Polymers

12 pages, 8471 KB

Open AccessArticle

Adhesion of Composite Resin to Additively Manufactured Zirconia Using a Self-Adhesive Resin Cement: Evaluation of Micro-Shear Bond Strength

by Yue Zhu and Chao Qian

Polymers 2026, 18(18), 2305; https://doi.org/10.3390/polym18182305 (registering DOI) - 20 Sep 2026

Abstract

Effective bonding between zirconia ceramic restorations and resin remains a clinical challenge, particularly in the context of intraoral repair and cementation. This study aimed to investigate the micro-shear bond strength (μSBS) of stereolithography (SLA)- and digital light processing (DLP)-fabricated zirconia–resin cement-composite resin bonding [...] Read more.

Effective bonding between zirconia ceramic restorations and resin remains a clinical challenge, particularly in the context of intraoral repair and cementation. This study aimed to investigate the micro-shear bond strength (μSBS) of stereolithography (SLA)- and digital light processing (DLP)-fabricated zirconia–resin cement-composite resin bonding specimens. Rectangular zirconia specimens (10 × 5 × 5 mm³) were fabricated by SLA, DLP, and computer numerical control (CNC) milling technologies. The surface roughness (Ra) of zirconia was measured after air abrasion. A composite resin cylinder (5 mm in height and 1 mm in diameter) was added to each zirconia substrate for the μSBS test. The failure mode images were obtained using a scanning electron microscope. The adhesive, cohesive, and mixed failure patterns were analyzed. The Ra and μSBS values were statistically analyzed with one-way ANOVA followed by S-N-K post hoc comparisons (a = 0.05). The Ra of SLA (1.05 ± 0.03 μm) and DLP (1.02 ± 0.03 μm) zirconia after air-abrasion were significantly higher than that of CNC (0.91 ± 0.02 μm) (p < 0.001). The SLA (23.37 ± 4.66 MPa) and DLP (23.24 ± 3.7 MPa) groups exhibited similar μSBS values for the bonding specimens to those of the CNC group (21.13 ± 3.48 MPa) (p = 0.237), indicating that the bond strength of the zirconia–resin cement-composite resin assembly for SLA and DLP zirconia was comparable to that for CNC zirconia. Full article

(This article belongs to the Section Polymer Applications)

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54 pages, 6131 KB

Open AccessReview

Polymer Microfiltration and Ultrafiltration Membranes Containing Inorganic Modifiers: Functional Properties and Performance—Review

by Yuliya S. Dzyazko, Valentina V. Chmilenko, Priscila Pini Pereira, Ludmila M. Rozhdestvenska, Katerina O. Kudelko, Nicole Novelli do Nascimento, Angélica Marquetotti Salcedo Vieira, Letícia Nishi and Rosângela Bergamasco

Polymers 2026, 18(18), 2304; https://doi.org/10.3390/polym18182304 (registering DOI) - 20 Sep 2026

Abstract

Modifying MF and UF polymer membranes with hydrophilic compounds is one of the well-known antifouling strategies, which also allows one to achieve a compromise between fluid permeability and the retention of one or another species. Hydrophilizing inorganic substances are widely used for modifying [...] Read more.

Modifying MF and UF polymer membranes with hydrophilic compounds is one of the well-known antifouling strategies, which also allows one to achieve a compromise between fluid permeability and the retention of one or another species. Hydrophilizing inorganic substances are widely used for modifying due to their enhanced chemical stability and multifunctionality. In this review, the inorganic modifiers are categorized according to their effect on organic contaminants and bacteria: (i) non-destructive (natural and synthetic aluminosilicates, phosphates and oxides of multivalent elements, particularly magnetic nanoparticles), (ii) bacteria-destructing (silver nanoparticles, advanced carbon nanomaterials, MXenes), and (iii) strongly destructive, which disrupt both bacteria and organic substances (photocatalysts). The mechanism of antibacterial activity of different modifiers is considered. The main approaches to modifying are stressed: blending polymers with preliminarily formed nanoparticles followed by membrane formation, synthesis of them inside the pores of membranes or on their surface, embedding pre-formed particles into pores, or modifying the surface with them. A comparative analysis of the functional properties and performance of pure polymer membranes and materials containing inorganic modifiers has been conducted. The attention is focused on the ability of modified membranes based on various polymers to retain both macromolecular and low-molecular-weight substances together with high fluid permeability and stability against organic contaminants and biofouling. The limitations of materials containing various types of inorganic modifiers are analyzed. Among the possible directions of further investigations, the development of a universal theoretical approach to modifying is noted; moreover, the testing of the materials has to involve the treatment of real solutions. Full article

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

19 pages, 2542 KB

Open AccessArticle

Bio-Based Brewer’s Spent Grain Particleboards: Effect of Rosin Coating and Wood Veneer Reinforcement on Structure and Properties

by Lucia Rossi, Federico Rueda, Emiliano M. Ciannamea and Pablo M. Stefani

Polymers 2026, 18(18), 2303; https://doi.org/10.3390/polym18182303 (registering DOI) - 20 Sep 2026

Abstract

Brewer’s spent grain (BSG) is an abundant agro-industrial by-product with potential for manufacturing sustainable particleboards, although its relatively low cellulose content limits the mechanical performance of the resulting boards. In this study, particleboards were produced from BSG using a soybean protein concentrate (SPC)-based [...] Read more.

Brewer’s spent grain (BSG) is an abundant agro-industrial by-product with potential for manufacturing sustainable particleboards, although its relatively low cellulose content limits the mechanical performance of the resulting boards. In this study, particleboards were produced from BSG using a soybean protein concentrate (SPC)-based adhesive at three adhesive contents. In addition, rosin surface coating and wood veneer reinforcement were investigated as strategies to improve the performance of the boards. Physical and mechanical properties were evaluated according to American and European standards, while X-ray micro-computed tomography was used to analyze the structure of the panels. Increasing the SPC content significantly improved all mechanical and physical properties. Rosin coating further reduced water absorption and moisture diffusivity while improving the modulus of rupture, modulus of elasticity, and internal bond strength. X-ray micro-CT analysis revealed local density increases associated with rosin penetration into the board structure. The greatest improvement was achieved with wood veneer reinforcement particleboards, satisfying the H1-ANSI A208.1 and P2-EN312 minimum flexural requirements. Moreover, Digital Image Correlation (DIC) revealed that wood veneer reinforcement significantly altered the deformation and failure mechanisms. These results demonstrate that simple surface reinforcement strategies enable the production of bio-based particleboards with significantly improved performance. Full article

(This article belongs to the Special Issue Cellulose and Wood-Based Materials in Polymer Systems and Materials Engineering)

20 pages, 4363 KB

Open AccessArticle

Semi-Analytical Large-Strain Bending of Thermoviscoplastic SMP Beams with Plastic Softening

by Hamed Khashabi, Majid Baniassadi, Eunsoo Choi and Mostafa Baghani

Polymers 2026, 18(18), 2302; https://doi.org/10.3390/polym18182302 (registering DOI) - 20 Sep 2026

Abstract

The accurate prediction of the large-strain thermomechanical response of shape memory polymer (SMP) beams is challenging because geometric nonlinearities must be coupled with temperature-dependent viscoelastic and viscoplastic mechanisms, including plastic softening. This study develops a semi-analytical framework for the large-strain pure bending of [...] Read more.

The accurate prediction of the large-strain thermomechanical response of shape memory polymer (SMP) beams is challenging because geometric nonlinearities must be coupled with temperature-dependent viscoelastic and viscoplastic mechanisms, including plastic softening. This study develops a semi-analytical framework for the large-strain pure bending of thermoviscoplastic SMP beams. The formulation combines finite-deformation bending kinematics with the thermoviscoplastic constitutive model of Zeng et al., while a mapping-based fitting strategy is introduced to approximate the through-thickness distribution of the viscous mechanical stretches. The resulting stress field is obtained by enforcing radial equilibrium in polar coordinates and satisfying the traction-free inner and outer surfaces. The formulation is implemented in MATLAB R2026a and independently verified against a three-dimensional ABAQUS/Explicit model incorporating the same constitutive equations through a user-defined VUMAT. Shape recovery, bending-force recovery, stress distributions, deformation fields, and mesh sensitivity are investigated for two SMP material parameter sets. The semi-analytical and finite element predictions show close agreement throughout the thermomechanical cycles. For example, at the end of the relaxation stage, the predicted inner radii are 27.27 mm and 27.26 mm for the semi-analytical and finite element approaches, respectively, corresponding to a difference of approximately 0.04%. The results demonstrate that the proposed formulation provides an efficient alternative for analyzing large-strain SMP bending while retaining the essential path-dependent thermoviscoplastic behavior. Full article

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

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14 pages, 6832 KB

Open AccessArticle

Elastic Response of Open-Hole Material-Extruded PLA Plates: Equivalent Laminate Architectures and Perimeter Paths

by Mehmet Emin Baysal and Yasin Uslugil

Polymers 2026, 18(18), 2301; https://doi.org/10.3390/polym18182301 (registering DOI) - 20 Sep 2026

Abstract

The elastic response of an open-hole material-extruded plate depends on both its interior raster architecture and the deposition paths around its boundaries. This study examines whether laminate preferences obtained from a homogeneous model persist when perimeter paths are represented. Six symmetric equivalent-laminate architectures [...] Read more.

The elastic response of an open-hole material-extruded plate depends on both its interior raster architecture and the deposition paths around its boundaries. This study examines whether laminate preferences obtained from a homogeneous model persist when perimeter paths are represented. Six symmetric equivalent-laminate architectures were compared for polylactic acid plates at hole-diameter-to-width ratios of 0.20, 0.25, and 0.40 using plane-stress finite-element models with homogeneous interiors, tangential hole bands, and combined hole and outer bands. Mesh refinement, an independent block mesh, and layered-shell comparisons assessed numerical consistency. In the finest homogeneous comparison at a ratio of 0.25,

[90 / 45 / 90]

reduced the stress concentration factor by 0.90% relative to

[0 / 0 / 0]

, while increasing displacement by approximately 2.84%. Adding hole and outer bands reversed this stress advantage, giving a 1.38% higher stress concentration for

[90 / 45 / 90]

. Across the complete perimeter-model screen,

[0 / 0 / 0]

gave both the lowest stress concentration and the lowest displacement, eliminating the preference-dependent trade-off found in the homogeneous models. Comparison with published tensile curves gave elastic-slope discrepancies of 0.5–3.9% for the primary material dataset and 13.2–16.0% for the experimental source’s constants; this literature-based benchmark is limited to global elastic response and does not validate local hole-edge stresses, failure loads, or laminate ranking. Perimeter paths can therefore determine the preferred elastic architecture even when the interior material exhibits only weak orthotropy. Full article

(This article belongs to the Special Issue Polymer Manufacturing Processes)

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18 pages, 1714 KB

Open AccessArticle

Response Surface Optimization of Cellulose-Rich Material Recovery from Carludovica palmata Fibers: Effects onStructural and Thermal Properties

by Rogelio Antonio Canul Piste, Emilio Pérez Pacheco, Carlos Rolando Ríos Soberanis, Mario Adrián de Atocha Dzul Cervantes, Jorge Carlos Canto Pinto and Alejandro Ortiz Fernández

Polymers 2026, 18(18), 2300; https://doi.org/10.3390/polym18182300 (registering DOI) - 20 Sep 2026

Abstract

This study optimized the chemical treatment conditions for Carludovica palmata fibers using response surface methodology (RSM) based on central composite designs (CCDs). Acid and alkaline treatments were evaluated as independent experimental routes to determine the effects of reagent concentration, temperature, and treatment time [...] Read more.

This study optimized the chemical treatment conditions for Carludovica palmata fibers using response surface methodology (RSM) based on central composite designs (CCDs). Acid and alkaline treatments were evaluated as independent experimental routes to determine the effects of reagent concentration, temperature, and treatment time on gravimetric recovery. The resulting models identified operating conditions associated with maximum predicted recovery within each experimental domain. Maximum experimental gravimetric recoveries of 42.7% and 57.7% were obtained for the acid and alkaline treatments, respectively. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to evaluate structural and thermal changes in the resulting materials. FTIR spectra showed reductions in bands associated with hemicellulose and lignin-related functionalities after chemical treatment. The Segal crystallinity index increased from 41.2% in untreated fibers to 52.7% and 63.8% in the materials obtained under the selected acid and alkaline treatment conditions, respectively. Thermal analysis further showed an increase in the maximum degradation temperature following chemical treatment. Collectively, the results demonstrate that the treatment conditions influenced both gravimetric recovery and the structural and thermal characteristics of the recovered materials. These findings support further investigation of C. palmata as a non-conventional lignocellulosic feedstock for cellulose-based polymer materials. Full article

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

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15 pages, 3687 KB

Open AccessArticle

Influence of Infill Density on Bacterial Colonization and Mechanical Performance of 3D-Printed PETG Scaffolds

by Raghad A. Alabdli, Rewaa S. Jalal, Abdulrahman A. Alqarni, Ahmad A. Basalah and Laila A. Damiati

Polymers 2026, 18(18), 2299; https://doi.org/10.3390/polym18182299 (registering DOI) - 20 Sep 2026

Abstract

Polyethylene terephthalate glycol (PETG) is a versatile thermoplastic widely used in food packaging and biomedical applications owing to its excellent mechanical properties, chemical resistance, biocompatibility, and ease of processing. Porosity is a critical design parameter that governs the biological and mechanical performance of [...] Read more.

Polyethylene terephthalate glycol (PETG) is a versatile thermoplastic widely used in food packaging and biomedical applications owing to its excellent mechanical properties, chemical resistance, biocompatibility, and ease of processing. Porosity is a critical design parameter that governs the biological and mechanical performance of 3D-printed PETG structures by influencing cell attachment, nutrient transport, mechanical integrity, and microbial interactions. In this study, PETG scaffolds were fabricated at five nominal infill densities (20%, 40%, 60%, 80%, and 100%) using fused deposition modelling (FDM) to investigate the influence of printing-defined architecture on mechanical performance and bacterial colonization. Tensile testing revealed that decreasing infill density resulted in a progressive reduction in ultimate tensile strength and Young’s modulus, demonstrating the trade-off between reduced material density and mechanical integrity. Bacterial interactions with the scaffolds were evaluated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Salmonella typhimurium using optical density (OD) and ATP-based viability assays to quantify both planktonic and adherent bacterial populations. The results demonstrated that the influence of scaffold porosity was species-dependent. The results demonstrated species-dependent responses to scaffold architecture. Higher infill densities were generally associated with reduced attachment and metabolic activity for P. aeruginosa, S. epidermidis, and S. typhimurium, whereas E. coli exhibited relatively stable growth and metabolic activity across the tested infill conditions. S. aureus showed an intermediate response, with bacterial attachment and metabolic activity varying according to scaffold architecture. Overall, infill density exerted a greater influence on scaffold-associated bacteria than on planktonic populations, while simultaneously determining the mechanical performance of the printed structures. These findings demonstrate that controlling PETG infill architecture is important for balancing mechanical properties and bacterial colonization and provide design insights for future PETG-based biomedical and food-packaging applications. Full article

(This article belongs to the Special Issue Advanced Polymer Processing for Tissue Engineering)

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26 pages, 7243 KB

Open AccessReview

Ultrasound-Assisted Deep Eutectic Solvent Extraction of Polysaccharides: Mechanistic Foundations, Structural Consequences, and Process Optimization

by Kit-Leong Cheong, Si Xu, Wanzi Yao, Farwa Abdul Hafeez, Amanullah Sabir, Afifa Aziz, Zhanhui Cao and Udayakumar Veerabagu

Polymers 2026, 18(18), 2298; https://doi.org/10.3390/polym18182298 (registering DOI) - 20 Sep 2026

Abstract

Ultrasound-assisted deep eutectic solvent (DES) extraction has emerged as a promising green and intensified strategy for recovering natural polysaccharides from plant, algal, fungal, and other biological matrices. By coupling acoustic cavitation with tunable solvent microenvironments, this approach can enhance cell-wall disruption, solvent penetration, [...] Read more.

Ultrasound-assisted deep eutectic solvent (DES) extraction has emerged as a promising green and intensified strategy for recovering natural polysaccharides from plant, algal, fungal, and other biological matrices. By coupling acoustic cavitation with tunable solvent microenvironments, this approach can enhance cell-wall disruption, solvent penetration, mass transfer, and polysaccharide solubilization while reducing reliance on harsh acidic, alkaline, or organic solvents. However, extraction efficiency alone is insufficient to define process quality because ultrasound-assisted DES systems may also reshape the molecular weight distribution, monosaccharide composition, uronic acid or sulfate content, substitution pattern, charge density, conformation, surface morphology, and physicochemical behavior. These structural consequences directly influence downstream bioactivities, including antioxidant, hypoglycemic, prebiotic, anti-inflammatory, and anti-ulcerative colitis effects. This review critically summarizes the mechanistic foundations of ultrasound–DES synergy, analyzes how extraction conditions determine polysaccharide structural outcomes, and highlights the importance of linking structure with functionality. Emerging data-driven approaches, including solvent prescreening, COSMO-RS, and machine learning-assisted process optimization, are also discussed as supporting tools for navigating the multidimensional extraction space. However, their current application to the direct prediction of polysaccharide structural outcomes remains limited. Future progress will require standardized datasets, advanced structural characterization, causal structure–activity validation, and scalable process engineering. Overall, ultrasound-assisted DES extraction should be viewed as a structure-sensitive extraction platform whose performance depends on the coordinated control of solvent properties, acoustic conditions, biomass characteristics, and downstream processing. Full article

(This article belongs to the Special Issue Lignin and Polysaccharide Derived Functional Polymers for Sustainable Applications)

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25 pages, 46994 KB

Open AccessArticle

Toughening PLA via Diisocyanate-Induced Dynamic Vulcanization of Carboxylated Oleic Acid: Role of Crosslinked Network Topology

by Dongmei Xie, Xiao Li, Jiaqi Cai, Xiaodi Mao, Hongzhi Liu and Ping Zhang

Polymers 2026, 18(18), 2297; https://doi.org/10.3390/polym18182297 (registering DOI) - 19 Sep 2026

Abstract

Diisocyanate-induced dynamic vulcanization of difunctional fatty acids has emerged as a universal strategy to efficiently improve the impact resistance of polylactic acid (PLA). However, how the crosslinked network topology of the in situ formed polyamide elastomer (COPA) affects its toughening efficacy on PLA [...] Read more.

Diisocyanate-induced dynamic vulcanization of difunctional fatty acids has emerged as a universal strategy to efficiently improve the impact resistance of polylactic acid (PLA). However, how the crosslinked network topology of the in situ formed polyamide elastomer (COPA) affects its toughening efficacy on PLA remains unknown. Here, we synthesized two carboxylated fatty acids with distinct molecular architectures (TCOA and NCOA) from technical-grade and high-purity oleic acids via UV-initiated thiol-ene click chemistry. These two diacids, along with tetradecanedioic acid (TA) without a dangling chain, were dynamically vulcanized with hexamethylene diisocyanate (HDI) to toughen PLA. By varying NCO/COOH molar ratios between HDI and TCOA, their effects on gel content, crosslinking density, phase morphology, and mechanical properties of resulting blends were systematically investigated. With increasing the ratio, both gel content and interfacial adhesion with PLA in the blends were enhanced, accompanied by the transformation of phase structure from “sea-island” morphology to a partially or fully co-continuous one. At a molar ratio of 1.8:1, the notched impact strength value of the blend reached 86.5 kJ/m². By substituting TCOA with high-purity NCOA or TA, comparable gel content and interfacial compatibilization level, and co-continuous morphologies were achieved. Notably, NCOA yielded a PLA blend with a remarkably higher impact toughness (131.0 kJ/m²). The linear chain structure of TA led to a higher crosslinking density of the formed TAPA domains, which unfavorably suppressed their cavitation during impact fracture and thus resulted in an inferior impact strength (7.0 kJ/m²). These findings provide valuable insights into the toughening mechanism of PLA via dynamic vulcanization of monomers. Full article

(This article belongs to the Special Issue Advanced Poly(lactic Acid) Materials and PLA-Based Composites: From Fundamentals to Applications)

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31 pages, 19465 KB

Open AccessArticle

Sulfation of Sugarcane-Bagasse Xylan: Process Optimization, Physicochemical Properties and In Vitro Anticoagulant Activity

by Mingjun Zhang, Xuefeng Wang, Qi Wang and Jianbin Li

Polymers 2026, 18(18), 2296; https://doi.org/10.3390/polym18182296 (registering DOI) - 19 Sep 2026

Abstract

Xylan sulfates are established anticoagulant polysaccharides, but their preparation requires balancing sulfate substitution and product recovery. Sugarcane-bagasse xylan was sulfated using sulfur trioxide–pyridine complex (SO₃·Py), 4-dimethylaminopyridine (DMAP), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI). An entropy-weighted five-factor Box–Behnken design jointly optimized degree of [...] Read more.

Xylan sulfates are established anticoagulant polysaccharides, but their preparation requires balancing sulfate substitution and product recovery. Sugarcane-bagasse xylan was sulfated using sulfur trioxide–pyridine complex (SO₃·Py), 4-dimethylaminopyridine (DMAP), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDCI). An entropy-weighted five-factor Box–Behnken design jointly optimized degree of substitution (DS) and isolated, DS-adjusted yield, assigning respective weights of 0.570 and 0.430. Pareto analysis identified a trade-off between increasing DS and decreasing yield, while accounting for model uncertainty produced little change in the selected optimum. Validation used adjusted reagent-to-xylan mass ratios of 0.2, 3.2, and 2.2 g/g for DMAP, SO₃·Py, and EDCI, respectively, at 50.7 °C for 3.8 h. Three independent batches yielded DS = 1.53 ± 0.01, yield = 78.0 ± 0.1%, and a composite score of 0.792 ± 0.008, within the model’s 95% prediction interval. Operational water solubility increased from 21.2 to 96.8–130.4 mg/mL after sulfation, alongside changes in aqueous aggregation and rheology. In citrated sheep plasma, the derivatives prolonged activated partial thromboplastin time and thrombin time with increasing concentration. Responses increased across the derivative series, in which DS and the reported apparent molar mass covaried. These results provide a basis for balancing substitution and product recovery and comparing the water solubility and in vitro anticoagulant responses of the resulting derivatives. Full article

(This article belongs to the Section Polymer Chemistry)

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23 pages, 9739 KB

Open AccessArticle

Influence of Functional Additives with Potential Antimicrobial Properties on the Mechanical Performance and Accelerated Aging Resistance of (Meth)Acrylate-Based Composites

by Karolina Kiełczewska-Klim, Andrzej Puszka, Magdalena Jaszek and Beata Podkościelna

Polymers 2026, 18(18), 2295; https://doi.org/10.3390/polym18182295 (registering DOI) - 19 Sep 2026

Abstract

The main aim of this study was to prepare and evaluate the physicochemical properties of new composite materials based on bisphenol A dimethacrylate modified with selected comonomers, namely 2-ethylhexyl acrylate (AEH), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and N-vinylpyrrolidone (NVP), and additives with [...] Read more.

The main aim of this study was to prepare and evaluate the physicochemical properties of new composite materials based on bisphenol A dimethacrylate modified with selected comonomers, namely 2-ethylhexyl acrylate (AEH), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and N-vinylpyrrolidone (NVP), and additives with potential antimicrobial properties, including nanosilver (Ag), copper(II) sulfate (CuSO₄), benzethonium chloride (BEN), zinc oxide (ZnO), and zinc methacrylate (metZnO). The resulting composites were evaluated for their mechanical, structural, and ageing-related properties. The results demonstrated that the type of comonomer significantly influenced material performance. The lowest swelling coefficients were observed in composites containing AEH, whereas the highest values were observed in NVP-based materials. All investigated composites exhibited high hardness values. Accelerated ageing resulted in a reduction in hardness for all materials. Dynamic Mechanical Analysis (DMA) revealed that the highest glass transition temperatures were obtained for materials containing NVP and HEMA, particularly those modified with metZnO. Fourier Transform Infrared Spectroscopy (FTIR) confirmed that the chemical structure of the composites remained unchanged after accelerated ageing. Furthermore, colour changes were observed after ageing, with the most pronounced effects found for composites containing CuSO₄ and BEN. The obtained results confirm that the appropriate selection of a comonomer and a modifying additive effectively enhances the beneficial properties of composite materials with special features. Full article

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

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18 pages, 10781 KB

Open AccessArticle

Alizarin Red S-Functionalized Polyurethane Coatings as Passive Colorimetric Interfaces for Visual Heavy-Metal Screening in Simulated Seawater

by Silvia Sfameni, Mariam Hadhri, Giulia Rando, Agnese D’Agostino, Raphael Palucci Rosa, Giuseppe Rosace, Valentina Trovato and Maria Rosaria Plutino

Polymers 2026, 18(18), 2294; https://doi.org/10.3390/polym18182294 (registering DOI) - 19 Sep 2026

Abstract

This study investigates Alizarin Red S (ARS)-functionalized polyurethane (PU) coatings as passive colorimetric interfaces for preliminary visual screening of selected heavy-metal ions in simulated seawater. ARS was incorporated into a hydrophilic PU matrix and deposited on glass substrates. UV–visible spectroscopy and ATR-FTIR were [...] Read more.

This study investigates Alizarin Red S (ARS)-functionalized polyurethane (PU) coatings as passive colorimetric interfaces for preliminary visual screening of selected heavy-metal ions in simulated seawater. ARS was incorporated into a hydrophilic PU matrix and deposited on glass substrates. UV–visible spectroscopy and ATR-FTIR were used to analyze the optical and vibrational features of the PU–ARS system, while DLS provided comparative information on the colloidal behavior of the liquid precursor formulations before film formation. After 48 h exposure to simulated seawater (ASTM D1141-98, pH 8.2) containing Pb²⁺, Cd²⁺, Ni²⁺, or Hg²⁺ at 5 × 10⁻⁴ M, the coatings developed ion-dependent color changes quantified in the CIE L*a*b* color space. Under these single-ion conditions, the total color difference followed the order Pb²⁺ > Cd²⁺ > Ni²⁺ > Hg²⁺, with approximate ΔE values of 27, 19, 16, and 13, respectively. Saline pre-immersion experiments up to 72 h, followed by 48 h exposure to metal-ion solutions, indicated that the coatings retained macroscopic readability and optical responsiveness under the tested conditions. The results support the use of PU–ARS coatings as proof-of-concept passive interfaces for visual heavy-metal screening in marine-like media. Further studies including calibration, detection limits, selectivity, interference, leaching assessment, and validation in real seawater will be required before analytical implementation. Full article

(This article belongs to the Section Polymer Applications)

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34 pages, 7234 KB

Open AccessArticle

Waste-Tea-Leaf-Derived Microcrystalline Cellulose as a Reinforcement for FDM-Printed PLA: Extraction, Filament Fabrication, Mechanical Performance, and Acoustic Absorption

by Prabhu Cikkuraj, Gokulkumar Sivanantham and Bhuvaneswari Venkateswaran

Polymers 2026, 18(18), 2293; https://doi.org/10.3390/polym18182293 (registering DOI) - 19 Sep 2026

Abstract

Upcycling agro-industrial residues into functional reinforcements supports the circular economy while addressing the brittleness and limited stiffness of poly(lactic acid) (PLA) in fused deposition modeling (FDM). In this study, industrial waste tea leaves were converted into microcrystalline cellulose (WTL-MCC) and used to produce [...] Read more.

Upcycling agro-industrial residues into functional reinforcements supports the circular economy while addressing the brittleness and limited stiffness of poly(lactic acid) (PLA) in fused deposition modeling (FDM). In this study, industrial waste tea leaves were converted into microcrystalline cellulose (WTL-MCC) and used to produce multifunctional PLA composite filaments. WTL-MCC was extracted by dewaxing, alkali treatment, bleaching, and mild acid hydrolysis and characterized by FTIR, XRD, TGA–DTG, DSC, UV–Vis, BET, SEM–EDAX, and AFM. It showed a crystallinity index of 48%, a crystallite size of 2.8 nm and thermal stability to 250 °C (T_max = 322 °C). Filaments containing 1, 3, 5, and 7 wt.% WTL-MCC were extruded (1.75 ± 0.05 mm; >97% yield) and printed into ASTM specimens for mechanical (D638/D790/D695) and acoustic (E1050) testing. The properties peaked at 3 wt.% WTL-MCC; beyond this loading, strength declined owing to particle agglomeration and aligned inter-raster voids, confirmed by fractography. The optimized PLA/3MCC composite exhibited mid-to-high-frequency sound absorption (α_max = 0.76 at 4000 Hz; NRC 0.385) arising from micro-voids and cellulose surface roughness. Waste-tea-derived MCC, therefore, yields dimensionally consistent printable PLA filaments and multifunctional printed parts, combining an enhanced load-bearing capacity with useful acoustic damping, with 3 wt.% identified as the optimum loading. Full article

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

32 pages, 1114 KB

Open AccessArticle

Batch-to-Flow Translation of β-Cyclodextrin Polymer Adsorption for Emerging Contaminant Removal: Hydrodynamic and Operational Validation

by Antonio Tomás Hernández Cegarra, Teresa Gómez-Morte, José Antonio Pellicer, María Isabel Rodríguez-López, Nuria Vela, Ángel Gil-Izquierdo, Estrella Núñez-Delicado and José Antonio Gabaldón

Polymers 2026, 18(18), 2292; https://doi.org/10.3390/polym18182292 (registering DOI) - 19 Sep 2026

Abstract

Translating adsorption performance from batch experiments to continuous-flow operation is a key step toward practical water-treatment applications. In this study, a laboratory-scale continuous adsorption system based on a water-insoluble β-cyclodextrin-epichlorohydrin (β-CD-EPI) polymer was validated from hydrodynamic, adsorptive, and operational perspectives. Downflow operation caused [...] Read more.

Translating adsorption performance from batch experiments to continuous-flow operation is a key step toward practical water-treatment applications. In this study, a laboratory-scale continuous adsorption system based on a water-insoluble β-cyclodextrin-epichlorohydrin (β-CD-EPI) polymer was validated from hydrodynamic, adsorptive, and operational perspectives. Downflow operation caused progressive bed compaction and excessive pressure development, whereas a 90 mm column operated in upflow mobile-bed mode, with visually observed bed expansion, showed comparatively stable pressure-drop behavior at superficial linear velocities below approximately 12 m h⁻¹. Under these controlled high-loading conditions, removal was strongly contaminant-dependent: cyproconazole exceeded 90%, acetaminophen reached 72–77%, hydrochlorothiazide reached 40–65%, ciprofloxacin reached 24–50%, and furosemide remained below 30%. The relative performance for furosemide and hydrochlorothiazide differed from that predicted by previous batch-derived adsorption parameters, demonstrating that batch results cannot be directly extrapolated to dynamic operation. Competitive adsorption in binary and ternary mixtures reduced contaminant removal, while cyproconazole removal decreased from >90% in tap water to 48–55% in secondary-treated wastewater, demonstrating the relevance of the aqueous matrix under the tested continuous-flow conditions. Operational screening tests showed that desorption with 220 mM acetate buffer at pH 4.0 recovered >80% of the retained cyproconazole within 10 min in the tested sequence, followed by a two-stage rinse that restored the operational pH. These preliminary conditions require confirmation through replicated adsorption–desorption cycles under continuous-flow operation. These results identify laboratory-scale hydrodynamic, adsorption, matrix, and regeneration considerations that require confirmation through fixed-condition, long-term testing during subsequent process development. Full article

(This article belongs to the Section Polymer Applications)

17 pages, 5280 KB

Open AccessArticle

Fabrication of a Flexible PDMS/MWCNTs Composite Sensor Based on a Triboelectric Nanogenerator (Teng) and Its Application in Pulse Monitoring

by Longfei Zhang and Guowei Gao

Polymers 2026, 18(18), 2291; https://doi.org/10.3390/polym18182291 (registering DOI) - 19 Sep 2026

Abstract

In view of the demand for wearable physiological monitoring, porous PDMS/MWCNTs composite films were fabricated via the sacrificial template method in this work. Output performance tests were carried out on films with different sacrificial particle sizes, film thicknesses, and multi-walled carbon nanotube (MWCNT) [...] Read more.

In view of the demand for wearable physiological monitoring, porous PDMS/MWCNTs composite films were fabricated via the sacrificial template method in this work. Output performance tests were carried out on films with different sacrificial particle sizes, film thicknesses, and multi-walled carbon nanotube (MWCNT) mass fractions. Scanning electron microscopy (SEM) was employed for structural morphology characterization. The optimal particle size, thickness, and doping ratio were confirmed to be 63 μm, 3 mm, and 9 wt%, respectively, and flexible sensor arrays based on triboelectric nanogenerators were further fabricated. In this paper, a complete signal conditioning system consisting of a flexible sensor array and a signal acquisition circuit (including a power supply unit, reset circuit, signal conditioning module, and core control chip) was designed to realize data transmission and upper computer display. Pulse signals from four volunteers were collected in five groups, respectively, for comparative analysis. Experimental results reveal that multiple sets of pulse data from the same subject show high consistency. Slight deviations within 0.38 V are merely caused by breathing and other subtle interference factors. These results verify that the prepared sensor possesses favorable sensitivity and repeatability. Full article

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

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19 pages, 12317 KB

Open AccessArticle

Development and Characterization of a Dual Nanofibrillar Membrane of Polylactic Acid Loaded with Hydroxyapatite and Chlorhexidine for Guided Bone Regeneration

by Jose Roberto Sauma, Diego Batista-Menezes, Silvia Maldonado-Frías, Reynaldo Pereira Reyes, Mauricio Montero-Aguilar, Marco Antonio Alvarez-Perez and Daniel Chavarria-Bolanos

Polymers 2026, 18(18), 2290; https://doi.org/10.3390/polym18182290 (registering DOI) - 19 Sep 2026

Abstract

Guided bone regeneration requires membranes that combine structural stability, biocompatibility, and bioactive properties. This study aimed to develop a bilayer electrospun polylactic acid (PLA) membrane incorporating nanohydroxyapatite (nano-HA) and chlorhexidine (CHX). Membranes were fabricated by electrospinning at 15 kV and divided into four [...] Read more.

Guided bone regeneration requires membranes that combine structural stability, biocompatibility, and bioactive properties. This study aimed to develop a bilayer electrospun polylactic acid (PLA) membrane incorporating nanohydroxyapatite (nano-HA) and chlorhexidine (CHX). Membranes were fabricated by electrospinning at 15 kV and divided into four groups: PLA 10% (control), PLA 10%/CHX 0.2%, PLA 10%/nano-HA 10%, and a bilayer combining the CHX- and nano-HA-loaded formulations in separate monolayers, creating a bilayer nanofibrillar scaffold. We characterized microscopic structure, thermal behavior, and chemical composition using scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. We evaluated cellular compatibility through cell adhesion and WST-1 metabolic activity assays. All groups exhibited randomly arranged nanofibrillar networks with comparable fiber morphology, while nano-HA-containing membranes showed particulate agglomerates. Thermal analyses indicated changes associated with material incorporation without evidence of major disruption of the PLA matrix, while chemical analyses confirmed incorporation of nano-HA and CHX. CHX-containing membranes did not compromise cell viability, whereas HA-containing membranes promoted favorable cell distribution and morphology. These findings demonstrate the feasibility of producing bilayer PLA membranes incorporating HA and CHX while maintaining suitable physicochemical characteristics and cellular compatibility. Full article

(This article belongs to the Special Issue Biopolymer-Based Materials in Medical Applications, Second Edition)

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23 pages, 4692 KB

Open AccessArticle

Performance-Based Optimization of Soybean-Based Recycling Agents in SBS-Modified Asphalt Binders and High-RAP

by Anas AbuAlia, Ibrahim Elnaml, Louay N. Mohammad, Samuel B. Cooper III and Gaylon L. Baumgardner

Polymers 2026, 18(18), 2289; https://doi.org/10.3390/polym18182289 (registering DOI) - 19 Sep 2026

Abstract

Asphalt binders are complex viscoelastic polymeric materials whose rheological behavior is governed by interactions among their chemical constituents and, in polymer-modified systems, the morphology and stability of the dispersed polymer network. This study developed a performance-based framework for selecting the type and dosage [...] Read more.

Asphalt binders are complex viscoelastic polymeric materials whose rheological behavior is governed by interactions among their chemical constituents and, in polymer-modified systems, the morphology and stability of the dispersed polymer network. This study developed a performance-based framework for selecting the type and dosage of bio-based soybean recycling agents (RAs) for styrene-butadiene-styrene (SBS)-modified asphalt mixtures containing 30% reclaimed asphalt pavement (RAP). Ten dense-graded asphalt mixtures with a nominal maximum aggregate size of 12.5 mm were evaluated, including a control mixture produced with PG 76-22 (PG 67-22 asphalt binder modified with 3.5% SBS) and no RAP, and nine mixtures containing 30% RAP and three soybean-based recycling agents (RA1, RA2, and RA3) at dosages of 0.5%, 2.0%, and 4.0% by weight of binder. Binder characterization included Superpave performance grading, while mixture performance was evaluated using the Hamburg Wheel Tracking (HWT) test, freeze–thaw-conditioned HWT, Semi-Circular Bend (SCB), IDEAL-CT, IDEAL-RT, and Cantabro abrasion loss tests. Increasing recycling-agent dosage improved cracking resistance but progressively reduced rutting resistance, consistent with the measured decrease in binder viscosity. The magnitude of the softening effect followed the order RA3 > RA2 > RA1, consistent with measured viscosity reductions and HWT rut-depth response. Integrating SCB fracture resistance with the HWT rutting criterion identified acceptable dosage ranges of 1.4–4.0%, 0.5–2.8%, and 0.5–0.7% for RA1, RA2, and RA3, respectively. These results demonstrate that the effectiveness of the evaluated recycling agents, as reflected by binder rheology and asphalt mixture performance, influences the balance between fracture resistance and permanent deformation, providing a performance-based framework for optimizing bio-based recycling-agent selection in high-RAP polymer-modified asphalt mixtures. Full article

(This article belongs to the Special Issue Advancements in Polymeric Material Characterization for Industrial Applications: From Properties to Performance, 2nd Edition)

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20 pages, 9982 KB

Open AccessArticle

Geometry as a Selector of Optical States in Curved Photonic Architectures

by Ion Sandu, Claudiu Teodor Fleaca, Iulia Antohe, Florian Dumitrache, Iuliana Urzica, Iustina Popescu and Marius Dumitru

Polymers 2026, 18(18), 2288; https://doi.org/10.3390/polym18182288 (registering DOI) - 19 Sep 2026

Abstract

Optical response is commonly regarded as an intrinsic property of a photonic structure. Here we show that, in curved photonic systems, geometry plays a dual role: the photonic architecture defines the optical-state landscape, whereas the illumination–observation geometry determines which optical states become experimentally [...] Read more.

Optical response is commonly regarded as an intrinsic property of a photonic structure. Here we show that, in curved photonic systems, geometry plays a dual role: the photonic architecture defines the optical-state landscape, whereas the illumination–observation geometry determines which optical states become experimentally accessible. Self-assembled, millimetre-scale, free-standing curved silica opals coupled to spherical water droplets on Teflon or planar mirrors reveal simultaneous access to multiple Bragg diffraction bands, together with distance-controlled spectral redistribution, spatially organized halos, and pseudo-collimated beams under different illumination–observation geometries. Natural illumination further reveals optical responses relevant to biological and biomimetic photonic structures. Key aspects of this optical functionality are transferred to a graded curved photonic heterostructure formed by partial polystyrene infiltration of a curved silica opal, demonstrating that the underlying geometrical principle extends beyond liquid-confined systems. Curved photonic architectures therefore provide an experimental platform for geometry-controlled optical-state accessibility. Full article

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

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23 pages, 22228 KB

Open AccessArticle

Multiscale Transfer of Cohesive-Zone Parameters for Opening-Dominated Interlaminar Fracture in Carbon-Fiber-Reinforced Aluminum Laminates

by Jiangwen Chen, Chaoqun Liang and Xin Luo

Polymers 2026, 18(18), 2287; https://doi.org/10.3390/polym18182287 (registering DOI) - 19 Sep 2026

Abstract

Specimen-scale fitting can reproduce interlaminar fracture in carbon-fiber-reinforced aluminum laminates (CARALL) but obscures the physical origin of cohesive-zone parameters. We present a multiscale framework integrating molecular dynamics (MD), a representative volume element (RVE), finite element (FE) modeling, and opening-dominated asymmetric double-cantilever-beam (DCB) tests. [...] Read more.

Specimen-scale fitting can reproduce interlaminar fracture in carbon-fiber-reinforced aluminum laminates (CARALL) but obscures the physical origin of cohesive-zone parameters. We present a multiscale framework integrating molecular dynamics (MD), a representative volume element (RVE), finite element (FE) modeling, and opening-dominated asymmetric double-cantilever-beam (DCB) tests. At modeled high rates, an ideal nonbonded Al/epoxy interface exhibited normal and tangential strengths of 470.09 and 352.93 MPa, respectively. Across 0.001–0.005 Å/fs, normal and tangential peak tractions increased by 5.93% and 5.82%, respectively, whereas traction-separation integrals varied nonmonotonically. These single-atomistic-realization descriptors were transferred to an RVE containing Al/matrix and fiber/matrix interfaces. In this morphology, fiber/matrix debonding preceded Al/matrix damage in all three realizations, and the RVE yielded mean effective normal and tangential strengths of 27.42 ± 0.33 and 39.04 ± 0.65 MPa, together with mean Mode I and Mode II fracture energies of 0.36 ± 0.02 and 0.81 ± 0.04 N/mm, respectively, where the means and standard deviations are taken over the three stochastic fiber realizations. The RVE-derived strengths and fracture energies were assigned directly to the DCB model without fitting the experimental response. The FE peak load was 44.48 N, 5.50% above the four-specimen mean of 42.16 ± 1.22 N, and the predicted damage location was qualitatively consistent with the observed Al/matrix interfacial damage. Because the interface model is idealized and the comparison rests on load–displacement data without synchronized crack-length measurements or independent fracture-resistance data, these results are reported as a configuration-specific assessment of the transfer procedure rather than as a quantitative validation; the transferred parameters are not intended to predict the chemically and structurally complex anodized interface. Full article

(This article belongs to the Special Issue Advances in Fatigue and Fracture of Fiber-Reinforced Polymers)

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