Polymers

18 pages, 1423 KB

Open AccessArticle

NaOH-Only Pretreated Wood Densification: A Simplified Sulfite-Free Route Across Wood Species

by Laura Andze, Vadims Nefjodovs, Juris Zoldners, Ulla Milbreta, Marite Skute, Linda Vecbiskena, Inese Filipova and Martins Andzs

Polymers 2026, 18(3), 312; https://doi.org/10.3390/polym18030312 (registering DOI) - 23 Jan 2026

Abstract

The development of high-performance wood-based materials has attracted increasing interest as a means of enhancing the mechanical properties of wood for structural applications. Mechanical densification combined with chemical pretreatment is an effective approach; however, many reported methods rely on complex multi-component chemical systems [...] Read more.

The development of high-performance wood-based materials has attracted increasing interest as a means of enhancing the mechanical properties of wood for structural applications. Mechanical densification combined with chemical pretreatment is an effective approach; however, many reported methods rely on complex multi-component chemical systems or severe chemical conditions designed to dissolve lignin or hemicelluloses. In this study, a simplified NaOH-only pretreatment followed by hot-press densification was investigated, targeting selective cell-wall plasticization rather than extensive polymer dissolution. Juniper (Juniperus communis), hawthorn (Crataegus monogyna), and birch (Betula pendula) were used as samples of softwood and hardwood species. Wood specimens were pretreated in 1 M NaOH at 145 °C for 10–30 min and subsequently densified by radial compression. Changes in chemical composition were evaluated by HPLC after acid hydrolysis and FTIR spectroscopy, while microstructural changes were examined using SEM. Physical and mechanical properties were assessed through density measurements and three-point bending tests. The results show that NaOH-only pretreatment induces hemicellulose deacetylation and modification of interpolymer linkages without substantial changes in the main wood polymer contents. Densification resulted in effective lumen collapse and a compact microstructure, leading to a significant increase in density and mechanical properties. Overall, the results demonstrate that efficient wood densification and mechanical enhancement can be achieved by promoting polymer mobility through selective cleavage of interpolymer bonds, using a simplified, single-alkali pretreatment that reduces chemical complexity and material loss while avoiding extensive lignin or hemicellulose dissolution. Full article

(This article belongs to the Special Issue Recent Progress on Lignocellulosic-Based Polymeric Materials)

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40 pages, 5950 KB

Open AccessReview

Innovative Physical and Chemical Strategies for the Modification and Development of Polymeric Microfiltration Membranes—A Review

by Mohammad Ebrahimi

Polymers 2026, 18(3), 311; https://doi.org/10.3390/polym18030311 (registering DOI) - 23 Jan 2026

Abstract

Polymeric microfiltration membranes are among the most utilized pressure-driven membranes due to their excellent permeation flux, moderate removal efficiency, low operating pressure, low cost, as well as their potential for reusability and cleanability. Therefore, these membranes are used in different crucial sectors, including [...] Read more.

Polymeric microfiltration membranes are among the most utilized pressure-driven membranes due to their excellent permeation flux, moderate removal efficiency, low operating pressure, low cost, as well as their potential for reusability and cleanability. Therefore, these membranes are used in different crucial sectors, including the water and wastewater, dairy, beverage, and pharmaceutical industries. However, well-known polymeric microfiltration membranes suffer from their poor hydrophilic properties, causing fouling phenomenon. A reduction in permeate flux, a shortened operational lifespan, and increased energy consumption are the primary negative consequences of membrane fouling. Over the years, a broad spectrum of studies has been performed to modify polymeric microfiltration membranes to improve their hydrophilic, transport, and antifouling characteristics. Despite extensive research, this issue remains a subject of ongoing discussion and scrutiny within the scientific community. This review article provides promising information about different physical and chemical modification methods—such as polymer blending, the incorporation of nanomaterials, surface coating, chemical crosslinking, in situ nanoparticle immobilization, and chemical surface functionalization—for polymeric microfiltration membranes. The physical and chemical modification methods are comparatively evaluated, highlighting their positive and negative aspects, supported by findings from recent investigations. Moreover, promising ideas and future-oriented techniques were proposed to obtain polymeric microfiltration membranes containing superior efficiency, extended service life, and mechanical strength. Full article

(This article belongs to the Special Issue Innovative Polymers and Technology for Membrane Fabrication)

21 pages, 10041 KB

Open AccessReview

Research Advances in Conjugated Polymer-Based Optical Sensor Arrays for Early Diagnosis of Clinical Diseases

by Qiuting Ye, Shijie Fan, Jieling Lao, Jiawei Xu, Xiyu Liu and Pan Wu

Polymers 2026, 18(3), 310; https://doi.org/10.3390/polym18030310 (registering DOI) - 23 Jan 2026

Abstract

Early and accurate diagnosis is critical for disease surveillance, therapeutic guidance, and relapse monitoring. Sensor arrays have emerged as a multi-analyte detection tool via non-specific interactions to generate unique fingerprint patterns with high levels of selectivity and discrimination. Conjugated polymers (CPs), with their [...] Read more.

Early and accurate diagnosis is critical for disease surveillance, therapeutic guidance, and relapse monitoring. Sensor arrays have emerged as a multi-analyte detection tool via non-specific interactions to generate unique fingerprint patterns with high levels of selectivity and discrimination. Conjugated polymers (CPs), with their tunable π-conjugated backbones, exceptional light-harvesting capability, and efficient “molecular wire effect,” provide an ideal and versatile material platform for such arrays, enabling significant optical signal amplification and high sensitivity. This review systematically outlines the rational design and functionalization strategies of CPs for constructing high-performance sensor arrays. It delves into the structure–property relationships that govern their sensing performance, covering main-chain engineering, side-chain functionalization, and microenvironmental regulation. Representative applications are discussed, including non-small cell lung cancer, breast cancer, bacterial and viral infections, Alzheimer’s disease, and diabetic nephropathy, highlighting the remarkable diagnostic capabilities achieved through tailored CP materials. Finally, future perspectives are focused on novel material designs and device integration to advance this vibrant field. Full article

(This article belongs to the Section Polymer Applications)

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22 pages, 3208 KB

Open AccessArticle

Validated Cohesive Zone Models for Epoxy-Based Adhesive Joints Between Steel and CFRP Composites for Multimaterial Structural Design in Transportation Applications

by Stanislav Špirk and Tomáš Kalina

Polymers 2026, 18(3), 309; https://doi.org/10.3390/polym18030309 (registering DOI) - 23 Jan 2026

Abstract

This study presents the development, calibration, and validation of cohesive zone models (CZMs) for epoxy-based adhesive joints connecting stainless steel and CFRP composites. The objective of this study is to develop and rigorously validate cohesive zone models for epoxy-based adhesive joints between stainless [...] Read more.

This study presents the development, calibration, and validation of cohesive zone models (CZMs) for epoxy-based adhesive joints connecting stainless steel and CFRP composites. The objective of this study is to develop and rigorously validate cohesive zone models for epoxy-based adhesive joints between stainless steel and CFRP composites, ensuring their reliability for numerical simulations of structural failure under quasi-static and large-deformation conditions. The work focuses on accurately describing the quasi-static behaviour and failure mechanisms of hybrid adhesive interfaces, which are crucial for multimaterial structures in modern transportation systems. Experimental tests in Mode I (DCB) and Mode II (ENF) configurations were performed to determine the cohesive parameters of the structural adhesive SikaPower 1277. The obtained data were further analysed through analytical formulations and validated numerically using PAM-CRASH. Excellent agreement was achieved between experiments, analytical predictions, and simulations, confirming the reliability of the proposed material definitions under large deformations. The validated models were subsequently implemented in a large-scale numerical simulation of a bus rollover according to UN/ECE Regulation No. 66, demonstrating their applicability to real structural components. The results show that the developed cohesive zone models enable accurate prediction of failure initiation and propagation in adhesive joints between dissimilar materials. These findings provide a robust foundation for the design of lightweight, crashworthy structures in transportation and open new perspectives for integrating epoxy-based adhesives into additively manufactured hybrid metal–composite systems. Full article

(This article belongs to the Section Polymer Applications)

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19 pages, 2597 KB

Open AccessArticle

Multiscale Synergistic Investigation on the Mechanical and Tribological Performances of Graphene-Reinforced PEEK/PTFE Composites

by Yan Wang, Kaiqi Dong, Henan Tang, Bin Yang and Shijie Wang

Polymers 2026, 18(3), 308; https://doi.org/10.3390/polym18030308 (registering DOI) - 23 Jan 2026

Abstract

Polytetrafluoroethylene (PTFE) is a self-lubricating material but has poor wear resistance. The wear resistance of the composites was enhanced by the incorporation of polyetheretherketone (PEEK), whereas the friction-reducing performance was compromised, thus resulting in an inherent trade-off between wear resistance and lubricity. Graphene [...] Read more.

Polytetrafluoroethylene (PTFE) is a self-lubricating material but has poor wear resistance. The wear resistance of the composites was enhanced by the incorporation of polyetheretherketone (PEEK), whereas the friction-reducing performance was compromised, thus resulting in an inherent trade-off between wear resistance and lubricity. Graphene nanosheets (GNSs) with high strength and lubricity were introduced as a reinforcement for PEEK/PTFE composites. Composite specimens with varying GNS contents were fabricated and characterized for their mechanical and tribological properties and wear morphologies. Combined with molecular dynamics (MD) simulations, the micro-mechanisms were further elucidated. The optimal GNS content was determined to be 2 wt%, which improved the tensile strength by 10.58% and reduced the wear rate by 17.88% compared to PEEK/PTFE. It achieved the synchronous enhancement of mechanical strength and wear resistance while maintaining desirable friction-reducing performance. MD simulation results demonstrated that the strong interfacial interactions between GNSx and the polymer enabled GNSs to adsorb polymer chains and form a dense rigid network with reduced free volume (FV). The mechanical properties were enhanced by efficient load transfer and the suppression of interfacial delamination enabled by this unique structure; meanwhile, wear resistance was improved due to the mitigation of friction-induced molecular chain scission. Full article

(This article belongs to the Special Issue Advances in the Structure and Mechanical Properties of Polymer Composites)

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23 pages, 3790 KB

Open AccessArticle

AI-Powered Thermal Fingerprinting: Predicting PLA Tensile Strength Through Schlieren Imaging

by Mason Corey, Kyle Weber and Babak Eslami

Polymers 2026, 18(3), 307; https://doi.org/10.3390/polym18030307 (registering DOI) - 23 Jan 2026

Abstract

Fused deposition modeling (FDM) suffers from unpredictable mechanical properties in nominally identical prints. Current quality assurance relies on destructive testing or expensive post-process inspection, while existing machine learning approaches focus primarily on printing parameters rather than real-time thermal environments. The objective of this [...] Read more.

Fused deposition modeling (FDM) suffers from unpredictable mechanical properties in nominally identical prints. Current quality assurance relies on destructive testing or expensive post-process inspection, while existing machine learning approaches focus primarily on printing parameters rather than real-time thermal environments. The objective of this proof-of-concept study is to develop a low-cost, non-destructive framework for predicting tensile strength during FDM printing by directly measuring convective thermal gradients surrounding the print. To accomplish this, we introduce thermal fingerprinting: a novel non-destructive technique that combines Background-Oriented Schlieren (BOS) imaging with machine learning to predict tensile strength during printing. We captured thermal gradient fields surrounding PLA specimens (n = 30) under six controlled cooling conditions using consumer-grade equipment (Nikon D750 camera, household hairdryers) to demonstrate low-cost implementation feasibility. BOS imaging was performed at nine critical layers during printing, generating thermal gradient data that was processed into features for analysis. Our initial dual-model ensemble system successfully classified cooling conditions (100%) and showed promising correlations with tensile strength (initial 80/20 train–test validation: R² = 0.808, MAE = 0.279 MPa). However, more rigorous cross-validation revealed the need for larger datasets to achieve robust generalization (five-fold cross-validation R² = 0.301, MAE = 0.509 MPa), highlighting typical challenges in small-sample machine learning applications. This work represents the first successful application of Schlieren imaging to polymer additive manufacturing and establishes a methodological framework for real-time quality prediction. The demonstrated framework is directly applicable to real-time, non-contact quality assurance in FDM systems, enabling on-the-fly identification of mechanically unreliable prints in laboratory, industrial, and distributed manufacturing environments without interrupting production. Full article

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

42 pages, 6173 KB

Open AccessReview

Integrating Artificial Intelligence into Circular Strategies for Plastic Recycling and Upcycling

by Allison Vianey Valle-Bravo, Carlos López González, Rosalía América González-Soto, Luz Arcelia García Serrano, Juan Antonio Carmona García and Emmanuel Flores-Huicochea

Polymers 2026, 18(2), 306; https://doi.org/10.3390/polym18020306 (registering DOI) - 22 Jan 2026

Abstract

The increasing urgency to mitigate plastic pollution has accelerated the shift from linear manufacturing toward circular systems. This review synthesizes current advances in mechanical, chemical, biological, and upcycling pathways, emphasizing how artificial intelligence (AI) is reshaping decision-making, performance prediction, and system-level optimization. Intelligent [...] Read more.

The increasing urgency to mitigate plastic pollution has accelerated the shift from linear manufacturing toward circular systems. This review synthesizes current advances in mechanical, chemical, biological, and upcycling pathways, emphasizing how artificial intelligence (AI) is reshaping decision-making, performance prediction, and system-level optimization. Intelligent sensing technologies—such as FTIR, Raman spectroscopy, hyperspectral imaging, and LIBS—combined with Machine Learning (ML) classifiers have improved material identification, reduced reject rates, and enhanced sorting precision. AI-assisted kinetic modeling, catalyst performance prediction, and enzyme design tools have improved process intensification for pyrolysis, solvolysis, depolymerization, and biocatalysis. Life Cycle Assessment (LCA)-integrated datasets reveal that environmental benefits depend strongly on functional-unit selection, energy decarbonization, and substitution factors rather than mass-based comparisons alone. Case studies across Europe, Latin America, and Asia show that digital traceability, Extended Producer Responsibility (EPR), and full-system costing are pivotal to robust circular outcomes. Upcycling strategies increasingly generate high-value materials and composites, supported by digital twins and surrogate models. Collectively, evidence indicates that AI moves from supportive instrumentation to a structural enabler of transparency, performance assurance, and predictive environmental planning. The convergence of AI-based design, standardized LCA frameworks, and inclusive governance emerges as a necessary foundation for scaling circular plastic systems sustainably. Full article

(This article belongs to the Special Issue New Progress in the Recycling of Plastics)

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26 pages, 1937 KB

Open AccessArticle

Design and Optimization of Pullulan-Isononanoate Films with Bioactive-Loaded Liposomes for Potential Biomedical Use

by Amjed A. Karkad, Aleksandar Marinković, Aleksandra Jovanović, Katarina Simić, Stefan Ivanović, Milena Milošević and Tamara Erceg

Polymers 2026, 18(2), 305; https://doi.org/10.3390/polym18020305 (registering DOI) - 22 Jan 2026

Abstract

This study reports the synthesis and detailed characterization of pullulan-isononanoate (Pull-Iso), as well as the preparation and characterization of Pull-Iso films incorporating liposomes loaded with silibinin (SB) and smoke tree (Cotinus coggygria) extract (STExt), to explore the physicochemical and functional properties [...] Read more.

This study reports the synthesis and detailed characterization of pullulan-isononanoate (Pull-Iso), as well as the preparation and characterization of Pull-Iso films incorporating liposomes loaded with silibinin (SB) and smoke tree (Cotinus coggygria) extract (STExt), to explore the physicochemical and functional properties of pullulan-based biomaterials for potential biomedical applications. Pullulan was successfully esterified with isononanoic acid chloride, as confirmed by ¹H and ¹³C NMR (Nuclear Magnetic Resonance) and Fourier Transform Infrared (FTIR) spectroscopy. Modification significantly reduced the glass transition temperature (Tg), indicating enhanced chain mobility due to the introduction of bulky side chains. Prepared liposomes, embedding SB and extracted smoke tree compounds, exhibited particle sizes ~2000 nm with moderate polydispersity (~0.340) and zeta potential values around –20 mV, demonstrating lower colloidal stability over 60 days, thereby justifying their encapsulation within films. Optical microscopy revealed uniform liposome dispersion in Pull-Iso film with 0.5 g of liposomes, while higher liposome loading (0.75 g of liposomes) induced aggregation and microstructural irregularities. Mechanical analysis showed a reduction in tensile strength and strain at higher liposome content. The incorporation of liposomes encapsulating STExt and SB significantly enhanced the antioxidant activity of Pull-Iso-based films in a concentration-dependent manner, as demonstrated by DPPH and ABTS radical scavenging assays. These preliminary findings suggest that pullulan esterification and controlled liposome incorporation may enable the development of flexible, bioactive-loaded films, which could represent a promising platform for advanced wound dressing applications, warranting further investigation. Full article

(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials, 3rd Edition)

22 pages, 1282 KB

Open AccessArticle

Synthesis and Degradation Behavior of Poly(Glycerol Sebacate)-Isophorone Diisocyanate Scaffolds Reinforced with Hydroxyapatite for Biomedical Applications

by Aleksandra Korbut, Agnieszka Sobczak-Kupiec, Monika Biernat and Sonia Zielińska

Polymers 2026, 18(2), 304; https://doi.org/10.3390/polym18020304 (registering DOI) - 22 Jan 2026

Abstract

Poly(glycerol sebacate) (PGS) is a biodegradable elastomer with high potential for tissue engineering. However, its limited structural stability and degradation control restrict broader biomedical applications. This study presents an integrated fabrication strategy for highly porous PGS-IPDI scaffolds reinforced with two types of hydroxyapatite [...] Read more.

Poly(glycerol sebacate) (PGS) is a biodegradable elastomer with high potential for tissue engineering. However, its limited structural stability and degradation control restrict broader biomedical applications. This study presents an integrated fabrication strategy for highly porous PGS-IPDI scaffolds reinforced with two types of hydroxyapatite of distinct origin (HAP_B and HAP_ICMB). By combining low-temperature urethane crosslinking with thermally induced phase separation and salt leaching, we obtained scaffolds with interconnected micro–macroporous architectures and exceptionally high porosity (up to 98%). The comparative incorporation of phase-pure nanometric HAP_B and biphasic HAP_ICMB enabled the identification of composition-dependent differences in water uptake, structural stability, and mineralization tendencies. Furthermore, degradation behavior was systematically evaluated in four physiologically relevant media (PBS, SBF, artificial saliva, Ringer’s solution), revealing distinct degradation pathways associated with each environment. The results provide new insight into how hydroxyapatite type and incubation medium collectively govern the long-term performance of chemically crosslinked PGS-based scaffolds. Full article

(This article belongs to the Special Issue From Polymers Design to Advanced Structures for Biomedical Applications)

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23 pages, 4455 KB

Open AccessArticle

pH-Responsive mPEG-PLGA/Dexamethasone Coatings for Corrosion Control and Osteo-Immune Modulation of Biodegradable Magnesium

by Yu-Kyoung Kim, Seo-Young Kim, Yong-Seok Jang and Min-Ho Lee

Polymers 2026, 18(2), 303; https://doi.org/10.3390/polym18020303 (registering DOI) - 22 Jan 2026

Abstract

This study aimed to control rapid localized corrosion and inflammation of biodegradable magnesium implants by developing a pH-responsive mPEG-PLGA coating loaded with dexamethasone (Dex). The mPEG-PLGA layer was designed to selectively degrade in alkaline conditions, thereby moderating pH elevation at the implant surface [...] Read more.

This study aimed to control rapid localized corrosion and inflammation of biodegradable magnesium implants by developing a pH-responsive mPEG-PLGA coating loaded with dexamethasone (Dex). The mPEG-PLGA layer was designed to selectively degrade in alkaline conditions, thereby moderating pH elevation at the implant surface while enabling controlled Dex release. By varying the molecular weight of mPEG and PLGA, the degradation rate and microsphere size were tunable, allowing adjustment of the drug release profile. Among the tested coating solution concentrations (1.5–7.5 mg/mL), the formulation with 3 mg/mL Dex yielded a final cumulative release concentration of 0.02 mg/mL over a two-week period, which suppressed inflammatory responses in RAW 264.7 macrophages with minimal cytotoxicity, while enhancing BMP-2 and RUNX2 expression in mesenchymal stem cells. In a rat femur defect model, Mg implants coated with mPEG-PLGA containing 3 mg/mL Dex significantly increased bone volume and bone mineral density and reduced early TNF-α expression, accompanied by continuous new bone formation and strong BSP-positive osseointegration. These findings suggest that the proposed pH-responsive mPEG-PLGA/Dex coating provides a promising strategy to simultaneously regulate corrosion, attenuate inflammation, and promote bone regeneration around magnesium implants. Full article

(This article belongs to the Special Issue Hydrogels, Biopolymers, and Applications as Antimicrobial Agents)

24 pages, 5920 KB

Open AccessArticle

Mechanical, Fatigue, and Thermal Characterization of ASA, Nylon 12, PC, and PC-ABS Manufactured by Fused Filament Fabrication (FFF)

by Ângela Rodrigues, Ricardo Branco, Margarida Franco, Rui Silva, Cândida Malça and Rui F. Martins

Polymers 2026, 18(2), 302; https://doi.org/10.3390/polym18020302 (registering DOI) - 22 Jan 2026

Abstract

Additive manufacturing has been widely adopted in industry as an alternative to traditional manufacturing processes for complex component production. In fact, a diverse range of materials, particularly polymers, can be processed using 3D printing for biomechanical applications (e.g., prosthetics). However, in-depth evaluation of [...] Read more.

Additive manufacturing has been widely adopted in industry as an alternative to traditional manufacturing processes for complex component production. In fact, a diverse range of materials, particularly polymers, can be processed using 3D printing for biomechanical applications (e.g., prosthetics). However, in-depth evaluation of these materials is necessary to determine their suitability for demanding applications, such as those involving cyclic loading. Following previous work that studied Polylactic Acid (PLA) and Polyethylene Terephthalate Glycol-modified (PETG) under experimental fatigue testing, this study examines the fatigue behaviour of other current 3D-printed polymeric materials, namely Acrylonitrile Styrene Acrylate (ASA), Polycarbonate (PC), Polyamide 12 (Nylon 12), and Polycarbonate–Acrylonitrile Butadiene Styrene (blend) (PC-ABS), for which fatigue data remain limited or even non-existent. The findings revealed performance differences on Tensile Strength (σ_R), Young’s Modulus and Ultimate Strain among tensile specimens made from these materials and characterised S-N curves for both high-cycle (HCF) and low-cycle (LCF) fatigue regimes at room temperature, with a tensile load ratio (R = 0.05). These results establish relationships among fatigue limit and quasi-static mechanical properties, namely 25% × σ_r for ASA (8 MPa), 7% × σ_r for PC (3.6 MPa), 17% × σ_r for Nylon 12 (7.4 MPa), and 15% × σ_r for PC-ABS (4.7 MPa), as well as between mechanical properties and preliminary potential biomechanical applications. Main conclusions were further supported by micro-computed tomography (micro-CT), which revealed levels of porosity in between 4% and 11%, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Full article

(This article belongs to the Special Issue Research Progress on Mechanical Behavior of Polymers, 2nd Edition)

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56 pages, 5116 KB

Open AccessReview

Biobased Polymers in Printed Electronics: From Renewable Resources to Functional Devices

by Dimitra Karavasili, Kyriaki Lazaridou, Maria Angeliki Ntrivala, Andreas Chrysovalantis Pitsavas, Zafeiria Baziakou, Maria Papadimitriou, Nikolaos D. Bikiaris, Evangelia Balla and Ζoi Terzopoulou

Polymers 2026, 18(2), 301; https://doi.org/10.3390/polym18020301 (registering DOI) - 22 Jan 2026

Abstract

Printed electronics (PE) have emerged as a rapidly growing technology owing to their potential for low-cost fabrication, flexibility, and scalable device manufacturing. The dependence on fossil-based components raises environmental concerns, leading the scientific community toward sustainable solutions, aiming to reduce the accumulation of [...] Read more.

Printed electronics (PE) have emerged as a rapidly growing technology owing to their potential for low-cost fabrication, flexibility, and scalable device manufacturing. The dependence on fossil-based components raises environmental concerns, leading the scientific community toward sustainable solutions, aiming to reduce the accumulation of electronic waste (e-waste) in the environment and the emission of toxic gases, as well as to offer a circular solution in the sector. This review presents an in-depth overview of biobased polymeric materials in printed and organic (bio-)electronics. Firstly, the principal printing techniques are presented in detail. The review proceeds by outlining the various biobased synthetic and natural polymers, along with their blends, that are employed in the fabrication of biobased substrates for printed devices. Finally, the review emphasizes the existing challenges and constraints in the field of PE, along with the promising opportunities for its future advancement. Full article

(This article belongs to the Collection Biodegradable Polymers and Polymeric Composite)

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16 pages, 5786 KB

Open AccessArticle

Advancing Circular Composite Strategies by Vitrimer-Enabled Reuse of Unidirectional Laminates

by Jannick Fuchs, Nico Schuhmann, Jonathan Alms and Christian Hopmann

Polymers 2026, 18(2), 300; https://doi.org/10.3390/polym18020300 (registering DOI) - 22 Jan 2026

Abstract

To efficiently reuse endless fibre-reinforced composites after their life cycle, the recovery of endless fibres including matrix material with subsequent reprocessing in their original state is desirable. Thanks to their covalent adaptive networks, vitrimers offer ideal properties for enabling new repair and circular [...] Read more.

To efficiently reuse endless fibre-reinforced composites after their life cycle, the recovery of endless fibres including matrix material with subsequent reprocessing in their original state is desirable. Thanks to their covalent adaptive networks, vitrimers offer ideal properties for enabling new repair and circular strategies for composites. In order to evaluate the detachability—meaning the separation of single laminate layers—and recycling potential for continuous fibre reinforcement, process routes and quality parameters must be established. In this study, the double cantilever beam test is used to test the adhesion based on the detachment of continuous fibre layers, and the interlaminare fracture toughness of mode I (G_IC) is measured as a parameter for the required energy for detachment. It was shown that G_IC increases above the vitrimer transition temperature and is higher than for reference specimens with an epoxy matrix. Surface roughness is measured to determine the mechanical and thermal degradation of the chemical network structure and additionally shows fibre cracking and defects in fibre–matrix interfaces. This allows the recycling process to be evaluated up to the production of a second generation, with the aim of identifying the recycling potential of the vitrimer matrix and implementing it for industrial processes. An efficient recycling strategy of the continuous fibre-reinforced vitrimers was thus demonstrated by hot pressing at 190 °C for 45 min, giving vitrimer samples a second life. Full article

(This article belongs to the Section Innovation of Polymer Science and Technology)

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38 pages, 7740 KB

Open AccessReview

Waterborne Poly(urethane-urea)s for Lithium-Ion/Lithium-Metal Batteries

by Bushra Rashid, Anjum Hanief Kohli and In Woo Cheong

Polymers 2026, 18(2), 299; https://doi.org/10.3390/polym18020299 (registering DOI) - 22 Jan 2026

Abstract

Waterborne polyurethane (WPU) and waterborne poly(urethane-urea) (WPUU) dispersions allow safer and more sustainable manufacturing of rechargeable batteries via water-based processing, while offering tunable adhesion and segmented-domain mechanics. Beyond conventional roles as binders and coatings, WPU/WPUU chemistries also support separator/interlayer and polymer-electrolyte designs for [...] Read more.

Waterborne polyurethane (WPU) and waterborne poly(urethane-urea) (WPUU) dispersions allow safer and more sustainable manufacturing of rechargeable batteries via water-based processing, while offering tunable adhesion and segmented-domain mechanics. Beyond conventional roles as binders and coatings, WPU/WPUU chemistries also support separator/interlayer and polymer-electrolyte designs for lithium-ion and lithium metal systems, where interfacial integrity, stress accommodation, and ion transport must be balanced. Here, we review WPU/WPUU fundamentals (building blocks, dispersion stabilization, morphology, and film formation) and review prior studies through a battery-centric structure–processing–property lens. We point out key performance-limiting trade-offs—adhesion versus electrolyte uptake and ionic conductivity versus storage modulus—and relate them to practical formulation variables, including soft-/hard-segment selection, ionic center/counterion design, molecular weight/topology control, and crosslinking strategies. Applications are reviewed for (i) electrode binders (graphite/Si; cathodes such as LFP and NMC), (ii) separator coatings and functional interlayers, and (iii) gel/solid polymer electrolytes and hybrid composites, with a focus on practical design guidelines for navigating these trade-offs. Future advancements in WPU/WPUU chemistries will depend on developing stable, low-impedance interlayers, enhancing electrochemical behavior, and establishing application-specific design guidelines to optimize performance in lithium metal batteries (LMB). Full article

(This article belongs to the Section Polymer Applications)

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27 pages, 6495 KB

Open AccessArticle

Linear Polyethyleneimine-Coated Gold Nanoparticles as a Platform for Central Nervous System Targeting

by Agustín J. Byrne, Antonia Infantes-Molina, Enrique Rodríguez-Castellón, Romina J. Glisoni, María J. Pérez, Patrizia Andreozzi, Barbara Richichi, Marco Marradi, Paula G. Franco and Juan M. Lázaro-Martínez

Polymers 2026, 18(2), 298; https://doi.org/10.3390/polym18020298 (registering DOI) - 22 Jan 2026

Abstract

The unique physicochemical properties of gold nanoparticles (GNPs) have made them versatile tools for biomedical applications, such as imaging, therapy, and drug delivery. The surface modification of GNPs with polymers or biomolecules can enhance their colloidal stability and facilitate internalization into cells. However, [...] Read more.

The unique physicochemical properties of gold nanoparticles (GNPs) have made them versatile tools for biomedical applications, such as imaging, therapy, and drug delivery. The surface modification of GNPs with polymers or biomolecules can enhance their colloidal stability and facilitate internalization into cells. However, the efficient and biocompatible delivery to the central nervous system remains a major challenge, as many existing nanocarriers show poor capacity to cross the blood-brain barrier. We developed a method to coat GNPs with linear polyethyleneimine (GNP@PEI) through a chemical reduction bottom-up approach, in which linear PEI hydrochloride acts simultaneously as a reducing and stabilizing agent of colloidal dispersion. This strategy yielded monodisperse spherical GNP@PEI nanoparticles with an average diameter of 50 nm. The physicochemical profile, biocompatibility, and capacity for neural uptake of this potentially brain-targeted nanoplatform were then evaluated. GNP@PEI nanoparticles exhibited high biocompatibility in several primary neural cultures and cell lines, with cellular uptake showing clear cell-type-dependent differences. In vivo studies carried out in a murine model demonstrated that after the intranasal or intraperitoneal administrations of GNP@PEI nanoparticles, detectable levels of gold were found in several organs, including the brain. Collectively, these findings highlight the potential of GNP@PEI as a promising nanoplatform for brain-targeted delivery and for advancing the development of therapeutic strategies for neurological disorders. Full article

(This article belongs to the Topic Polymer and Biopolymer Nanocomposites for Emerging Medical, Industrial, and Environmental Applications)

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12 pages, 2588 KB

Open AccessArticle

Low-Odor High-Density Fiberboard Enabled by Supramolecular Interactions in Wood Fibers

by Xia Yu, Zongying Fu, Bo Liu, Xiaoxuan Guo, Yun Lu and Lihong Yao

Polymers 2026, 18(2), 297; https://doi.org/10.3390/polym18020297 (registering DOI) - 22 Jan 2026

Abstract

The development of sustainable wood-based composites has driven increasing interest in formaldehyde-free, low-odor, and recyclable bonding systems. However, achieving high mechanical performance and dimensional stability in high-density fiberboards (HDFs) without synthetic adhesives remains a challenge. Here, we report a two-step strategy combining oxidative [...] Read more.

The development of sustainable wood-based composites has driven increasing interest in formaldehyde-free, low-odor, and recyclable bonding systems. However, achieving high mechanical performance and dimensional stability in high-density fiberboards (HDFs) without synthetic adhesives remains a challenge. Here, we report a two-step strategy combining oxidative pretreatment of wood fibers with supramolecular assembly of tannic acid (TA) and sodium ions (Na⁺) to fabricate low-odor, recyclable HDF. Oxidation generated abundant carboxyl groups on the fiber surface, enabling strong coordination and hydrogen-bonding interactions between TA and Na⁺, which constructed robust inter-fiber supramolecular networks without formaldehyde-based adhesives. The resulting HDF exhibited excellent mechanical properties, with an internal bond strength of 3.1 MPa, a modulus of rupture of 49 MPa, and 24 h water thickness swelling of only 12%. Odor and VOC analysis revealed only trace benzene, demonstrating markedly low odor. Furthermore, the reversible nature of Na⁺-TA interactions allowed efficient fiber separation and recyclability under mild aqueous conditions. This oxidation-assisted supramolecular approach provides a sustainable route for producing high-performance, low-odor, and recyclable fiberboards, offering a viable alternative to conventional polymer-bonded wood composites. Full article

(This article belongs to the Section Polymer Chemistry)

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16 pages, 1662 KB

Open AccessArticle

Shear Bond Strength of Additively and Subtractively Manufactured CAD/CAM Restorative Materials After Different Surface Treatments and Adhesive Strategies: An In Vitro Study

by Sevim Atilan Yavuz, Ayse Tugba Erturk-Avunduk, Omer Sagsoz, Ebru Delikan and Ozcan Karatas

Polymers 2026, 18(2), 296; https://doi.org/10.3390/polym18020296 (registering DOI) - 22 Jan 2026

Abstract

This study aims to evaluate the effects of different surface treatments and adhesive systems on the shear bond strength (SBS) of additively manufactured (AM) and subtractively manufactured (SM) restorative materials. A total 675 rectangular specimens of three AM (Saremco Crowntec/SC, VarseoSmile CrownPlus/VC, and [...] Read more.

This study aims to evaluate the effects of different surface treatments and adhesive systems on the shear bond strength (SBS) of additively manufactured (AM) and subtractively manufactured (SM) restorative materials. A total 675 rectangular specimens of three AM (Saremco Crowntec/SC, VarseoSmile CrownPlus/VC, and VarseoSmile TriniQ/VT) and two SM (Vita Enamic/VE and Cerasmart/CS) restorative materials were fabricated. Each material was randomly divided into three groups regarding surface treatments: control/C, sandblasting/S, and etching/E. Following surface treatments, each AM and SM restorative material was then divided into three subgroups (15 specimens/subgroup) on the basis of adhesive systems (etch-and-rinse, self-etch, and universal). All specimens were thermocycled at 10,000 cycles, 5–55 °C, 30 s dwell time, and tested under SBS until failure, and failure types were examined under a stereomicroscope. Representative specimens were examined by SEM to evaluate fracture morphology. Statistical analysis was set at p < 0.05. There were significant differences in bond strength according to the material, surface treatment, adhesives, and their interactions (p < 0.05). The highest SBS value was obtained with SC × sandblasting × etch-and-rinse (16.45 ± 0.93 MPa), while the lowest value was found in the CS × control × universal interaction (4.68 ± 1.1 MPa). Outcomes varied according to the materials, surface treatment, and adhesive strategy. Clinically, these findings indicate that SM materials may require various surface treatment to achieve reliable adhesion, whereas AM materials provide more similar bond strength performance with no surface treatment. Full article

(This article belongs to the Special Issue Additive Manufacturing of Polymer Based Materials)

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15 pages, 3071 KB

Open AccessArticle

Green-Synthesized TIO₂ Nanoparticles Improve Mechanical Performance of Glass Ionomer Cements

by Nevra Karamüftüoğlu, Süha Kuşçu, İpek Kuşçu and Nesrin Korkmaz

Polymers 2026, 18(2), 295; https://doi.org/10.3390/polym18020295 (registering DOI) - 22 Jan 2026

Abstract

Glass ionomer cements (GICs) are widely used in restorative and luting dentistry due to their fluoride release and chemical adhesion to dental tissues; however, their limited mechanical strength necessitates reinforcement strategies. The objective of this study was to investigate the effects of hemp-derived, [...] Read more.

Glass ionomer cements (GICs) are widely used in restorative and luting dentistry due to their fluoride release and chemical adhesion to dental tissues; however, their limited mechanical strength necessitates reinforcement strategies. The objective of this study was to investigate the effects of hemp-derived, green-synthesized titanium dioxide (TiO₂) nanoparticles on the surface and mechanical properties of two commercially available GICs with different clinical indications. TiO₂ nanoparticles were synthesized using Cannabis sativa leaf extract via a biogenic reduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), confirming anatase-phase crystallinity, spherical morphology, and nanoscale particle size (28–49 nm). The nanoparticles were incorporated into Ketac™ Molar Easymix (restorative) and Ketac™ Cem Radiopaque (luting) GICs at 1%, 3%, and 5% (w/w), with nanoparticle-free formulations serving as controls (n = 10). Surface roughness, Vickers microhardness, and flexural strength were evaluated. Surface roughness increased in a concentration-dependent manner in both materials, with the highest values observed at 5% TiO₂ incorporation. In Ketac™ Molar Easymix, 1% and 3% TiO₂ significantly enhanced flexural strength and microhardness, whereas 5% resulted in reduced performance, consistent with SEM-observed nanoparticle agglomeration. In contrast, Ketac™ Cem Radiopaque exhibited no significant changes in flexural strength, although maximum microhardness values were recorded at 1% TiO₂ concentration. These findings demonstrate that low concentrations of hemp-derived TiO₂ nanoparticles can effectively reinforce restorative GICs and highlight the potential of green nanotechnology as a sustainable approach for improving dental biomaterials. Full article

(This article belongs to the Section Polymer Applications)

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22 pages, 5760 KB

Open AccessArticle

Polylactide/Polycaprolactone Nanofiber Scaffold Enhances Primary Cortical Neuron Growth

by Valeriia S. Shtol, Anastasiia D. Tsareva, Kirill A. Arsentiev, Sophia P. Konovalova, Suanda A. Tlimahova, Dmitry V. Klinov, Dimitri A. Ivanov and Pavel E. Musienko

Polymers 2026, 18(2), 294; https://doi.org/10.3390/polym18020294 (registering DOI) - 21 Jan 2026

Abstract

Spinal cord injury (SCI) remains a major clinical challenge due to the limited regenerative capacity of the central nervous system (CNS). Effective scaffolds for repair must combine mechanical compatibility with host tissue, controlled degradation matching the time course of regeneration, and microarchitectural features [...] Read more.

Spinal cord injury (SCI) remains a major clinical challenge due to the limited regenerative capacity of the central nervous system (CNS). Effective scaffolds for repair must combine mechanical compatibility with host tissue, controlled degradation matching the time course of regeneration, and microarchitectural features that promote neuronal survival. Electrospun nanofibrous scaffolds mimic the structural and mechanical features of the extracellular matrix, providing critical cues for neuronal adhesion and glial modulation in neural regeneration. Here, we fabricated biodegradable poly(lactic acid)/poly(ε-caprolactone) (PLA/PCL) scaffolds using a dichloromethane/tetrahydrofuran (DCM/THF) solvent system to induce surface porosity via solvent-driven phase separation. The DCM/THF solvent system formulation produced nanofibers with porous surfaces and increased area for cell interaction. PLA/PCL scaffolds showed a Young’s modulus of ~26 MPa and sustained degradation, particularly under oxidative conditions simulating the post-injury microenvironment. In vitro, these scaffolds enhanced neuronal density up to fivefold and maintained ~80% viability over 10 days in primary neuron–glia cultures. Morphometric analysis revealed that DCM/THF-based scaffolds supported astrocytes with preserved process complexity and reduced circularity, indicative of a less reactive morphology. In contrast, scaffolds fabricated with 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) displayed reduced bioactivity and promoted morphological features associated with astrocyte reactivity, including cell rounding and process retraction. These findings demonstrate that solvent-driven control of scaffold microarchitecture is a powerful strategy to enhance neuronal integration and modulate glial morphology, positioning DCM/THF-processed PLA/PCL scaffolds as a promising platform for CNS tissue engineering. Full article

(This article belongs to the Special Issue Biodegradable Polymers for Sustainable Solutions: Innovations and Applications)

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