tri-n-butyl trans-aconitate (TBTA), tri-n-hexyl trans-aconitate (THTA), and tri-n-octyl trans-aconitate (TOTA) were synthesized via one-step esterification with aliphatic alcohols and applied in poly(vinyl chloride) (PVC). Compared with commercial plasticizers di-(2-ethylhexyl) phthalate (DEHP), tributyl citrate (TBC) and DOA, the synthesized plasticizers demonstrated excellent thermal stability and cold-resistance. After freezing treatment, the

T_{g}

values of TBTA/PVC (18.99 °C) and THTA/PVC (20.88 °C) were lower than those of DEHP/PVC (22.74 °C). The branched architecture was supposed to strengthen interactions between plasticizers and PVC, improving volatility resistance and solvent extraction resistance. Compared with DOA/PVC at 48 h, TBTA/PVC, THTA/PVC and TOTA/PVC displayed volatility mass loss reduction of ~1.5%, 4% and 7%, respectively. Their extraction mass loss in ethanol decreased by 5–6%, while in petroleum ether, TBTA/PVC and TOTA/PVC dropped by 11.95% and 2.63%, respectively. These bio-based plasticizers are promising alternatives to the poor migration resistance of conventional low-temperature plasticizers. Full article

(This article belongs to the Section Polymer Chemistry)

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20 pages, 2090 KB

Open AccessArticle

Operational Domains Governing Melt Flow Index Variability in Industrial Polypropylene Production

by Joaquín Hernández-Fernández and Juan López-Martínez

Polymers 2026, 18(13), 1670; https://doi.org/10.3390/polym18131670 - 6 Jul 2026

Viewed by 335

Abstract

Maintaining a stable melt flow index (MFI) is a critical objective in industrial polypropylene production because MFI directly reflects polymer molecular weight and strongly influences downstream processing performance. Although the effects of catalyst formulation and hydrogen concentration on polypropylene properties are well established, [...] Read more.

Maintaining a stable melt flow index (MFI) is a critical objective in industrial polypropylene production because MFI directly reflects polymer molecular weight and strongly influences downstream processing performance. Although the effects of catalyst formulation and hydrogen concentration on polypropylene properties are well established, the operational origins of residual fluctuations in MFI under highly stable industrial conditions remain poorly understood. In this work, the relationships between feedstock quality, process operation, and residual MFI variability were investigated during the production of a commercial polypropylene grade in an industrial gas-phase reactor. A dataset comprising 61 industrial observations was assembled by integrating laboratory quality measurements with operational variables related to hydrogen concentration, catalyst management, reactor hydrodynamics, thermal behavior, productivity, and fouling. In parallel, the concentrations of key catalyst inhibitors, including carbon oxides, sulfur compounds, water, oxygen, acetylene, methylacetylene, propadiene, arsine, and phosphine, were quantified before and after the use of a modified zeolite-based purification system. The purification process reduced catalyst poisons to ppb levels, producing polymer-grade propylene with monomer purity exceeding 99.95 wt.%. Under these highly controlled conditions, the production campaign exhibited remarkable quality stability, with an average MFI of 3.03 g/10 min and a coefficient of variation of only 6.63%. Principal component analysis revealed that two dominant operational domains could describe 86.49% of the total process variability. The first domain was associated with reactor hydrodynamics, fouling behavior, and thermal conditions, whereas the second domain was governed by catalyst-system variables and hydrogen-mediated chain-transfer mechanisms. Variable importance in projection analysis identified Plate Fouling Factor (VIP = 2.17), Production Rate (VIP = 1.33), and H₂/C₃ Ratio (VIP = 1.17) as the variables most strongly associated with residual MFI fluctuations. The results demonstrate that once feedstock-related disturbances are effectively minimized, residual MFI variability arises from interactions among the hydrodynamic, thermal, and catalytic operational domains rather than from a single controlling parameter. These findings provide new insights into process–quality relationships in industrial polypropylene manufacturing and establish a practical framework for identifying the operational origins of subtle fluctuations in polymer quality in highly stabilized production systems. Full article

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

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21 pages, 9727 KB

Open AccessArticle

Efficient Binary Solution Adsorption Using Polyurethane Foam Composites Integrated with Zr-MOF and Milled Activated Carbon

by Supanicha Alapol, Thidarat Imyen, Khemmathin Lueangwattanapong, Nutchapon Chiarasumran, Maythee Saisriyoot, Anusith Thanapimmetha, Yi-Shen Huang, Chih-Feng Huang and Penjit Srinophakun

Polymers 2026, 18(13), 1669; https://doi.org/10.3390/polym18131669 - 6 Jul 2026

Viewed by 468

Abstract

Wastewater containing heavy metals and dyes poses serious environmental risks. This study developed a multifunctional composite by coating polyurethane foam (PUF) with milled activated carbon (mAC) and a zirconium-based metal–organic framework (Zr-MOF) for the simultaneous removal of hexavalent chromium (Cr(VI)) and Congo red [...] Read more.

Wastewater containing heavy metals and dyes poses serious environmental risks. This study developed a multifunctional composite by coating polyurethane foam (PUF) with milled activated carbon (mAC) and a zirconium-based metal–organic framework (Zr-MOF) for the simultaneous removal of hexavalent chromium (Cr(VI)) and Congo red (CR). The composite was synthesized using a hydrothermal method to grow Zr-MOF on the surface. The SEM analysis confirmed the successful incorporation of mAC and surface modification with Zr-MOF, which resulted in increased surface roughness and porous morphology. XRD and FTIR confirmed the presence of organic ligands connected to the metal structure and the functional groups of each component in composite materials. The optimum conditions for Zr-MOF/mAC/PUF adsorption (nearly 100% removal) in the binary Cr(VI)/CR solution (50 mg/L each) were 25 °C, pH 9, and 150 rpm for 24 h. The Zr-MOF/mAC/PUF was hydrophilic with a swelling ratio of 2.64 g/g. The thermodynamic investigation of Zr-MOF/mAC/PUF resulted in 141.6218 kJ/mol for Cr(VI) and 166.111 kJ/mol for CR of ΔH° (rapid adsorption), negative ΔG° (spontaneous adsorption), a high positive value of ΔS° (disorder structure) and low activation energy (approximately 2.5 to 2.8 kJ/mol). After analyzing the isotherm and reaction kinetics, the possible mechanism could be endothermic physicochemical adsorption and pseudo-second-order kinetic behavior, with electrostatic attraction and diffusion control. The study of 6-times-reused Zr-MOF/mAC/PUF adsorption identified as a decrease of 7.55 percentage point without changing notable morphology and functional groups, based on SEM and FTIR. Full article

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

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37 pages, 2197 KB

Open AccessReview

A Critical Review of Research on the Production and Properties of Chitosan Nanoparticles, Promising for Agrobiotechnology, Obtained Through Ionic Gelation with Sodium Tripolyphosphate

by Sergei L. Shmakov, Natalia N. Pozdnyakova, Oksana V. Tkachenko and Anna B. Shipovskaya

Polymers 2026, 18(13), 1668; https://doi.org/10.3390/polym18131668 - 6 Jul 2026

Viewed by 752

Abstract

Nanoparticles of the aminopolysaccharide chitosan (ChNPs) are effective delivery platforms for biologically active substances for agrobiotechnological applications and hold great promise for solving precision problems in sustainable and efficient agriculture. This review presents an analysis of research publications during the past 20 years [...] Read more.

Nanoparticles of the aminopolysaccharide chitosan (ChNPs) are effective delivery platforms for biologically active substances for agrobiotechnological applications and hold great promise for solving precision problems in sustainable and efficient agriculture. This review presents an analysis of research publications during the past 20 years examining methods for producing ChNPs through ionotropic gelation using sodium tripolyphosphate for cross-linking macrochains, which are of practical interest for agriculture. Key aspects of the nanostructure formation process are analyzed, including the influence of the physicochemical characteristics of the aminopolysaccharide, the concentration and ratio of reagents, and ionic cross-linking conditions on the average size, size distribution (polydispersity), and zeta potential of nanoparticles. Particular attention is paid to several approaches proposed in the literature for determining optimal gelation conditions to obtain ChNPs with pre-specified size characteristics. Potential applications of nanostructured preparations based on these nanoparticles for agrobiochemical purposes are considered, including the encapsulation of antifungal, antiviral and antimicrobial agents, pesticides, NPK fertilizers, metal ions, plant extracts, essential oils, etc., to develop biodegradable stimulants for seed germination and plant growth, increased crop yields, and improved agricultural product quality. It is concluded that blocking the protonated amino groups of chitosan with tripolyphosphate anions is undesirable due to the reduced biological activity of the macromolecules and the nanostructured preparations obtained therefrom. An alternative approach for producing ChNPs with high biological activity with neither use of cross-linking agents nor encapsulation of agrochemicals is described. Full article

(This article belongs to the Special Issue Progress in Preparations and Applications of Chitin and Chitosan)

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24 pages, 3738 KB

Open AccessReview

Poly(methyl vinyl ether-alt-maleic anhydride) and Its Derivatives: From Polymer Synthesis to Advanced Biomedical Applications

by Pedro Valentín Badía-Hernández, Rocío Díaz-Puertas, Paula del Carmen Sánchez-García, Alberto Falcó, Pilar García-Morales and Ricardo Mallavia

Polymers 2026, 18(13), 1667; https://doi.org/10.3390/polym18131667 - 6 Jul 2026

Viewed by 556

Abstract

Poly(methyl vinyl ether-alt-maleic anhydride) (PMVEMA) is a versatile synthetic copolymer that has gained considerable attention in biomedical and pharmaceutical applications due to its biocompatibility, biodegradability, bioadhesive properties and chemical reactivity. This review summarizes the current knowledge regarding the derivatives, physicochemical properties, [...] Read more.

Poly(methyl vinyl ether-alt-maleic anhydride) (PMVEMA) is a versatile synthetic copolymer that has gained considerable attention in biomedical and pharmaceutical applications due to its biocompatibility, biodegradability, bioadhesive properties and chemical reactivity. This review summarizes the current knowledge regarding the derivatives, physicochemical properties, functionalization and crosslinking strategies of PMVEMA, with particular emphasis on their relevance to biomedical applications. A comprehensive literature analysis was performed using major scientific databases, combined with artificial intelligence-assisted text mining, to identify the principal research trends associated with PMVEMA. The reviewed studies demonstrate that the reactive anhydride groups of PMVEMA enable the formation of a wide variety of derivatives, including hydrogels, nanoparticles and nanofibers with tunable properties. These characteristics have facilitated its application in different fields, including immunology, drug delivery, dentistry and dermatology. In particular, PMVEMA-based systems exhibit enhanced mucosal adhesion, controlled drug release, immunoadjuvant activity and biocompatibility in vitro and in vivo. Despite its broad applicability, further studies are still needed to fully elucidate its biodegradation mechanisms in vivo and optimize its clinical translation. Full article

(This article belongs to the Special Issue Polymers in Tissue Regeneration and Antimicrobial Strategies: Innovations and Applications)

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15 pages, 37201 KB

Open AccessArticle

Re-Investigation on Periodic Assembly in Crystallized Poly(ethylene adipate) by Dissecting into Internal Architecture

by Chi-Hsuan Su, Selveraj Nagarajan, Chean-Cheng Su and Eamor M. Woo

Polymers 2026, 18(13), 1666; https://doi.org/10.3390/polym18131666 - 6 Jul 2026

Viewed by 511

Abstract

Through microscopy analyses onto 3D-dissected interiors of crystallized poly(ethylene adipate) (PEA) at isothermal 28 °C temperatures that are known to pack with double ring-banded spherulites, complete surface-relief patterns correlating with interior periodic assembly profiles on mechanisms are obtained. Top-surface-relief ridge bands exhibit different [...] Read more.

Through microscopy analyses onto 3D-dissected interiors of crystallized poly(ethylene adipate) (PEA) at isothermal 28 °C temperatures that are known to pack with double ring-banded spherulites, complete surface-relief patterns correlating with interior periodic assembly profiles on mechanisms are obtained. Top-surface-relief ridge bands exhibit different width caused by slant angles between the interior radially orientated lamellae with respect to the top surface. The detailed interior structures gained from analyses on the dissected PEA spherulites yield critical correlations between the interior assembly and topology banding patterns, leading to a clue that analyses cannot be restricted to simply just on the top-surface-relief patterns. With advanced dissection techniques, 3D views on bulk interiors have offered dramatic breakthrough views and led to unique clarity in assembly mechanisms of periodic crystal aggregation. Full article

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

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20 pages, 6296 KB

Open AccessArticle

Design and Development of High-Performance Bio-Based Thermoplastic Polyurethane (TPU) Nanocomposites Enabled by Silane-Modified Nanocellulose

by Nello Russo, Federica Recupido, Loredana Tammaro, Maria Oliviero, Barbara Liguori, Roberta Marzella, Letizia Verdolotti and Giuseppe Cesare Lama

Polymers 2026, 18(13), 1665; https://doi.org/10.3390/polym18131665 - 5 Jul 2026

Viewed by 537

Abstract

The food packaging sector widely relies on polymeric materials, and as sustainability concerns grow, commodity polymers need to be replaced with innovative and more sustainable materials. Thermoplastic polyurethane (TPU) is a versatile elastomeric polymer characterized by flexibility, strength, chemical and abrasion resistance, and [...] Read more.

The food packaging sector widely relies on polymeric materials, and as sustainability concerns grow, commodity polymers need to be replaced with innovative and more sustainable materials. Thermoplastic polyurethane (TPU) is a versatile elastomeric polymer characterized by flexibility, strength, chemical and abrasion resistance, and biocompatibility. However, it presents some limitations, notably in terms of functional properties (i.e., barrier properties). The use of nano-sized renewable fillers, such as cellulose nanocrystals (CNCs), may improve these properties, extending the applicability range of TPU. In this work, bio-based TPU nanocomposites were obtained by adding commercial silane-modified cellulose nanocrystals (Si−O−CNC) at different contents (1–5 wt.%). The nanocomposites were produced via melt mixing followed by compression molding and were characterized in terms of chemical (FTIR), morphological, thermal, mechanical, rheological, wettability, and barrier properties (i.e., water vapor permeability, WVP and oxygen transmission rate, OTR). The presence of Si−O−CNC promoted hydrogen bonding interactions with the TPU matrix, affecting the microphase separation and organization of the hard segments. These microstructural changes improved thermal stability, reduced WVP and OTR, and increased tensile properties at lower nanofiller contents (1–3 wt.%). At higher contents, partial nanofiller aggregation was observed, leading to a reduction in mechanical performance. Overall, these results suggest that TPU/Si−O−CNC nanocomposites have promising potential as sustainable food packaging materials. Full article

(This article belongs to the Special Issue Advances in Hybrid Polymer Nanocomposites)

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22 pages, 5819 KB

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Printability, Mechanical Response, and Surface Integrity of MEX-Manufactured Gyroid Lattices with Uniform and Graded Cell Sizes

by Ray Tahir Mushtaq, Ghulam Hassan Askari, Mudassar Rehman, Rakan Albarakati, Yanen Wang and Aqib Mashood Khan

Polymers 2026, 18(13), 1664; https://doi.org/10.3390/polym18131664 - 4 Jul 2026

Viewed by 533

Abstract

Triply periodic minimal surface (TPMS) gyroid lattices are promising lightweight and energy-absorbing polymer structures, but their manufacturability by material extrusion (MEX) depends strongly on cell size, grading direction, and relative density. This study investigates PLA gyroid lattices with uniform and graded cell-size configurations [...] Read more.

Triply periodic minimal surface (TPMS) gyroid lattices are promising lightweight and energy-absorbing polymer structures, but their manufacturability by material extrusion (MEX) depends strongly on cell size, grading direction, and relative density. This study investigates PLA gyroid lattices with uniform and graded cell-size configurations using initial and final cell sizes of 1, 1.5, and 2 mm and target relative densities of 10, 20, and 30%. A full-factorial design was used to construct a printability map, followed by quasi-static compression testing, areal surface-roughness characterization, and SEM observation of representative specimens. The printability results showed that low-density fine-cell configurations were most prone to incomplete wall formation and collapse, whereas the 30% relative-density group was printable for all investigated cell-size combinations. Under compression, the 30% relative-density uniform 1 mm gyroid showed the highest maximum stress among the tested configurations, while graded structures terminating in smaller cells also provided favorable load bearing and energy-absorption behavior. The plateau stability index, calculated from stress fluctuations between collapse and densification, helped distinguish stable progressive collapse from more oscillatory deformation. Surface roughness and SEM observations further indicated that smoother, more continuous wall surfaces were associated with more uniform deformation, whereas rougher and defect-rich surfaces promoted localized buckling, cracking, and brittle collapse. Overall, the results identify experimentally supported relationships between gyroid cell-size configuration, printability, surface integrity, and compressive response within the investigated PLA MEX design space. Full article

(This article belongs to the Special Issue 3D/4D Printing of Polymers: Recent Advances and Applications)

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35 pages, 50354 KB

Open AccessArticle

A Multi-Physics Modeling Framework for Optimizing Spreading and Sintering Parameters in Powder Bed Fusion

by Jiang Li, Fulun Peng, Jianzhao Zhao, Xinliang Chai, Junjie Fu, Shaoying Li and Xujiang Chao

Polymers 2026, 18(13), 1663; https://doi.org/10.3390/polym18131663 - 4 Jul 2026

Viewed by 448

Abstract

Powder Bed Fusion-Laser Beam/Polymer (PBF-LB/P) is a key additive manufacturing technology widely used in aerospace, but its process parameters are difficult to optimize for thermoplastic composites due to poor powder flowability and unstable melting regions. To address this challenge, this paper develops discrete [...] Read more.

Powder Bed Fusion-Laser Beam/Polymer (PBF-LB/P) is a key additive manufacturing technology widely used in aerospace, but its process parameters are difficult to optimize for thermoplastic composites due to poor powder flowability and unstable melting regions. To address this challenge, this paper develops discrete element and finite element models to systematically determine the PBF process window for both powder spreading and sintering stages, with verified reliability. In the spreading stage, the powder layer performance is evaluated through surface profile, density, and uniformity. The effects of reinforcement phase, spreading speed, and layer thickness are analyzed, establishing reasonable spreading parameter windows. It is found that the optimal layer thickness for PEEK powder is determined to be 0.13 mm, while that for PEEK/CF composite powder is 0.12 mm. At the optimal layer thickness, the powder bed exhibits desirable properties, which minimize its adverse influence on the sintering process and serve as a prerequisite for subsequently establishing the sintering process window. For the sintering stage, sufficient sintering constraint criteria are established, and a systematic determination method is proposed. By analyzing microscopic sintering mechanisms and characterizing the effects of laser power, scanning speed, and hatching space on melt pool dimensions and temperature, a reasonable sintering process window can be efficiently determined. It is found that within the process window, the PEEK specimens achieved a maximum relative density of 99.31% and exhibited a tensile strength 13.1% higher than that of specimens processed outside the window, demonstrating a clear superiority. Full article

(This article belongs to the Special Issue Research on Additive Manufacturing of Polymer Composites, 2nd Edition)

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19 pages, 34988 KB

Open AccessArticle

Organo-Montmorillonite (OMMT) Modified SiC/Hydrogenated Epoxy Micro–Nanocomposites for Enhanced Corona Aging Resistance

by Haitao Hu, Hailiang Dong, Mingpeng He, Boxin Ma, Yanli Liu and Junguo Gao

Polymers 2026, 18(13), 1662; https://doi.org/10.3390/polym18131662 - 4 Jul 2026

Viewed by 550

Abstract

The concentration of electric fields at the end region of stator bars in large generators can readily induce corona discharge. Under long-term operation, corona discharge may cause drift in the surface conductivity and nonlinear coefficient of anti-corona materials, thereby weakening their capability to [...] Read more.

The concentration of electric fields at the end region of stator bars in large generators can readily induce corona discharge. Under long-term operation, corona discharge may cause drift in the surface conductivity and nonlinear coefficient of anti-corona materials, thereby weakening their capability to homogenize the tangential electric field. In severe cases, this can lead to charring failure of the anti-corona material. To improve the electrical-parameter stability and surface morphological resistance to corona aging of silicon carbide (SiC)-based anti-corona materials under long-term corona exposure, epoxy-resin-based anti-corona materials were investigated in this study. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were first employed to analyze the effects of corona aging on the microstructure and chemical structure of the anti-corona layer, thereby revealing its failure mechanism. Subsequently, the evolution of surface conductivity, nonlinear coefficient, and surface morphology of bisphenol A epoxy resin (EP)- and hydrogenated bisphenol A epoxy resin (H-EP)-based anti-corona materials during 120 h of corona aging was comparatively investigated. On this basis, different mass fractions of organically modified montmorillonite (OMMT) were introduced into the H-EP-based anti-corona material for synergistic modification. The OMMT used in this study had a particle size of approximately 5 μm and an interlayer spacing of 2.6 nm, and its lamellar morphology and dispersion state in the epoxy matrix were characterized by cross-sectional SEM. Meanwhile, the trap-regulation mechanism of the OMMT-modified anti-corona materials was analyzed using isothermal surface potential decay (ISPD). The results show that erosion of the epoxy resin matrix by corona discharge is the primary cause of internal conductive-pathway disruption and anti-corona layer failure. Compared with the EP-based material, the H-EP-based material exhibited better conductivity and nonlinear stability during aging, although a certain degree of drift still occurred. The incorporation of an appropriate amount of OMMT further improved the corona resistance of the material. Among the investigated samples, the material containing 1 wt% OMMT showed the best performance, with its conductivity stabilized within the range of 10⁻¹³–10⁻¹¹ S, the lowest variation rate of 104.76%, a relatively stable nonlinear coefficient, and slight surface damage. The ISPD results indicate that the interfaces introduced by OMMT increase the deep-trap density and suppress carrier migration, thereby stabilizing the conductive network. Overall, the synergistic effect of the H-EP matrix and 1 wt% OMMT can effectively enhance the corona resistance of SiC-based anti-corona materials. Full article

(This article belongs to the Special Issue Aging Behavior and Durability of Polymer Materials, 2nd Edition)

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18 pages, 4045 KB

Open AccessArticle

Prediction of the Young’s Modulus of Polylactic Acid Specimens Manufactured by Fused Deposition Modeling Using Machine Learning-Based Stacking Ensemble Methods

by Alexandru Constantin Stanciu, Anton Hadăr, Nicolae Goga, Mihai-Constantin Butolo, Florin Baciu, Stefan-Dan Pastrama and Daniel Vlăsceanu

Polymers 2026, 18(13), 1661; https://doi.org/10.3390/polym18131661 - 4 Jul 2026

Viewed by 502

Abstract

In this paper, a machine learning model to predict the Young’s modulus of polylactic acid specimens manufactured by Fused Deposition Modeling is proposed, based on a stacked ensemble architecture. The model uses as input parameters the fill degree, printing speed, filling pattern, yield [...] Read more.

In this paper, a machine learning model to predict the Young’s modulus of polylactic acid specimens manufactured by Fused Deposition Modeling is proposed, based on a stacked ensemble architecture. The model uses as input parameters the fill degree, printing speed, filling pattern, yield strength, and tensile strength, along with additional features obtained through feature engineering. The proposed approach integrates nine base models with a linear meta-model, allowing it to capture both linear and nonlinear relationships between the variables. The results obtained on the test dataset show strong predictive performance, with a Mean Squared Error with a value of 7.31 together with a Coefficient of Determination R² with a value of 0.99, which is noticeably better than the performance of the individual models. To validate the model, a separate group of specimens was tested, and the difference between the measured and predicted Young’s modulus was about 1% on average. The model was also implemented in a desktop application with a graphical interface, in which the calculation can be run directly, thus allowing a rapid estimation of Young’s modulus. In this way, the need for laborious experimental testing is reduced with the help of AI-based approaches in additive manufacturing. Full article

(This article belongs to the Section Artificial Intelligence in Polymer Science)

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17 pages, 3045 KB

Open AccessArticle

3D Printing of Block Copolymer-Based Fracture Tough Denture Base Materials

by Kai Rist, Iris Lamparth, Sadini Omeragic, Lauren Geurds, Benjamin Grob and Yohann Catel

Polymers 2026, 18(13), 1660; https://doi.org/10.3390/polym18131660 - 4 Jul 2026

Viewed by 417

Abstract

The development of 3D printing high-impact denture bases is challenging, as materials exhibiting both high flexural strength/modulus and fracture toughness are required. Nowadays, most of the commercially available 3D printing denture bases contain significant amounts of crosslinking monomers and therefore behave as brittle [...] Read more.

The development of 3D printing high-impact denture bases is challenging, as materials exhibiting both high flexural strength/modulus and fracture toughness are required. Nowadays, most of the commercially available 3D printing denture bases contain significant amounts of crosslinking monomers and therefore behave as brittle materials. In this contribution, urethane dimethacrylate DMA1/(octahydro-4,7-methano-1H-indenyl)methyl acrylate (OMIMA) 1/1 (wt/wt) formulations containing a poly(ε-caprolactone)-polydimethylsiloxane-poly(ε-caprolactone) (PCL-PDMS-PCL) triblock copolymer (BCP1) and fumed silica SiO₂-NPs were evaluated for DLP 3D printing of fracture-tough denture bases. The post-curing step was performed at various temperatures (RT, 60 °C, 80 °C, 100 °C and 120 °C). This parameter was shown to strongly influence the T_g and mechanical properties of 3D printed materials. A post-curing temperature of 100 °C was found to be ideal. Under these conditions, 3D printed materials exhibiting excellent mechanical properties were successfully obtained. Furthermore, the amounts of BCP1 and SiO₂-NPs were varied. The formulation containing 8.0 wt% of BCP1 and 10.0 wt% of SiO₂-NPs (FS = 67.5 ± 1.3 MPa, FM = 2450 ± 71 MPa, K_max = 2.11 ± 0.06 MPa m^1/2, W_f = 1109 ± 19 J m⁻²) was able to fulfill the ISO 20795-1:2013 requirements in terms of flexural strength (FS)/modulus (FM) and fracture toughness for denture bases with improved impact resistance (FS > 65 MPa, FM > 2000 MPa, K_max > 1.9 MPa m^1/2, W_f > 900 J m⁻²). This material showed better performance than the commercially available formulations Printodent^® GR-14.2 denture HI (FS = 69.2 ± 1.8 MPa, FM = 2153 ± 76 MPa, K_max = 0.82 ± 0.04 MPa m^1/2, W_f = 79 ± 10 J m⁻²) and Lucitone Digital Print^TM 3D denture base (FS = 56.7 ± 1.9 MPa, FM = 2144 ± 12 MPa, K_max = 1.92 ± 0.09 MPa m^1/2, W_f = 1272 ± 177 J m⁻²). Full article

(This article belongs to the Special Issue Polymeric Materials and Their Application in 3D Printing, 3rd Edition)

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21 pages, 16920 KB

Open AccessArticle

Acid-Based Deep Eutectic Solvents for Structural Modification of Sulphite Pulp Cellulose: A Potential Route Toward Advanced Materials

by María Guadalupe Morán-Aguilar, Iván Costa-Trigo, José Manuel Domínguez and Fabiola Vilaseca

Polymers 2026, 18(13), 1659; https://doi.org/10.3390/polym18131659 - 3 Jul 2026

Viewed by 548

Abstract

The transition toward renewable and environmentally responsible materials has intensified interest in cellulose-based systems for use in sustainable packaging applications. Although cellulose offers biocompatibility, structural versatility, and tuneable physicochemical properties, conventional modification routes rely on harsh chemicals and generate environmentally burdensome effluents. In [...] Read more.

The transition toward renewable and environmentally responsible materials has intensified interest in cellulose-based systems for use in sustainable packaging applications. Although cellulose offers biocompatibility, structural versatility, and tuneable physicochemical properties, conventional modification routes rely on harsh chemicals and generate environmentally burdensome effluents. In this study, an efficient and a potentially green strategy for cellulose modification was developed using acid-based deep eutectic solvents (DES) composed of choline chloride and lactic, acetic, or citric acid at different molar ratios. Under mild conditions (110 °C, 4 h), DES pretreatment reduced glucan content in sulphite pulp from 99% to 79–93%, depending on the hydrogen bond donor (HBD), while suggesting an apparent increase in relative crystallinity, from approximately 82% to 90%, as estimated by the Segal method. FTIR, XRD, and morphological analyses revealed the disruption of the hydrogen bonding network, enhanced fibrillation, and residual DES-derived functional groups detectable by FTIR. Although DES pretreatment increased structural order, it also reduced enzymatic digestibility due to the higher proportion of crystalline domains. Overall, the results demonstrate that acidic DES constitutes a sustainable and recyclable medium capable of modulating cellulose structure and generating materials with enhanced physicochemical properties. These findings suggest that DES-modified cellulose could serve as a potential reinforcement platform for future biodegradable packaging and bioplastic formulations, enabling the development of high-performance, renewable, and environmentally compliant packaging materials. Full article

(This article belongs to the Special Issue Green Innovation in the Processing of Cellulose Derived Polymers)

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26 pages, 1870 KB

Open AccessArticle

Evaluation of Surface Impact Properties of Thermoplastics: Mechanical Correlation Between Critical Expansion Stress and Uniaxial Tensile Strength

by Tetsuo Takayama, Koki Tsuchiya and Akito Endo

Polymers 2026, 18(13), 1658; https://doi.org/10.3390/polym18131658 - 3 Jul 2026

Viewed by 583

Abstract

For the impact-resistance evaluation of thermoplastics, the DuPont impact test is widely used to replicate multiaxial stress states inherent in actual product environments. However, conventional evaluation methods remain constrained by probabilistic pass/fail judgments or empirical calculations of absorbed energy. Consequently, quantifying the “material-specific [...] Read more.

For the impact-resistance evaluation of thermoplastics, the DuPont impact test is widely used to replicate multiaxial stress states inherent in actual product environments. However, conventional evaluation methods remain constrained by probabilistic pass/fail judgments or empirical calculations of absorbed energy. Consequently, quantifying the “material-specific fracture criterion,” which is indispensable for high-fidelity computer-aided engineering (CAE) analysis, persists as an important challenge. While our previous works established the derivation of CES from uniaxial tensile tests, the core originality of this study lies in extending this mechanical framework to the dynamic and multiaxial stress states of the DuPont impact test. By integrating a mathematical model with the probabilistic results of the staircase method, we enable for the first time the quantitative identification of material-specific fracture thresholds directly from standard drop-weight impact configurations. For this study, a novel mechanical model for deformation and fracture behavior in the DuPont impact test is constructed. Then a quantitative evaluation method is proposed for the “Critical Expansion Stress (CES),” a material-specific threshold triggering fracture under multiaxial stress. Specifically, using thermoplastic materials of five types and seven grades (including PP, POM, PS, ABS, and PC), the surface impact energy absorbed per unit volume was calculated via the DuPont impact test using the staircase method, accounting for size effects. Furthermore, microscopic parameters (shear modulus G and critical void volume fraction f0) were identified theoretically based on the mechanical properties obtained from short-beam shear tests. These parameters were integrated into a mathematical model to derive the CES. Comparing the derived CES with the true-stress-based uniaxial tensile strength, which incorporates the necking behavior during large deformations, revealed a distinct correlation governed by their mechanical relation (the 1:3 rule) based on the theoretical definition of hydrostatic stress. For the highly ductile polymer exhibiting significant strain hardening, this correlation holds universally when evaluated at the initial plastic flow stage prior to massive molecular orientation. The proposed method serves as a practical quantitative screening tool for evaluating the surface impact characteristics of plastic materials, providing an accessible framework for identifying material-specific fracture thresholds. Full article

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

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23 pages, 6191 KB

Open AccessArticle

Performance of ASA Polymer-Modified Asphalt Mixtures Under Aging Conditions

by Khalifa Salem Gallouz, Shaban Ismael Albrka Ali, Amina B. Abubakar, Faridah Hanim Khairuddin, Munder Bilema, Nasradeen Ali Khalifa and Mustafa Alas

Polymers 2026, 18(13), 1657; https://doi.org/10.3390/polym18131657 - 3 Jul 2026

Viewed by 552

Abstract

The effects of weather conditions on modified asphalt mixtures were investigated in this study. Acrylonitrile Styrene Acrylate (ASA) polymer was used as a modifier with concentrations of 3, 5, and 7%. The viscosity test was performed to determine the blending and compaction temperatures [...] Read more.

The effects of weather conditions on modified asphalt mixtures were investigated in this study. Acrylonitrile Styrene Acrylate (ASA) polymer was used as a modifier with concentrations of 3, 5, and 7%. The viscosity test was performed to determine the blending and compaction temperatures for the base and modified mixtures, while Field Emission Scanning Electron Microscopy (FE-SEM) was utilized to explore the dispersion of the polymer in the asphalt binder matrix. Moreover, mechanical tests were applied to observe the changes in the modified asphalt binders. The highest improvements were obtained for a 5% ASA concentration. The resilient modulus increased by 78%, while resistance to dynamic creep improved by 74% compared with the base asphalt mixture. The wheel tracking and moisture susceptibility results further illustrated that the modified asphalt mixtures were less susceptible to moisture than the base asphalt mixture. The aging index results showed that the modifier can mitigate the effects of weather conditions, and the 5% ASA showed the best performance among the mixtures. Full article

(This article belongs to the Special Issue Advances in Polymers and Polymer Composites for Construction)

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26 pages, 1933 KB

Open AccessArticle

Holistic Approach for the Comparative Assessment of Chemical Structure and Functional Properties of Major Categories of Agricultural Plastics

by Sarai Agustin Salazar, Paolo Maria Riccobene, Sabrina Carola Carroccio, Fabiana Convertino, Antonis Mistriotis, Christina Pyromali, Andrea Antonino Scamporrino, Evelia Schettini, Giuliano Vox and Pierfrancesco Cerruti

Polymers 2026, 18(13), 1656; https://doi.org/10.3390/polym18131656 - 3 Jul 2026

Viewed by 497

Abstract

This study evaluates the performance of major types of conventional and bio-based plastic items commonly used in agriculture to provide comprehensive insights into their key structural and functional properties, including the chemical composition of the polymer matrix and additives, mechanical behavior, and thermal [...] Read more.

This study evaluates the performance of major types of conventional and bio-based plastic items commonly used in agriculture to provide comprehensive insights into their key structural and functional properties, including the chemical composition of the polymer matrix and additives, mechanical behavior, and thermal and radiometric properties. Twelve agricultural plastic (AP) items were analyzed: covering mulch films, geotextile ground cover, protection fleece and low tunnel fleece cover, fertilizer sack, fly trap, irrigation pipe, tree binding net, guide for tree, silage film and hay bales protection fabric. This selection of APs also encompasses a broad range of basic polymers, including conventional materials (mainly polyethylene and polypropylene) and bio-based formulations (primarily starch- or lignocellulose-containing blends). Mass spectrometry and infrared spectroscopy analyses were performed to assess polymer composition and additives. Mechanical properties were assessed through tensile and puncture tests; in addition, radiometric, thermogravimetric, surface wettability, water absorption and permeability tests were also performed to assess other relevant physical characteristics. The study identified significant differences among bio-based biodegradable APs and compared them with their conventional polyolefin-based counterparts. Material composition and structure were found to critically influence water interactions, shaping the balance between durability, degradation, and crop protection performance. Notably, bio-based mulch films exhibited higher water vapor permeability (0.6–1.1 × 10⁻¹³ g/m Pa s), reduced penetration resistance (12.1 N) and lowered impact and tensile strengths (21.8 MPa). Water interaction tests showed that the starch-based mulch film displayed very high swelling (above 100%), favoring biodegradation, whereas a biodegradable blend based on polyhydroxybutyrate and polybutylene succinate exhibited minimal swelling (<3%). Material composition and morphology were also key determinants of water vapor transport: dense polymer films provided superior moisture barriers (permeability range 0.013–0.04 × 10⁻¹³ g/m Pa s), while fibrous or biodegradable materials allowed enhanced vapor permeability. The results of this study, highlighting functionality, advantages and limitations of biodegradable APs versus conventional APs, are intended to guide future innovation in AP design, ensuring alignment with both the operational demands of modern agriculture and environmental sustainability goals. The data obtained from this study can support scientific advancements and policy recommendations on the use and management of plastics in agriculture. Full article

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

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23 pages, 7306 KB

Open AccessArticle

Development and Characterization of Andrographolide Microparticles via Spray Drying: An Aqueous-Based Chitosan/Cellulose/Poloxamer Carrier Approach

by Nuttapong Khiaonoi, Kwanchai Kraitong, Punyawan Lumpaopong and Jarupa Viyoch

Polymers 2026, 18(13), 1655; https://doi.org/10.3390/polym18131655 - 3 Jul 2026

Viewed by 539

Abstract

Andrographolide-loaded microparticles with an aqueous-based carrier system were developed with the aim of pulmonary drug delivery. Five formulations of andrographolide (0.6–5.8% w/w) loaded on mixed-polymer carriers containing chitosan (CHS), hydroxyethyl cellulose (HEC), Poloxamer 188, and PEG 20,000, with various ratios [...] Read more.

Andrographolide-loaded microparticles with an aqueous-based carrier system were developed with the aim of pulmonary drug delivery. Five formulations of andrographolide (0.6–5.8% w/w) loaded on mixed-polymer carriers containing chitosan (CHS), hydroxyethyl cellulose (HEC), Poloxamer 188, and PEG 20,000, with various ratios were produced under various spray-drying parameters: solution viscosity (5–20 cP), atomization air pressure (0.8–1.5 bar) and solution feed rate (3–6 mL/min). The physiochemical properties of the microparticles were strongly affected by carrier composition and atomization air pressure. The optimal formulation: andrographolide 0.6% w/w, CHS 62.2% w/w, HEC 15.5% w/w and Poloxamer 188 21.7% w/w, spray dried using solution viscosity 15 cP, atomization air pressure 1.1 bar and feed rate 3 mL/min, was selected according to its particle sizes (3–5 µm) with rough morphology, encapsulation efficiency (54.47%) and release behaviors (22.31%/h and 89.23% within 4 h). Good physical, chemical, and thermal stabilities under room storage condition (28 ± 2 °C, 50% relative humidity) were also proven. Importantly, it demonstrated potent antiviral activity against Influenza A/H1N1, achieving a 3.3-log₁₀ reduction in viral titer with 99.95% inhibition. Overall, this aqueous-based carrier approach and spray-drying technique offer a stable and effective inhalable formulation for localized treatment of influenza infections. Full article

(This article belongs to the Special Issue Functional Polymer Applications in Drug Delivery and Tissue Engineering)

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14 pages, 17578 KB

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Mechanical-Enhanced Porous Silk-Based Cryogenic Microneedles for Cell Thawing/Revival in the Gastric Wall

by Zhiwei Yin, Limin Zhang, Rui Shi, Xin Xia, Zhaoxin Wang, Ling Li and Zhuo Chen

Polymers 2026, 18(13), 1654; https://doi.org/10.3390/polym18131654 - 3 Jul 2026

Viewed by 512

Abstract

Cell therapies for gastric disorders lack minimally invasive delivery platforms that preserve cell viability during storage and enable effective tissue penetration, owing to the high toughness and harsh environment of the gastric wall. Herein, we developed a mechanically reinforced, porous silk-based cryogenic microneedle [...] Read more.

Cell therapies for gastric disorders lack minimally invasive delivery platforms that preserve cell viability during storage and enable effective tissue penetration, owing to the high toughness and harsh environment of the gastric wall. Herein, we developed a mechanically reinforced, porous silk-based cryogenic microneedle (silk-cryoMN) platform for in situ cell delivery to the gastric wall. The optimized 1.5% (w/v) silk scaffolds exhibited interconnected pores (24.4 ± 7.9 μm, ~81% porosity), a compressive strength (422.8 ± 73.4 MPa), and a 3.4-fold increase in β-sheet content. The silk-cryoMNs showed greater thermal stability than H₂O-cryoMNs, maintaining structural integrity for over 60 s at room temperature. With a cryopreservation medium containing 100 mM sucrose and 2% DMSO, post-thaw cell viability exceeded 80% after 11 days of freezing, and most cells were released within 1 h. Furthermore, ex vivo studies confirmed penetration of porcine gastric tissue to depths of 422–448 μm within 30 s. These results suggest that the platform may address several translational barriers, including tissue penetration, handling stability, and cell viability preservation. Further in vivo studies and long-term safety evaluations are needed before clinical translation can be considered. Full article

(This article belongs to the Special Issue Advances in Cellular Polymeric Materials)

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18 pages, 9938 KB

Open AccessArticle

Comparing the Properties of Cellulose Nitrates Synthesized from Miscanthus × giganteus Stems and from Commercial Microcrystalline Cellulose

by Vera V. Budaeva, Anna A. Korchagina, Yulia A. Gismatulina, Evgenia K. Gladysheva, Polina A. Gorbatova, Anastasia A. Zenkova, Vladimir N. Zolotukhin and Gennady V. Sakovich

Polymers 2026, 18(13), 1653; https://doi.org/10.3390/polym18131653 - 2 Jul 2026

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Abstract

This paper reports new results on the synthesis and comparative characterization of cellulose nitrates (CNs) derived from Miscanthus × giganteus stems and from commercial microcrystalline cellulose (MCC). Miscanthus CNs synthesized by nitration with mixed sulfuric–nitric acids containing 16–20% water exhibit new functional properties: [...] Read more.

This paper reports new results on the synthesis and comparative characterization of cellulose nitrates (CNs) derived from Miscanthus × giganteus stems and from commercial microcrystalline cellulose (MCC). Miscanthus CNs synthesized by nitration with mixed sulfuric–nitric acids containing 16–20% water exhibit new functional properties: a high solubility in organic solvents (100% in acetone and 97–99% in alcohol–ether solvent) and a high viscosity (17–51 mPa·s), with a nitrogen content of 10.54–12.08 wt%. CNs from Miscanthus × giganteus are similar in nitrogen content and solubility to those from MCC (11.54% and 99%) but have a significantly greater viscosity (3 mPa·s), which is an undoubted advantage and considerably expands their potential application range. The solubility test of CNs synthesized from both sources demonstrated that Miscanthus CNs have a better film-forming ability. SEM analysis revealed a great difference in fiber length, despite the same cylindrical shape and observed aggregation: 1.0–2.0 mm for CNs from Miscanthus versus 40–60 μm for CNs from MCC. IR spectra of CNs from both sources showed the appearance of five new characteristic frequencies (1632–1633, 1273–1274, 823–826, 748, 677–686 cm^–1 for Miscanthus CNs and 1659, 1277, 832, 747, 691 cm^–1 for CNs from MCC), allowing the obtained compounds to be identified as nitric acid esters of cellulose. According to TGA/DTA analysis, the synthesized polymers have similarly high values of the onset temperature of both intense decomposition (197–198 °C) and narrow exothermic peaks (209–211 °C and 212 °C), respectively, indicating their high thermal stability. The combination of high solubility, viscosity, thermal stability and chemical purity of CNs derived from Miscanthus × giganteus stems suggests that strong thin films can be obtained and recommended for use in the manufacture of nitrocellulose membranes. Full article

(This article belongs to the Special Issue Cellulose and Its Composites: Preparation and Applications)

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27 pages, 5089 KB

Open AccessReview

Toward Predictive Design of Lignocellulosic Mycelium-Bound Composites: A Process–Structure–Property Framework, Quantitative Synthesis, and Standardization Roadmap

by Musiliu A. Liadi, Tawakalt O. Ayodele, Ibrahim A. Bello, C. Igathinathane and Hammed M. Ademola

Polymers 2026, 18(13), 1652; https://doi.org/10.3390/polym18131652 - 2 Jul 2026

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Abstract

Mycelium-bound composites (MBCs) have emerged as a promising class of biofabricated materials that integrate fungal hyphal networks with lignocellulosic substrates to form lightweight, biodegradable structures without synthetic adhesives. Despite rapid growth in the field, the current literature remains fragmented, with inconsistent methodologies and [...] Read more.

Mycelium-bound composites (MBCs) have emerged as a promising class of biofabricated materials that integrate fungal hyphal networks with lignocellulosic substrates to form lightweight, biodegradable structures without synthetic adhesives. Despite rapid growth in the field, the current literature remains fragmented, with inconsistent methodologies and widely varying reported material properties. This review advances the field by moving beyond descriptive synthesis toward a quantitative and conceptual integration of existing studies. We systematically analyze how key fabrication variables—including fungal species, substrate composition, growth conditions, and post-processing parameters—govern density, porosity, and mechanical performance. A process–structure–property (PSP) framework is proposed to combine these relationships and explain discrepancies across studies. We highlight the dominant role of densification and moisture conditioning in determining compressive strength, often outweighing species-level effects. A comparative synthesis of reported data reveals significant variability in compressive strength (0.05–1.2 MPa) and elastic modulus, attributable to inconsistencies in sample preparation, testing protocols, and environmental conditioning. To address this, we identify critical gaps in standardization and propose actionable testing protocols and reporting guidelines for reproducibility. Furthermore, we assess the technology readiness level (TRL) of MBC systems and distinguish between laboratory-scale innovations and commercially viable processes. While hybridization strategies and biofunctional applications offer promising avenues, their maturity varies widely. This work provides a decision-oriented framework for MBC design and a roadmap for transitioning these materials from experimental systems to scalable, standardized, and application-ready biomaterials. Full article

(This article belongs to the Special Issue Advanced Study on Lignin-Containing Composites)

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26 pages, 13392 KB

Open AccessArticle

Influence of Cryogenic Cyclic Aging on Room-Temperature Mechanical and Tribological Performance of Polyimide-Based Materials

by Maksim Nikonovich, Amilcar Ramalho and Nazanin Emami

Polymers 2026, 18(13), 1651; https://doi.org/10.3390/polym18131651 - 2 Jul 2026

Viewed by 534

Abstract

Cryogenic environments impose severe thermal and mechanical stresses on polymer components, yet the effects of long-term cryogenic cycling on their subsequent room-temperature performance remain insufficiently understood. This study investigated the influence of cryogenic cyclic aging on the mechanical and tribological behaviour of polyimide [...] Read more.

Cryogenic environments impose severe thermal and mechanical stresses on polymer components, yet the effects of long-term cryogenic cycling on their subsequent room-temperature performance remain insufficiently understood. This study investigated the influence of cryogenic cyclic aging on the mechanical and tribological behaviour of polyimide (PI)-based materials, including neat PI and composites reinforced with MoS₂, graphite, and/or PTFE. Repeated cryogenic cycling was followed by mechanical characterisation and tribological testing at 25 °C in air and vacuum. This work systematically compares neat and filled PI materials after cryogenic cyclic aging and correlates mechanical changes with transfer-film formation and wear behaviour. Cryogenic cyclic aging had only minor effects on weight and thermal stability but significantly altered the viscoelastic behaviour, increasing creep and residual strain, with variations depending on the polymer structure and filler content. Fracture toughness showed a statistically significant improvement only for PI2 (up to 93%). Changes in PI1, PI3, PI4, and PI5 fell within the experimental scatter and were interpreted as non-significant trends. In air, abrasive wear dominated in unreinforced PI, while graphite/PI composites exhibited adhesive wear and improved transfer film formation, reducing wear rates by up to 26%. In vacuum, the wear rate of aged graphite/PI increased by up to two orders of magnitude. Full article

(This article belongs to the Special Issue Advances in High-Performance Polyimides: Preparation, Characterization and Application)

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Polymers, Volume 18, Issue 13 (July-1 2026) – 125 articles

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