Search Results (2,547)

Hyaluronic acid (HA) hydrogels have attracted increasing interest for biomedical applications due to their tunable properties and biocompatibility. Methods: In this study, hyaluronic acid HA-based hydrogels were developed using two distinct crosslinking strategies: physical crosslinking through poly(vinyl alcohol) (PVA) incorporation and covalent crosslinking via DCC/NHS-mediated reactions. Piroxicam (Px) was included as a model drug to evaluate the drug delivery potential of the resulting systems. The hydrogels were characterized in terms of morphology, swelling behaviour, adhesion, enzymatic degradation, drug release, and in vitro cytocompatibility. Results: The results indicate that formulation parameters significantly influence the overall performance of the systems. PVA-containing hydrogels exhibited higher swelling capacity and improved adhesive properties, while covalently crosslinked networks showed reduced swelling and enhanced structural stability and resistance to enzymatic degradation. Drug release profiles were dependent on network structure, with more compact systems displaying slower release behaviour. In vitro assays suggested that the developed hydrogels are cytocompatible and that drug incorporation influences both release kinetics and cellular response. However, it should be noted that the biological evaluation was performed under simplified in vitro conditions, which primarily reflect specific aspects such as cell viability and migration. Conclusions: This study provides a comparative analysis of physical and covalent crosslinking strategies within a HA platform and highlights how formulation variables influence key physicochemical and biological properties. These findings contribute to the rational design of HA-based hydrogels, although further studies are required to establish their performance in more complex biological environments. Full article

Branched poly(vinyl alcohol) (PVA) was synthesized via chemical modification of linear PVA with epichlorohydrin in an alkaline aqueous medium under conditions preventing crosslinking. Branching was confirmed by IR and Heteronuclear Single Quantum Coherence (HSQC) spectroscopy, as well as by viscometric analysis. An iterative procedure is proposed for refining the branching factor (g) and the viscosity-average molecular weight of the branched macromolecules. Coil diameters determined by viscometry and dynamic light scattering showed satisfactory agreement. While an increase in the viscosity-average molecular weight of branched PVA enhances its surface activity in the low-adsorption region, the branched geometry itself hinders subsequent adsorption due to steric shielding of the interface. This correlates with wetting behavior on Teflon: lightly branched PVA requires a higher concentration to induce wetting inversion than its linear counterpart but further increase in molecular weight shifts the inversion point to lower concentrations due to a higher density of hydroxyl groups. Concurrently, the concentration dependence of the work of adhesion degenerates with increasing molecular weight. Despite their reduced adsorption capacity, the specific geometry of branched PVA macromolecules provides effective steric stabilization of micrometer-sized particles during styrene suspension polymerization. These results demonstrate that chain branching in PVA is a powerful tool for tuning its adsorption properties, stabilizing ability, and interfacial activity. Full article

Tropical lignocellulosic residues are increasingly relevant feedstocks for lignin-containing nanocellulose composites, but their performance cannot be predicted from botanical origin or bulk lignin percentage alone. This review defines the interface as the geometrical boundary between phases and the interphase as the finite, compositionally graded region in which lignin distribution, nanocellulose morphology, adsorbed water, and the surrounding matrix jointly govern stress transfer and mass transport. Using an evidence-weighted framework, the literature is organized into the following categories: residual-lignin nanofibrils, redeposited-lignin systems, lignin nanoparticle assemblies, compatibilized thermoplastic hybrids, and all-lignocellulosic sheets. Representative quantitative observations show that controlled residual lignin can the increase water contact angle from approximately 35 degrees to 78 degrees and reduce oxygen permeability by up to 200-fold in nanopapers, while selected PLA/LCNF systems show tensile-strength and modulus increases of 37% and 61%, respectively; however, high or poorly distributed lignin can suppress fibrillation, lower viscosity, weaken gel networks, and reduce reproducibility. The most defensible near-term product windows are packaging layers, grease/oil barrier papers, coatings, paper-like multilayers, and selected porous media. Thermoplastic matrices remain process-sensitive, and biomedical, additive-manufacturing, nano-reactor, and energy-material claims require stronger validation of the extractables, rheology, humidity history, TEA/LCA metrics, and end-of-life behavior. This review, therefore, provides a critical, application-backward roadmap for tropical biorefineries in which interfacial function, wet handling, drying energy, and process integration are assessed together rather than treated as independent variables. The abbreviations used in the abstract are defined as follows: CNFs, cellulose nanofibrils; CNC, cellulose nanocrystals; LCNF, lignin-containing cellulose nanofibrils; LCNCs, lignin-containing cellulose nanocrystals; PLA, poly(lactic acid); PHB, polyhydroxybutyrate; PHAs, polyhydroxyalkanoates; PVA, poly(vinyl alcohol); DESs, deep eutectic solvents; TEA, techno-economic analysis; LCA, life-cycle assessment; ML, machine learning. Full article

Polyvinyl alcohol (PVA)-based hydrogels suffer from insufficient mechanical strength, while aramid nanofibers (ANF) have intrinsic insulation that limits their sensing applications, and the synergistic effect of composite fillers remains underexplored. This study aims to develop a multifunctional PVA/ANF/NaCl composite organohydrogel for high-performance flexible sensors. The gel was fabricated via freeze–thaw crosslinking, solvent exchange and NaCl impregnation, with systematic investigations of its microstructure, mechanical, electrical and multifunctional sensing properties, and a corresponding triboelectric nanogenerator (TENG) and self-powered handwriting recognition system were constructed. Results show that 2% ANF significantly enhances the gel’s mechanical performance, 0.5 M NaCl achieves optimal mechanical-electrical balance, the gel-based sensor exhibits excellent distance, pressure and strain sensing with high cyclic stability, the TENG delivers stable electrical output, and the recognition system achieves 95% accuracy on the test set. This work provides a new material and design strategy for advanced flexible electronic devices. Full article

In recent years, Ultra High-Performance Fiber-Reinforced Concretes (UHPFRCs) have gained significant attention for their applications in structural components, particularly for improving impact resistance and post-cracking behavior. This study explores the behavior of thin Ultra High-Performance Concrete (UHPC) panels reinforced with synthetic fibers, focusing on the potential use of these materials for building façades. Three different synthetic fiber-reinforced mixes were developed, utilizing polyvinyl alcohol (PVA) microfibers, polypropylene (PP) macrofibers, and a hybrid combination of both. These thin, unreinforced panels were subjected to impact testing using a free-falling steel ball to evaluate their mechanical response. The results were analyzed in terms of crack patterns, crack openings, and overall impact resistance. Additionally, numerical analysis was implemented by using the ABAQUS^TM finite element code, in order to predict the panels’ performance under impact, providing a comparison between experimental results and numerical simulations. This investigation highlights the significant contribution of synthetic fibers in enhancing the toughness and impact resistance of UHPC panels, demonstrating their viability for structural applications requiring enhanced durability. Full article

This study presents the development of biocompatible antistatic nanofibrous composite yarns via a scalable AC electrospinning method, incorporating ultrasonicated expanded graphite (uEG) and PEDOT:PSS into polyamide (PA), polyvinyl butyral (PVB), and polyvinyl alcohol (PVA) matrices. TGA confirmed high filler retention during electrospinning. Electrical measurements showed that the addition of uEG and micrographite reduced single-yarn resistance by up to two orders of magnitude compared with neat polymers, yielding normalised resistivities as low as ~10⁵–10⁶ Ω·m and conductivities in the 10⁻⁷–10⁻⁵ S/m range, suitable for antistatic and sensing applications. However, the large filler–fibre size mismatch and highly porous yarn architecture limited the formation of continuous conductive networks, and mechanical tests revealed strength reductions of up to 70–80% at the highest PVB filler loadings. XRD confirmed a reduction in crystallinity with filler addition, PEDOT:PSS enhanced polymer chain nucleation and thus mechanical properties. Cytotoxicity assays demonstrated that uEG, micrographite, and PEDOT:PSS significantly improved cell viability compared with non-crosslinked PVA, with several PVB-based and PVA/uEG composites showing viability statistically comparable to the DMEM control (>70%) while remaining significantly higher than the Triton positive control. Overall, this work establishes an AC-electrospun route to antistatic nanofibrous yarns that combine high filler retention with enhanced biocompatibility. Full article

Background/Objectives: Guided bone regeneration (GBR) in dental applications requires scaffolds that possess balanced mechanical strength, controlled biodegradability, and excellent biological performance; therefore, this study aims to develop and evaluate a multilayered biofunctional dental membrane designed to enhance mechanical, biological, and antibacterial performance. Methods: The multilayered membrane was fabricated using sequential electrospinning and electrospraying techniques to form a polycaprolactone (PCL)/Collagen first layer and a polyvinyl alcohol (PVA)/Collagen/Hydroxyapatite (HAp) second layer, topped with a final electrospray coating of PVA/Amoxicillin. Characterization was performed via SEM, FTIR, and EDS, followed by evaluations of tensile properties, swelling behavior, hydrolytic degradation, in vitro drug release, disk diffusion antibacterial activity against Staphylococcus aureus and Escherichia coli, and 7-day L929 fibroblast cytocompatibility (ANOVA/Tukey, p < 0.05). Results: SEM, FTIR, and EDS analyses confirmed uniform nanofiber morphology, homogeneous HAp distribution, and successful integration of bioactive compounds. The membrane exhibited a maximum tensile strength of 15.17 N, strain of 25.24%, and stress of 2.16 MPa, while swelling reached ~100% within 2 h and degradation stabilized around 4% weight loss after 48 h. Drug release profiles showed a rapid amoxicillin release in the first 50 min, plateauing at approximately 4.5 mg/L by 350 min, with distinct antibacterial inhibition zones, and the PCL/Col–PVA/Col/HAp–PVA/Amox group demonstrated the highest cell viability (~140%) after 7 days, significantly exceeding the control groups (p < 0.01). Conclusions: These quantitative findings validate the fabricated multilayered membrane’s potential as a mechanically robust, biodegradable, antibacterial, and bioactive scaffold for advanced guided bone regeneration in dental applications. Full article

Polyvinyl alcohol (PVA) and hydroxypropyl methylcellulose (HPMC) films plasticized with glycerin or polyethylene glycol (PEG) were investigated to elucidate structure–property relationships in hydrophilic polymeric film systems. Films were prepared by solution casting at a fixed polymer concentration of 2.7% w/w with plasticizer contents ranging from 0.49 to 1.33% w/w, yielding continuous, free-standing films with good surface integrity. Polymer type and plasticizer dosage strongly affected film breakdown behavior. HPMC films with high plasticization swelled and disintegrated. Effective plasticization was shown by a steady drop in tensile strength and elastic modulus and a significant rise in elongation at break. PVA films plasticized better than HPMC films in PEG-containing solutions. Fourier transform infrared spectroscopy verified hydrogen bonding-driven polymer–plasticizer interactions, with glycerin outperforming PEG. Increasing plasticizer percentage reduced crystallographic order and thermal transition temperature in X-ray diffraction and differential scanning calorimetry. Scanning electron microscopy indicated smooth and uniform surfaces at intermediate plasticizer levels, but variability at higher loadings. Among the studied formulations, PVA films containing 1.33% w/w plasticizer and HPMC films containing 1.05% w/w plasticizer provided the most balanced combination. These findings support physiochemically rational PVA and HPMC film design for pharmaceutical applications. Full article

This study developed high-performance, biodegradable nanocomposites from polyvinyl alcohol (PVA) reinforced with nanocellulose derived from the invasive Nile rose plant (NR). Cellulose nanofibrils (CNFs) were successfully extracted using maleic anhydride treatment, yielding nanofibers with an average diameter of 20.81 nm and a high negative surface charge of −40.7 mV, indicating effective functionalization. The synergistic effect of incorporating 7.5% CNF and applying 50 kGy gamma irradiation dramatically enhanced the composite properties, resulting in a 64.01% improvement in tensile strength compared to neat PVA. The crosslinked network significantly increased hydrophobicity, with the water contact angle rising from 60.95° to 106.40°, and reduced moisture absorption. Optical characterization demonstrated excellent UV-shielding capabilities, maintaining a visible light transmittance of 66.6% at 800 nm, while thermal analysis confirmed enhanced stability against high-temperature degradation. These findings suggest that the developed nanocomposites are promising candidates for advanced protective packaging applications where UV shielding and moisture resistance are critical. Full article

Conductive hydrogels are functional materials that combine soft, highly hydrated properties with electrical signal transmission capabilities. Their conductivity arises from ionic or electronic pathways, and the key design challenge is achieving good conductivity and long-term stability without compromising mechanical performance and biocompatibility. Among various conductive components, conductive polymers have attracted considerable attention due to their tunable mechanical properties, high electrical conductivity, good biocompatibility, and facile synthesis routes. In this study, a series of conductive hydrogels were rationally designed and fabricated by copolymerizing acrylamide and N,N′-methylenebisacrylamide with functionalized poly(vinyl alcohol) (PVA) and poly(3,4-ethylenedioxythiophene-co-thiophene) [P(EDOT-co-Th)]. The functionalized PVA provided multiple dynamic hydrogen-bonding sites, significantly enhancing the toughness of the hydrogel and its adhesion to various substrates, while the P(EDOT-co-Th) copolymer imparted good and stable electrical conductivity. By systematically adjusting the amount of functionalized PVA, the mechanical strength, adhesiveness, and durability of the conductive hydrogels were effectively optimized. The optimized hydrogel exhibited robust adhesion to a wide range of surfaces, excellent fatigue resistance, and long-term stability under repeated mechanical deformation. Moreover, the combination of mechanical resilience and good conductivity enabled precise and reliable signal transduction, highlighting its strong potential as a next-generation material for wearable strain and pressure sensors. Full article

Ionic thermoelectric (i-TE) materials have attracted increasing attention for low-grade heat harvesting owing to their high thermovoltage output under small temperature gradients. However, the development of n-type i-TE materials remains challenging. Electrode-enabled polarity regulation provides a promising alternative to material-design strategies for developing n-type i-TE devices. In this work, a poly(vinyl alcohol) (PVA)-based ionic hydrogel was prepared with dimethyl sulfoxide (DMSO) and potassium chloride (KCl) through a freeze–thaw process, and its thermoelectric behavior was regulated by electrodes. While the i-TE hydrogel device with typical Cu electrodes exhibited p-type behavior, replacing the electrodes with graphite paper (GP) electrodes converted the device response from p-type to n-type. Morphological and spectroscopic analyses suggest that the GP surface selectively adsorbed K⁺ ions through cation–π interactions, suppressing cation thermodiffusion and enabling Cl⁻-dominated ion migration under a temperature gradient. As a result, the PVA-GP device achieved a maximum S_i of −4.36 ± 0.26 mV K⁻¹. In addition, the device exhibited favorable thermoelectric output, with a maximum PF_i of 57.668 μW m⁻¹ K⁻², a room-temperature ZT of 0.0864, and a peak transient power density of 2.33 mW m⁻² during short-time discharge. Owing to the large interfacial area of the GP electrodes, the device could also function as an ionic thermoelectric supercapacitor with appreciable energy-storage capability. This work demonstrates an effective electrode-engineering strategy for constructing n-type i-TE devices and provides a feasible route for simultaneous low-grade heat harvesting and transient energy storage. Full article

Nanoimprint lithography (NIL) is highly dependent on imprinted film as a pattern-transfer medium. This paper systematically reviews the research progress of imprint film materials for NIL. Firstly, polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), polyvinyl alcohol (PVA) and other single-polymer films are discussed, and their respective advantages (such as low surface energy, high optical transparency, water solubility) and inherent limitations (elastic deformation, demolding difficulties, humidity sensitivity)) are summarized. In order to overcome the above contradiction, researchers developed a composite imprint film structure, including an elastomer–rigid bilayer template and sandwich structure film, which achieved high resolution, conformal contact and facile demolding characteristics through mechanical function decoupling. At the same time, the emerging polymer/transparent electrode composite system (such as AgNWs/PVA, AgNWs/PDMS) gives the film active functions such as self-heating and antistatic ones, which effectively solves the key challenges in thermal management and electrostatic control. This paper comprehensively presents the evolution path from single-material to multi-functional composites, and provides guidance for the design of advanced imprint film for high precision, high reliability and large-scale NIL applications. Full article

In this study, a polyvinyl alcohol/carboxymethyl chitosan (PVA/CCTS) hydrogel was synthesized via free radical polymerization and employed for the adsorption of Rhodamine B (RhB) from aqueous solution. The hydrogel was systematically characterized by FTIR, SEM, XPS, and BET analyses, confirming its interconnected porous network and functional group composition. Under optimized conditions (adsorbent dosage = 0.1 g, pH = 6, RhB concentration = 65 mg·L⁻¹, and T = 298.15 ± 2 K), the maximum adsorption capacity reached 15.88 mg·g⁻¹. Kinetic analysis showed that the pseudo-second-order model best described the adsorption behavior under optimal conditions, indicating that the uptake of RhB is governed by multiple interaction mechanisms rather than simple physisorption alone. The equilibrium data were best fitted by the Freundlich isotherm (R² = 0.976), indicating surface heterogeneity of the hydrogel. Thermodynamic evaluation revealed an endothermic (ΔH = 28.38 ± 4.40 kJ·mol⁻¹), with adsorption efficiency improving at elevated temperatures. The hydrogel retained appreciable adsorption capacity after three adsorption–desorption cycles (5.78 mg·g⁻¹ at the third cycle). Density functional theory (DFT) calculations identified -COOH and -NH₂ groups as the primary active sites, and molecular electrostatic potential analysis confirmed that electrostatic interactions between the negatively charged hydrogel surface and cationic RhB drive the initial adsorption. Molecular dynamics (MD) simulations over 100 ns further demonstrated that van der Waals forces constitute the dominant driving force, supplemented by electrostatic interactions and hydrogen bonding, with the hydrogel’s cross-linked network stabilizing adsorbed RhB molecules. The integrated experimental computational approach provides a comprehensive mechanistic understanding of RhB adsorption on PVA/CCTS hydrogel, offering guidance for the rational design of polysaccharide-based adsorbents for dye-contaminated wastewater treatment. Full article

The emergence of multifunctional wound dressings represents a significant transformation in the care of cutaneous tissue injuries, providing advanced solutions that surpass traditional dressings. This study is poised to fabricate multifunctional hydrogels through dual-dynamic cross-linking, integrating antibacterial and antioxidant properties, which are capable of accelerating wound healing while improving therapeutic outcomes. The hydrogel, which exhibits excellent adhesion, rapid self-healing ability, and on-demand removability, was synthesized employing poly(vinyl alcohol) (PVA)–borax as the backbone, followed by the incorporation of silk fibroin (SF), tannic acid (TA), and chitosan (CS). Total saponins of Panax notoginseng flower buds (PNF) with anti-inflammatory and angiogenic properties were loaded in porous structural materials yielding the PBCTS@PNF hydrogel. The prepared hydrogel exhibited outstanding antioxidant properties and cytocompatibility, along with favorable antibacterial capabilities, achieving inhibition rates of 84.30 ± 2.34% against Escherichia coli (E. coli) and 98.12 ± 0.76% against Staphylococcus aureus (S. aureus), respectively. Animal experiments demonstrated that PBCTS@PNF significantly reduced inflammation and promoted multidimensional tissue regeneration, encompassing re-epithelialization, neovascularization, and hair follicle regeneration, along with ordered collagen matrix organization, leading to substantially accelerated wound healing. The multifunctional PBCTS@PNF hydrogel provides a potent bioengineered therapeutic platform for wound healing management through the synergistic interplay among antibacterial, anti-inflammatory, and tissue regenerative functionalities. Full article

Hydrothermally treated chitosan/polyvinyl alcohol beads (H-CS/PVA) were used as filler material in a fixed-bed column for continuous Cr (VI) removal. The effects of main operational parameters, namely bed height, initial concentration and flow rate, were evaluated in the respective ranges of 2–6 cm, 20–60 mg/L and 2.5–7.5 mL/min. Maximum removal efficiency and adsorption capacity were calculated as 64.2% and 15.53 mg/g, respectively. The corresponding breakthrough curves were analyzed by Yoon–Nelson, Adams–Bohart, Thomas and BDST (Bed Depth–Service Time) models, out of which the highest consistency was achieved with the Yoon–Nelson model for all studied conditions. The adsorbent maintained strong reusability, showing minimal loss (~2.5%) in desorption efficiency across three successive regeneration cycles with 0.1 M NaOH as the eluent. SEM and SEM–EDX analyses confirmed the presence of chromium on the H-CS/PVA surface at an elemental fraction of 1.03% (w.). Furthermore, FTIR and XPS analyses verified the role of amine and hydroxyl functionalities in the complexation and adsorption of Cr (VI). Overall, a column system operated under optimal conditions (H_bed: 6 cm, C₀: 40 mg/L, and column diameter: 2.5 cm) and regenerated three times can efficiently treat 20 L of Cr (VI)-contaminated wastewater, resulting in an associated environmental impact of 0.896 kg CO₂-eq. Full article