Polyvinyl Alcohol Films Research Articles

Polyvinyl Alcohol Films Reinforced with Nanocellulose from Rice Husk

Polyvinyl Alcohol Films Reinforced with Nanocellulose from Rice Husk

Synergistic Nitrate Removal: Enhanced Efficiency with Zinc-Immobilized Calcium Cross-Linked Polyvinyl Alcohol Film

Nitrate is a major water contaminant causing eutrophication and poses health risks. Controlling its levels is essential. In this study, zinc powder immobilized calcium cross-linked polyvinyl alcohol (Zn-Ca-PVA) film was synthesized for the removal of nitrate from water samples. The results demonstrated an enhanced removal efficiency, increasing from 47.82% ± 1.14% for the film without zinc powder to 78.47% ± 5.20% with a maximum adsorption capacity of 9.56mgg−1 when using Zn-Ca-PVA with synthetic water samples. This enhancement suggests a synergistic mechanism in which nitrate is adsorbed onto the calcium cross-linked PVA film via electrostatic interaction, and then catalytically reduced by the zinc powder within the film, converting it into nitrogen-containing gas and removing it from the sample. Moreover, this synergistic approach resulted in high removal efficiencies for real water samples, ranging from 82.95% ± 0.98% to 96.19% ± 0.62%. The adsorption of nitrate aligned well with the Freundlich model, while the kinetic process aligned well with the pseudo-second-order model (R2 > 0.99). Thermodynamic studies revealed ΔG° values ranging from -2.71 to -3.76kJmol−1, ΔH° of 6.22kJmol−1, and ΔS° of 29.98Jmol–1 K–1, indicating spontaneous adsorption, an endothermic nature, and increased randomness at the solid/solution interfaces during nitrate adsorption. Furthermore, Zn-Ca-PVA exhibited tolerance to coexisting ions, with the removal efficiency of nitrate remaining largely unchanged (< 5%) even in the presence of mixed coexisting ions at five times higher concentrations. These findings highlight the promising potential of Zn-Ca-PVA films for practical applications in nitrate removal.

Colloidal phenomena upon tensile drawing of polyvinyl alcohol films in the vegetable oil: Structural and applied aspects

Colloidal phenomena upon tensile drawing of polyvinyl alcohol films in the vegetable oil: Structural and applied aspects

Preparation and characterization of polyvinyl alcohol and chitosan composite film with cassia oil encapsulated in β-cyclodextrin and its application in fresh banana.

In this study, composite films were developed by encapsulating cassia oil (CO) with β-cyclodextrin through a microencapsulation technique and incorporating it into a chitosan (CS), polyvinyl alcohol (PVA) and glycerol matrix. The primary objective of the film was to inhibit bacterial growth on the surface of fresh bananas and extend their shelf life. Characterization methods were employed to evaluate the physical properties and functionality of the composite films. FTIR, XRD, and SEM analyses demonstrated that cassia oil microcapsules (COM) were uniformly dispersed throughout the film and exhibited excellent compatibility with the matrix. The inclusion of 30 % COM improved the film's UV-blocking properties from 86.15 % to 91.03 %. Additionally, due to its hydrophobic nature, CO significantly reduced the water content to 9.02 % and 10.67 %. Furthermore, the COM enhanced the film's tensile strength from 21.18 MPa to 43.21 MPa, and increased its antioxidant capacity to 36.87 %. The results also indicated that 30 % COM significantly enhanced the film's antimicrobial activity against Escherichia coli and Staphylococcus aureus with inhibition zone diameters of 12.5 mm and 11.5 mm, while maintaining biosafety, as evidenced by unaltered cell survival rates in BEAS-2B and L02 cells. The film containing 30 % COM exhibited excellent preservation capacity for bananas, effectively extending their shelf life. These findings suggest that films containing COM have the potential to replace traditional plastic packaging in practical applications.

Development of a Sustainable Flexible Humidity Sensor Based on Tenebrio molitor Larvae Biomass-Derived Chitosan.

This study presents the fabrication of a sustainable flexible humidity sensor utilizing chitosan derived from mealworm biomass as the primary sensing material. The chitosan-based humidity sensor was fabricated by casting chitosan and polyvinyl alcohol (PVA) films with interdigitated copper electrodes, forming a laminate composite suitable for real-time, resistive-type humidity detection. Comprehensive characterization of the chitosan film was performed using Fourier-transform infrared (FTIR) spectroscopy, contact angle measurements, and tensile testing, which confirmed its chemical structure, wettability, and mechanical stability. The developed sensor exhibited a broad range of measurements from 6% to 97% relative humidity (RH), a high sensitivity of 2.43 kΩ/%RH, and a rapid response time of 18.22 s with a corresponding recovery time of 22.39 s. Moreover, the chitosan-based humidity sensor also demonstrated high selectivity for water vapor when tested against various volatile organic compounds (VOCs). The superior performance of the sensor is attributed to the structural properties of chitosan, particularly its ability to form reversible hydrogen bonds with water molecules. This mechanism was further elucidated through molecular dynamics simulations, revealing that the conductivity in the sensor is modulated by proton mobility, which operates via the Grotthuss mechanism under high-humidity and the packed-acid mechanism under low-humidity conditions. Additionally, the chitosan-based humidity sensor was further seamlessly integrated into an Internet of Things (IoT) framework, enabling wireless humidity monitoring and real-time data visualization on a mobile device. Comparative analysis with existing polymer-based resistive-type sensors further highlighted the superior sensing range, rapid dynamic response, and environmental sustainability of the developed sensor. This eco-friendly, biomass-derived, eco-friendly sensor shows potential for applications in environmental monitoring, smart agriculture, and industrial process control.

Modulating room-temperature phosphorescence of D-π-A luminogens via methyl substitution, positional isomerism, and host-guest doping.

Organic room-temperature phosphorescence (RTP) luminogens have showed significant potential in the fields of diagnostics, sensing, and information encryption. However, it is difficult to achieve high RTP yield (ΦP) and long RTP lifetime simultaneously. By methyl substitution, positional isomerism, and host-guest doping, three new D-π-A type luminogens named as TBTDA, 2M-TBTDA, and 3M-TBTDA were designed and synthesized, whose RTP properties were tuned and optimized. In various solvents and glassy THF solution, similar solvatochromism and phosphorescence nature of three luminogens were revealed. In poly (methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA) matrixes, the luminogens showed high-contrast RTP properties. TBTDA emitted invisible afterglow in PMMA films, but with strong RTP and long green afterglow in PVA films. More importantly, 2M-TBTDA showed RTP and afterglow lifetimes of 809.81ms and 8s, as well as ΦP of up to 0.64 in PMMA at 1% doping concentration. Taking advantage of Foerster resonant energy transfer (FRET), reddish-brown or orange afterglow were observed, with emission maxima of 593-617nm, RTP and afterglow lifetimes of 299-566ms and 5-6s, ΦP of 0.34-0.46, as well as FRET efficiency of 70-90%. Finally, dynamic anti-counterfeiting and digital encryption were successfully constructed via different fluorescence, RTP colors, and afterglow lifetimes. This work not only obtained an efficient host-guest doping RTP system, but also can be expected to provide more theoretical guidance and experimental supports for molecular design, dynamic anti-counterfeiting and digital encryption.

Luminescence Properties of Hoechst 33258 in Polyvinyl Alcohol Films.

We report a comprehensive investigation of the photophysical properties of Hoechst 33258 (HOE) embedded in polyvinyl alcohol (PVA) films. HOE displays a bright, highly polarized, blue fluorescence emission centered at 430 nm, indicating effective immobilization within the polymer matrix of PVA. Its fluorescence quantum yield is notably high (~0.74), as determined relative to a quinine sulfate standard. In addition, we observed that HOE-doped PVA films exhibit room temperature phosphorescence (RTP) that remains visible for several seconds after UV excitation ceases. The slightly negative phosphorescence anisotropy implies that the triplet-singlet radiative transition is orthogonal to the singlet-singlet transition governing fluorescence. Notably, we observed that direct triplet-state excitation at longer wavelengths (beyond the primary absorption band) produces highly polarized RTP. We believe this possibility of direct triplet-state excitation opens new avenues for studying RTP in polymer-immobilized molecules.

Multifunctional electrospun nanofiber films of polyacrylonitrile and polyvinyl alcohol incorporating rhamnose and therapeutic agents for enhanced healing of infected burn wounds

Infected burn wounds present significant clinical challenges due to delayed healing and risk of infection, necessitating advanced treatments that offer both antimicrobial and regenerative properties. This study aimed to develop and evaluate multifunctional electrospun nanofiber films incorporating rhamnose (as an angiogenic agent) and therapeutic agents, namely fluticasone, mupirocin, ciprofloxacin, and silver sulfadiazine, for the enhanced healing of infected burn wounds. Nanofibers containing rhamnose, polyacrylonitrile, polyvinyl alcohol and therapeutic agents were fabricated via electrospinning. The nanofibers were characterized chemically and biologically. FTIR confirmed successful drug incorporation, while XRD indicated a reduced crystallinity in drug-loaded nanofibers. SEM analysis revealed bead formation in some formulations. MTT assays demonstrated moderate cytotoxicity, with formulations F2 (containing all components) and F4 (containing all components except silver sulfadiazine) showing enhanced activity due to rhamnose. Antibacterial studies indicated superior efficacy of formulations F1 (containing all components except rhamnose) and F2 against Staphylococcus aureus and Klebsiella pneumoniae, while anti-inflammatory assays highlighted strong ROS inhibition by formulations containing rhamnose. In vivo wound healing studies for 14 days showed faster wound closure and reduced scarring in groups treated with nanofiber formulations F1-F4, particularly those containing multiple active agents, achieving up to 30% faster healing than the control group. The multifunctional nanofibers exhibited promising antimicrobial, anti-inflammatory, and wound-healing properties, making them potential candidates for treating infected burn wounds. Further studies are needed to optimize the formulations for clinical.

Thermal Stability and Electrical Conductivity of Polyvinyl Alcohol Composites Reinforced with Mn2O3–rGO

AbstractThe current work is concerned with the study and examination of the thermal and electrical characteristics of polyvinyl alcohol (PVA)/Mn2O3–reduced graphene oxide (rGO) nanocomposite. The Mn2O3–rGO composite was synthesized using a hydrothermal approach technique, and then PVA films were strengthened with varying amounts of Mn2O3–rGO nanoparticles (NP) prepared by the casting method. Raman analysis was applied to polymer films to ensure the complexation between the PVA and Mn2O3–rGO. Thermogravimetric analysis (TGA) and electrical analysis are used to investigate the effect of Mn2O3–rGO NP on the thermal stability and electrical conductivity of the polymer films. The films' thermal stability was raised by increasing the Mn2O3–rGO content in the PVA matrix. The polymer films exhibit an increase in electrical conductivity from 2.023 × 10⁻⁸ S·cm⁻¹ for pure PVA to 1.895 × 10⁻⁵ S·cm⁻¹ for PVA‐1.5% Mn2O3–rGO, which arises from the rise in free charge carrier mobility and hopping ionic hopping. Furthermore, in accordance with the Arrhenius relation, conductivity increases with temperature. The results nominated the present composite in flexible electronic applications.

Influence of additives on the development, mechanical, functional characteristics and biodegradability of banana starch-based bio plastic films.

Starch-based bioplastics, due to their abundance, recyclability, and biodegradability, offer a promising alternative to conventional petrochemical-based plastics. Additives significantly influence the functionality of bioplastics. This study investigates the effects of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) at varying concentrations on banana starch-based bioplastic films, using glycerol as a plasticizer. CMC-based films exhibited higher L* values and thickness (0.51-1.55 mm) compared to PVA films. Due to hydrophilicity, CMC films demonstrated 2-3 times greater solubility (17-23 %) and water absorption (75.29 %). Moisture-rich films, C3 and PC2:1, showed the highest WVTR values of 25.73 and 24.10 g/m2/day, respectively, while PVA-rich films (1-1.5 %) had lower WVTR. Increasing CMC concentration reduced OTR values (2.59-3.58 cm3/m2/day) compared to PVA (4.19-5.23 cm3/m2/day). PVA enhanced transparency and smoother morphology, while CMC imparted texture and fibrous structures. Gloss values ranged from 9.82 (P1) to 40.88 (PC2:1), with CMC films exhibiting 3-4 times higher gloss. Tensile strengths varied from 8.34 MPa (C1) to 24.73 MPa (C2), highlighting CMC's mechanical enhancement, while P1 achieved the highest elongation of 90.23 %. FTIR spectra confirmed banana starch matrices, and CMC's crystalline nature at 2θ = 23° reduced polarity and crystallinity, influencing water absorption. These insights support designing banana starch-based bioplastics for a sustainable future.

In2O3 synthesis and investigation of their impact on the structural and physical characteristics of polyvinyl alcohol films for optical applications

In2O3 nanoparticles were synthesized via the simple-polymerized-complex method and incorporated in the PVA matrix with different contents to obtain PVA-In2O3 films via the casting technique. The optical and structural characteristics of the synthesized PVA-In2O3 films were analyzed using Fourier transform infrared (FTIR), scanning electron microscope (SEM), UV-vis spectroscopy, and X-ray diffraction (XRD). These techniques help in understanding how the addition of In2O3 affects the PVA properties. The change in PVA’s structure upon increasing the In2O3 concentration was investigated through XRD and FTIR. XRD showed the change in the crystallinity of the PVA with increasing In2O3 concentration. SEM confirms the incorporation of In2O3 in the PVA matrix in the nanoscale with the formation of aggregations at higher concentrations. The PVA’s optical absorbance was investigated through the UV-visible spectrophotometer, and a change upon adding In2O3 nanoparticles was observed. The PVA’s direct bandgap changed from 5.41 eV to 3.5 eV, and the indirect bandgap from 4.61 eV to 2.5 eV upon adding 8% In2O3. Increasing In2O3 concentration in the PVA significantly enhances the refractive index and optical conductivity. These results highlight the potential of In2O3-filled PVA films for optical applications, showcasing their improved optical and structural properties.

Synergistic effects of Uncaria gambir and zinc oxide in polyvinyl alcohol films for enhanced UV and blue light shielding, antimicrobial properties, and hydrophobicity: improving application performance in sustainable packaging and protective eyewear.

This study investigates the development and characterization of a novel composite material consisting of polyvinyl alcohol (PVA) integrated with Uncaria gambir (UG) and zinc oxide (ZnO) as fillers. The synergistic effects of UG and ZnO were investigated, focusing on their ability to enhance the film's properties. UV-vis spectrophotometry demonstrated that the composite film effectively blocked all UV (UV-A and UV-B) and blue light wavelengths. The mechanical properties were significantly enhanced, with tensile strength improving by 56% and elasticity by 38% compared to pure PVA. Additionally, water contact angle measurements showed an increase from 34.4° for pure PVA to 84.4° for the PVA/UG/ZnO composites, indicating a substantial improvement in hydrophobicity, which suggests the potential for extended application in environments where moisture resistance is crucial. These findings illustrate the potential of utilizing natural extracts and metal oxides in polymer composites for applications that require durable and effective protection against photodegradation and environmental factors. This study establishes a foundation for further exploration into biocompatible and environmentally sustainable materials with enhanced protective properties.

Highly Sensitive Optical Fiber Humidity Sensor Based on Polyvinyl-Alcohol Film Induced Lossy Mode Resonance

Highly Sensitive Optical Fiber Humidity Sensor Based on Polyvinyl-Alcohol Film Induced Lossy Mode Resonance

Capillary-driven self-assembly of soft ellipsoidal microgels at the air–water interface

The adsorption of ellipsoidal colloidal particles on liquid interfaces induces interfacial deformation, resulting in anisotropic interface-mediated interactions and the formation of superstructures. Soft prolate-shaped microgels at the air-water interface offer an ideal model for studying spontaneous capillary-driven self-assembly due to their tunable aspect ratio, controlled functionality, and softness. These microgels consist of a polystyrene core surrounded by a cross-linked, fluorescently labeled poly([Formula: see text]-isopropylmethylacrylamide) shell. By uniaxially stretching the particles embedded in polyvinyl alcohol films, the aspect ratio [Formula: see text] can be finely adjusted. [Formula: see text] was found to vary from 1 to 8.8 as estimated in their swollen conformation at 20 °C from confocal laser scanning microscopy. The spontaneous interfacial self-assembly at the air-water interface is investigated through fluorescence microscopy, theoretical calculations, and computer simulations. A structural transition occurs from a seemingly random assembly for small aspect ratios to compact clusters, which transform into a side-to-side assembly forming long chains for high aspect ratios. The influence of the poly([Formula: see text]-isopropylmethacrylamide) shell on the assembly indicates a significant [Formula: see text]-dependent microgel deformation. This deformation, in turn, determines the average distance between the particles. Consequently, capillary-driven self-assembly of soft anisotropic colloids becomes a powerful mechanism for structuring interfaces and designing microstructured materials.

Photoresponsive Luminescent Silica Nanoparticles as Additive for 3D Printing and Electrospinning.

In this study, we present the synthesis and a versatile way to incorporate photoresponsive organic luminophores into polymeric materials using mesoporous silica nanoparticles (MSNs). The encapsulated thioethers within the MSNs were employed in polyvinyl alcohol (PVA) films, resin-based stereolithography, and electrospinning. Due to light-induced cyclisation to dibenzothiophenes (DBTs), mmOC12 loaded materials were used to inscribe images using UV light. The DBTs formed from mmOC12 (mmDBTA/B) exhibit a long phosphorescence afterglow, which was investigated by steady-state and time-resolved photoluminescence spectroscopy. In addition, scanning electron microscopy (SEM) imaging, including energy dispersive X-ray spectroscopy (EDX), revealed the well-dispersed and intact MSNs in the polymeric materials. This approach shows a general way to incorporate non-polar organic luminophores into polymeric materials while retaining their unique emission properties.

Linear and Nonlinear Optical Characteristics of Basic Fuchsin-Doped Polyvinyl Alcohol Films for Flexible Optoelectronics

Abstract Polyvinyl alcohol (PVA) containing different levels of basic fuchsine (BF) was prepared using the solution casting method. Characterization via Fourier-transform infrared spectroscopy detailed changes in functional groups within the PVA/BF composites, indicates the hydrogen bonding between OH group of PVA and BF molecules. Optical investigations spanning the 190-2500 nm range demonstrated UV blocking properties in prepared PVA/BF composites (fromn 2.05 to 2.56 eV and from 4.08 to 6.32 eV). Moreover, the studies on optical band gap indicated a decrease with increased BF concentrations, reflecting altered electronic transitions within the prepared composites. The study also employed the single oscillator model provided by Wemple-DiDomenico to elucidate refractive index variations. After incorporating BF dye into the PVA polymer, the values of the dielectric constant as the frequency approaches infinity (ε∞), the dielectric constant of lattice (εL), dispersion energy (Ed), and oscillator energy (Eo) in PVA/BF composite samples showed an increase. Moreover, the nonlinear optical properties, including optical susceptibility and nonlinear refractive index were investigated and discussed. These findings underscore the versatility of PVA doped with BF for various applications including optical filters, and solar cell devices.

Development of an intelligent packaging material incorporating betacyanin from red beetroot extract into polyvinyl alcohol films

This research aimed to develop an intelligent packaging material by incorporating betacyanin from red beetroot extract into polyvinyl alcohol (PVA) film. Betacyanin was extracted using three solvents (Distilled Water, Ethanol, and Methanol), and films were prepared. The methanolic extract had the highest betacyanin content (416.57µg/100g), while the distilled water extract had the lowest (310.22µg/100g). Incorporating betacyanin increased the film thickness, with methanol-extracted films (MEF) being the thickest (126.36µm). Light transmittance differed significantly, being highest in ethanol-extracted films (EEF) (4.32%) compared to control (3.65%) and MEF (3.82%). Water solubility was highest in the control sample (44.94%), and water vapor permeability was lowest in methanol-extracted films (14.25gmsPa-1 × 10-7), indicating better film quality. MEF had the lowest lightness (L*=31.71), while control films had the highest (L*=38.84). The a* value was lowest for control films (a*=1.97) and highest for methanol-extracted films (a*=6.08). EEF had the highest b* value (b*=6.58±0.95), and control films had the lowest (b*=4.01). All films exhibited low mechanical resistance with tensile strengths ranging from 2.84 to 3.16 MPa. Additionally, these films can detect pH changes, acting as promising colorimetric bioindicators. The study concludes that intelligent films made with methanol-extracted betacyanin are viable for developing pH-responsive packaging for the food industry.

The rational design of ratiometric probe based on fluorescence carbon dots and its PVA film platform for the detection of Hg2+: tunable mechanism and the performance

Carbon dots (CDs) are recognized as sensitive probes for the detection of Hg2+ due to their remarkable fluorescent properties and ease of synthesis. However, drawbacks such as high costs, intricate synthesis, and non-portability hinder their broader applications. This study reported the synthesis of tunable multicolor CDs, including blue (B-CDs), green (G-CDs), and orange (O-CDs), by using hydrothermal methods while adjusting precursors and temperature. The observed fluorescence redshift from B-CDs to G-CDs or O-CDs arose from interactions among particle size, sp² conjugation, and surface oxidation, while the redshift from G-CDs to O-CDs was linked to surface fluorophores. Moreover, a ratiometric probe was developed by mixing B-CDs (response signal) and O-CDs (reference signal). Hg2+ significantly quenched B-CDs fluorescence due to static quenching from electron transfer. The probe demonstrated excellent stability and sensitivity, with limits of detection (LOD) of 4.8nM in the 0-0.6μM range and 9.2nM in a broader range (0-50μM). A portable smartphone-assisted detection platform was further developed by integrating the probe into polyvinyl alcohol (PVA) hydrogel. Both methods manifested the capability to accurately quantify Hg2+ in real water samples. This research provides innovative strategies for multicolor CDs and a sensing platform for rapid on-site Hg2+ detection.

Active polyvinyl alcohol films with enhanced strength, antioxidant and antibacterial properties by incorporating nanocellulose and tannin

There is an increasing demand of food packaging materials from sustainable bio- polymers. In this study, tannin-cellulose nanocrystal (TCNCs) fillers were first prepared using dialdehyde cellulose nanocrystal (DACNCs) and tannin through the nucleophilic addition reaction, and then added to PVA matrix as reinforcement fillers to fabricate active food packaging films. FT-IR analysis confirmed the successful reaction between PVA and TCNCs. The incorporation of TCNCs imparted high antibacterial, UV blocking and antioxidant capabilities to the composite films, maximumly achieving a 75 % DPPH free radical scavenging rate while blocking all UV rays. The addition of TCNCs resulted in an increase in water contact angle, alongside decreases in swelling ratio and solubility, indicating the enhanced water resistance. The composite films exhibited a 66.7 % decrease in oxygen permeability (OP) compared to the PVA film, with a slight increase observed in water vapor permeability (WVP). The tensile strength increased from 49.65 MPa to 74.17 MPa by adding 15 % of TCNCs due to the chemical crosslinking between PVA and TCNCs. Wrapping cherry tomatoes with these films prolonged the postharvest life compared to using polyethylene (PE) and pure PVA films. Films derived from sustainable biopolymers show great potential for use in fresh produce packaging.

Beeswax-poly(vinyl alcohol) composite films for bread packaging

The study aimed to improve the barrier characteristics of polyvinyl alcohol (PVA) film by adding beeswax (BW) and glycerin and by heat treatment in order to become a potential suitable material for bread packaging. XRD, FTIR and XPS showed new cross-links between PVA and beeswax demonstrating the composite nature of the film. TGA-DTA showed that glycerin reduced the dehydration and that the beeswax improved theirs thermal stability. The best PVA-beeswax film formula has water vapor permeability (WVP) only 7.5 times higher than that of polyethylene (PE), while PVA is 29 times more permeable. The correlation coefficients, linear (MLR) and stepwise (SR) regression modelling showed a direct correlation between WVP, solubility in food simulants, swelling capacity and biodegradability. Principal Component Analysis (PCA) demonstrated that the analyzed films have different behavior from PE, and among them the most similar is that of the PVA with 2 g of beeswax and no glycerin sample. This film type also showed efficiency in bread packaging.