Composite Films Research Articles

Enhancing energy storage properties via controlled insulation properties of PVDF-based polymer capacitors

In the realm of energy storage and electrical insulation, this study illuminates the innovative fabrication and consequent properties of polyvinylidene fluoride (PVDF) and polyethylene glycol (PEG800) blend films, synthesized via the casting method. The essence of this research lies in the integration of PEG800 into the PVDF matrix, a strategic move that significantly bolsters the insulation capabilities of the resulting composite, underscored by a dramatic decrease in leakage current from 2.61E-7 A to 3.50E-9 A at an electric field of 50 MV/m. Notably, at an optimal PEG800 mass fraction of 30 %, the composite film unveils an extraordinary energy storage density of 34.6 J/cm3 under the formidable electric field of 650 MV/m. This study not only shows cases the superior energy storage and rapid charge-discharge characteristics, particularly with a discharge time (t0.9) of 66 ns of the 70PVDF/30PEG800 film, but also underscores the potential of such blend films in revolutionizing the design and functionality of polymer film capacitors, marking a significant stride towards sustainable and efficient energy storage solutions.

Composites Based on Electrodeposited WO3 and TiO2 Nanoparticles for Photoelectrochemical Water Splitting.

Photoelectrochemically active WO3 films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at -0.5 V vs. SCE. WO3-TiO2 composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO2 nanoparticles (⌀ 36 nm), mechanically suspended in the solution by stirring. After synthesis, the films were annealed at 400 °C. Structural characterization by XRD showed that the WO3 films exhibit the crystalline structure of a non-stoichiometric hydrate, whereas, in WO3-TiO2, the WO3 phase was monoclinic. The oxidation of tungsten, as revealed by XPS, was W6+ for both materials. Ti was found to exist mainly as Ti4+ in the composite, with a weak Ti3+ signal. The efficiency of the WO3 films and composites as an oxygen evolution reaction (OER) photo-electrocatalyst was examined. The composite would generate approximately three times larger steady-state photocurrents at 1.2 V vs. SCE in a neutral 0.5 M Na2SO4 electrolyte compared to WO3 alone. The surface recombination of photogenerated electron-hole pairs was characterized by intensity-modulated photocurrent spectroscopy (IMPS). Photogenerated charge transfer efficiencies were calculated from the spectra, and at 1.2 V vs. SCE, were 86.6% for WO3 and 62% for WO3-TiO2. Therefore, the composite films suffered from relatively more surface recombination but generated larger photocurrents, which resulted in overall improved photoactivity.

INCREASING THE SHELF-LIFE TROUT FILLETS BY SODIUM CASEINATE-PERSIAN GUM BIOCOMPOSITE FILM INCORPORATED WITH GINGER EXTRACT

The effects of sodium caseinate (SC)-Persian gum (PG) films enriched with Zingiber officinale extract (ZOE) were investigated on the quality of rainbow trout over a 16 day at 4°C. The trout filets were divided to 4 groups as uncoated, coated with SC-PG, SC-PG-1% ZOE and SC-PG-1.5% ZOE. Sensorial, chemical and microbial characteristics of trout samples were evaluated on 0, 4, 8, 12 and 16 days of storage. GC-MS analysis exhibited that ZOE is rich in phenolic compounds including zingiberene and cis-6-shogaol. Active films embedded with 1.5% of ZOE revealed a remarkable decline in bacterial growth over the storage time. Wrapping with SC-PG-1.5%ZOE composite film tended to delay the elevation of thiobarbituric acid and peroxide value. Samples containing 1.5% ZOE were mostly preferred by sensory panelists. Based on the results of the present study, the edible films were suitable candidates for preserving quality properties and extending the shelf life of rainbow trout fillets.

Influence of UV irradiation on the luminescence properties of CsPbBr3 perovskite quantum dots and CsPbBr3 perovskite quantum dots/PVDF composite film—for white LED application

Perovskite quantum dots (QDs) have been widely investigated for their excellent properties such as high color purity in displays, tunable emission wavelength, and high photoluminescence quantum yield. For device applications, improving the stability is an area of interest. In this study, the effects of UV irradiation on the structural and luminescence properties of CsPbBr3 perovskite quantum dots (CPB QDs) excited at 365 nm were investigated. To overcome the effects of UV irradiation, a CPB QDs/PVDF composite flexible film was prepared. It exhibits high structural and optical stability under UV irradiation and emits a highly intense green color. The emission wavelength and intensity were observed for three years, and the stability of the temperature-dependent emission intensity up to 400 K has been reported. In addition, it is stable in water. A white LED, fabricated by integrating a blue LED with CPB QDs/PVDF composite film and red phosphor, produces bright natural white light [(CIE x, CIE y) = (0.3704, 0.3611), and CCT = 4177 K] with a color gamut area coverage of 86.4% of the standard NTSC (1953) color space.&#xD.

Advancement of Electro-Optical Properties through Changes in the Physicochemical Composition of Hybrid Thin Films by Doping Reduced Graphene Oxide into a Sol-Gel Process Solution.

A hybrid thin film was fabricated by doping graphene oxide into a sol-gel solution containing a mixture of zirconium, bismuth, and indium oxide. The thin film was fabricated using a brush coating process. The graphene oxide doping ratios used were 0, 5, and 15 wt%. During the thin film fabrication process, the produced sol-gel solution generates a contractile force due to the shear stress of the brush bristles, resulting in a microgroove structure. This structure was confirmed through scanning electron microscopy analysis, which revealed the clear presence of rGO. Comparing the electrical properties of a zirconium bismuth indium oxide thin film without graphene oxide doping and a thin film doped with 15 wt% graphene oxide, the electro-optical properties were significantly improved with graphene oxide doping. In general, the threshold voltage decreased by approximately 0.42 V. In addition, bandgap measurements confirmed the improved conductivity characteristics with graphene oxide doping. Since this improvement in electro-optical properties is associated with the reduction process due to graphene oxide doping, X-ray photoelectron spectroscopy analysis was performed to assess the intensity change of each element. Based on these observations, hybrid thin films doped with graphene oxide emerge as promising candidates for next generation thin film.

Advancing High-Performance Piezoelectric Nanogenerators: Simple Electric Field Switching for Orientated and Aligned BaTiO3/PDMS Composite.

Barium titanate (BaTiO3) is renowned for its high dielectric constant and remarkable piezoelectric attributes, positioning it as a key element in the advancement of environmentally sustainable devices. Nevertheless, the effectiveness of piezoelectric nanogenerators (PENGs) that integrate BaTiO3 nanoparticles (NPs) and poly(dimethylsiloxane) (PDMS) poses a challenge, thereby restricting their utility in energy harvesting applications. This study presents a direct approach involving the cyclic manipulation of direct current (DC) power supply terminals to achieve unidirectional alignment of BaTiO3 NPs within a PDMS matrix, aiming to enhance the performance of the PENGs. Examination of the morphology and evaluation of diffraction planes, notably (111) and (200), in the aligned BaTiO3 PENGs exhibited well-oriented structures resulting from the repetitive switching between two electrodes, leading to improved piezoelectric properties. The BaTiO3 PENGs manifested notably higher output power (∼15 V and 1.91 μA) in contrast to devices containing randomly distributed polarized BaTiO3-PDMS composite films. The generated power was sufficient to directly operate six light-emitting diodes (LEDs) connected in series, with a collective nominal voltage of around 14 V, encompassing red, green, and blue LEDs. Nanoindentation verified the enhanced piezoelectric characteristics attributed to the alignment, sensitivity to bending, and energy-cohesive effects of clustered BaTiO3 one-dimensional (1D) pillars. These findings suggest a widely applicable technique for aligning and situating nanoparticles vertically within a polymer matrix, exploiting the intrinsic dielectric properties of the nanoparticles through a straightforward electric field switching mechanism.

Preparation of ethylcellulose/technical alkaline lignin composite films using 1,4-Dioxane/water as solvents

The poor solvent power of pure solvent systems to lignin certainly induced the inhomogeneous dispersion of lignin in the composite materials. Here, a 1,4-Dioxane/water binary system is used as the solvent to prepare technical alkaline lignin/ethylcellulose composite films. The tensile strength and elongation at break of optimal sample EC1-AL0.2-GDE0.2 reached 26.8 MPa and 21.4 %, respectively. Also, the wettability, thermal stability, and corrosion resistance were adjusted by the technical alkaline lignin.

Reinforced Nacre-Like MXene/Sodium Alginate Composite Films for Bioinspired Actuators Driven by Moisture and Sunlight.

MXene-based soft actuators have attracted increasing attention and shown competitive performance in various intelligent devices such as supercapacitors, bionic robots and artificial muscles. However, the development of robust MXene-based actuators with multi-stimuli responsiveness remains challenging. In this study, a nacre-like structure soft actuator based on MXene and sodium alginate (SA) composite films is prepared using a straightforward solvent casting self-assembly method, which not only enhances the mechanical performance (tensile strength of 72MPa) but also diversifies the stimuli responsiveness of the material. The composite actuators can be powered by external stimuli from renewable energy sources, from moisture inducing a maximum bending angle of 190 degrees at a relative humidity (RH) of 91%, and sunlight irradiation generating a maximum curvature of 1.45 cm-1 under 100mW cm-2. The feasibility of practical applications, including moisture-responsive flowers and walkers, sunlight-responsive oscillators, and smart switches, is demonstrated through comprehensive experimental characterization and performance evaluation. The work presented here provides insight into the design of robust actuators via the utilization and conversion of environmentally renewable energy sources.

Bifunctional Photothermal Evaporator Based on an MXene/Fe-MOF Collaborative Effect toward Efficient Solar Steam Generation and Simultaneous VOC Removal.

Solar-driven interfacial water evaporation has become one of the most promising approaches to effectively harvesting freshwater, yet the fabrication of high-performance and multifunctional solar interfacial evaporators (SIEs) still remains a huge challenge to date. In this study, a multifunctional MXene and Fe-MOF@cellulose acetate/polyvinylpyrrolidone (MXM@CP) SIE was prepared via a facile "electrospinning and suction filtration deposition" coupling strategy. Thanks to the incorporation of MXene, MXM@CP displayed excellent photothermal conversion performance. Together with the fast water transport channel provided by the porous cellulose acetate electrospinning substrate, a remarkable solar-driven water evaporation property was achieved for MXM@CP, showing a higher water evaporation rate of 1.1 kg m-2 h-1 under one sun irradiation. Moreover, the resultant composite film also exhibited excellent Fenton catalytic activity to effectively degrade volatile organic compounds (VOCs) due to the synergistic effect of the MXene and Fe-based MOF (Fe-MOF). Particularly, a relatively higher degradation rate of 82.8% was acquired for the resulting evaporator toward the benzene contaminant. These results provide new insights into the construction of high-performance and multifunctional SIEs toward clean freshwater collection from the VOC-contaminated water system.

Hierarchical nickel phosphide/carbon nanofibers for high performance pseudocapacitors

Nickel phosphide (Ni3P)/Carbon nanofibers (CNFs) with controllable sizes and morphologies are synthesized using micro arc oxidation method combined with thermochemical vapor deposition, with adjustment of different annealing temperatures to control the dimension of CNFs. In this study, we report the in situ formation of transition metal phosphide nanoparticles through the conversion of 1D Ni5TiO7 nanowires. This fabrication strategy ensures the high growth density of CNFs. The initially formed Ni3P nanoparticles boost the catalytic growth of CNFs, which feature a high specific surface area and excellent conductivity. Together with redox electrolyte, the specific capacitance of Ni3P/CNFs based pseudocapacitor (PC) is 114.6 mF cm−2 at a scan rate of 10 mV s−1 and maintains 95.0 % of initial capacity after 10,000 cyclic charging/discharging test. Moreover, such composite based symmetric PCs offer an energy density of as high as 31.6 Wh kg−1 accompanied with a power density of 10.3 kW kg−1. The performance of formed PC devices is comparable to market-available (Li-/Na-) batteries. Therefore, Ni3P/CNFs composite film is a suitable capacitor electrode material for constructing high performance symmetric carbon material based PCs.

Excellent facile fabrication of PVA and lignin nanoparticles from wheat straw after novel DES-THF pretreatment

The utilization of environmental friendly and renewable materials has received increasing attention recently. Lignin nanospheres (LNPs) prepared from recovered lignin and residual lignin after DESs and DESs-THF pretreatment were obtained by self-assembly in the present research. Then, films were prepared by incorporating them into polyvinyl alcohol (PVA) solution. The properties of various films were characterized and compared. Results showed that as the LNPs content increased, the UV blocking capacity of the films was gradually enhanced than PVA film. The DES-THF films showed better antioxidant properties up to 69 % due to higher phenolic hydroxyl content. The hydrophobicity of films incorporated with DESs-THF pretreated lignin was consistently better than that of DES pretreated. DES-THF-M films showed a higher Tmax than that of DES-M films, resulting in better thermal stability. Moreover, DES-THF-L films are lighter in color due to a lower degree of condensation, which is favorable to subsequent applications. The incorporation of LNPs improved mechanical and antioxidant properties, thermal stability, and UV shielding ability of PVA films, especially lignin after DES-THF pretreatment. In conclusion, the prepared PVA/LNPs composite films possessed good functional properties that make them potential for packaging materials.

Unlocking superior preservation: The synergy of lignin and zeolite in chitosan-based composite films for perishable foods

Chitosan-based films are confronted with several technical challenges that impede their broad application in the preservation of perishable foods, such as suboptimal mechanical properties and insufficient antioxidant activity. In this work, we have introduced lignin (LG) and natural clinoptilolite zeolite (NCZ) into pure chitosan-based films to address the above limitations. The synergistic incorporation of LG and NCZ has endowed the composite films, designated as CTSLC, with a suite of enhanced attributes, including improved thermostability, enhanced UV-shielding capability and hydrophobicity, augmented antioxidant activity, refined gas selectivity, and bolstered mechanical properties. The enhancements in the antioxidant activity, gas selectivity, and mechanical properties of CTSLC are notably pronounced, reflecting a substantial advancement in their overall performance. These attributes surpass those of both pure chitosan-based film or commercial polyethylene film. Consequently, CTSLC could keep the freshness and appearance of strawberries and mangoes at least 60 hours and 10 days, respectively. The findings suggest that CTSLC has the potential to be a promising material for the preservation of perishable foods, offering a significant advancement in the field of food packaging and preservation technology.

Rubber seed shell as low-cost medium to produce lactic acid using Lactobacillus plantarum LB2 and fabrication of a polylactic acid-chitosan composite for fish fillet packing

Rubber seed shell (Hevea brasiliensis) was used as a low-cost substrate to produce lactic acid via Lactobacillus plantarum LB2. The medium components were initially screened by two-level full factorial design. Three variables (pH, moisture, and polyoxyethylene sorbitan monooleate (PSM)) were used in the central composite design and response surface methodology. The amount of PSM was found to be a significant variable in lactic acid production. Lactic acid was purified and used for the chemical fabrication of a polylactic acid-chitosan composite film. Compared with the polylactic acid, the composite film improved the tensile strength, elongation strength, and tearing strength. The film prepared with 1% chitosan-polylactic acid exhibited the maximum antibacterial activity against Bacillus cereus (21 ± 1 mm) and the lowest activity against Escherichia coli (10 ± 1 mm). The polylactic acid-chitosan film prepared with 1% chitosan was used as a packing material to store the fish fillets and presented reduced mesophilic (4.3 ± 0.1 Log CFU/g) and psychrotropic (3.2 ± 0.2 Log CFU/g) bacterial populations compared with those of the control (4.9 ± 0.2 Log CFU/g and 3.7 Log CFU/g). Rubber seed shells can be used as an alternative culture medium for lactic acid production, to reduce the production cost of polylactic acid.

Enhancing PVA mulching films: Leveraging modified lignin as a bio-based crosslinking agent for improved mechanical strength, UV barrier, and biodegradability

In contemporary agriculture, eco-friendly mulching films present a promising alternative to conventional plastic mulching films. However, their potential is constrained by challenges related to limited biodegradation and barrier performance. Addressing these limitations, innovative lignin-carboxylated materials were employed as bio-based crosslinking agents to enhance diverse properties in the fabrication of PVA films. Alkali lignin was modified with diethylenetriaminepentaacetic acid (DTPA) to enhance its chemical reactivity. The abundance of carbonyl groups in modified lignin (Lig-DTPA) plays a significant role in establishing strong compatibility with PVA through covalent bonds. This interaction yielded remarkable enhancements, elevating both tensile strength and tensile modulus by an impressive 50.9 % and 60.1 %, respectively. The introduction of Lig-DTPA at 3 % into the PVA composite films resulted in excellent UV-blocking properties. Moreover, at 3 % ratios, the presence of lignin became visibly dispersed as clear spots across the film, indicating a relatively uniform state within the matrix. The study revealed a direct correlation: as the lignin content increased, the film exhibited heightened water solubility and enhanced biodegradability. The PVA/Lig-DTPA film displays promising potential for utilization as a mulching film material, offering anti-ultraviolet functionality and a high degradation rate. Furthermore, its versatility extends to potential applications in packaging materials, including seedling bowls, transplanting pots, and coating films for transportation purposes.

Burst plasma preparation of metallic nanoparticles on carbon fabrics for antibacterial and electrocatalytic applications

Metal nanoparticles have extraordinary properties, but their integration into mesostructures has been challenging. Producing uniformly dispersed nanoparticles attached to substrates in industrial quantities is difficult. Herein, a “plasmashock” method was developed to synthesize metal nanoparticles anchored on different types of carbonaceous substrates using liquid salt solution precursors. These self-supporting, nanoparticle-loaded carbon fabrics are mechanically robust and have been tested as antibacterial substrates and electrocatalysts for reducing carbon dioxide and nitrite. A piece of silver–carbon nanotube paper with a silver loading of ~0.13 mg cm−2 treated after a few-second plasmashock presents good antibacterial and electrocatalytic properties in wastewater, even after 20 bactericidal immersion cycles, due to the strong bonding of the nanoparticles to the substrate. The results prove the effectiveness of this plasmashock method in creating free-standing functional composite films or membranes.

Chitosan/pre-gelatinized waxy corn starch composite edible orally disintegrating film for taurine delivery

In this study, chitosan/per-gelatinized waxy corn starch composite edible orally disintegrating films (ODFs) incorporated with taurine were prepared and the morphology, release behavior and storage stability of the ODFs were investigated. The XRD, ATR-FTIR and microscopic investigation results revealed that taurine could be uniformly dispersed in the film matrix. The optimal level of taurine addition was 1.0% (w/w). The incorporation of taurine improved the apparent morphology, mechanical properties and water holding capacity while slightly increased the film thickness, disintegration time and contact angle of the composite films. In addition, taurine exhibited a rapid release behavior in the films. The fitted results of the Ritger-Peppas model indicated that the release mechanism of taurine in the composite films was mainly Fickian diffusion with minor skeleton erosion. As a delivery carrier, the composite film had a positive effect on the preservation of taurine, increasing the retention of taurine by 8.34% ± 1.48% during storage. The study confirmed the feasibility for the development of taurine ODF carriers and provided a basis for the development of functional packaging materials.

Food simulants affected the migration of essential oil and film structure in chitosan based composite films

Food simulants affected the migration of essential oil and film structure in chitosan based composite films

Characterization of exopolysaccharide / starch composite film incorporated with TiO2 nanoparticles and its application in chilled meat preservation

Multifunctional food packaging composite films were prepared using Pediococcus acidilactici J1 exopolysaccharide (EPS), potato starch (PS) and TiO2 nanoparticles by casting method. The microstructure, physicochemical properties and antibacterial activity of EPS/PS composite films with different weight ratio of TiO2 nanoparticles were characterized. Transmission electron microscope (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed the uniform distribution of TiO2 nanoparticles in the EPS/PS matrix. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) results indicated that the interaction between polymers and nanoparticles through non-covalent bonds. When TiO2 nanoparticles were added at 1 % (wt), the composite film had higher barrier properties against water vapor and UV–vis light, and better mechanical properties then EPS/PS film. Notably, EPS/PS/1%TiO2 composite film exhibited good antioxidant and antibacterial activity against Escherichia coli and Staphylococcus aureus. Through the analysis of the quality indexes and microbial community structure during the storage of chilled meat, the composite film slowed the oxidation rate of chilled meat and inhibited the growth of dominant spoilage bacteria, effectively extending its shelf life. All results suggested that EPS/PS/1%TiO2 composite film could serve as an effective packaging material for chilled meat, providing a novel approach to solve its limited shelf-life problem.

Fabrication of bamboo nanocellulose fibril-based food packaging with dual-antimicrobial property

The development of cellulose-based packaging films with excellent antimicrobial properties and biocompatibility has garnered significant attention. In this work, nanocellulose fibrils (NCFs) derived from from bamboo parenchyma cells were utilized to fabricate nanocomposite film with antimicrobial properties. This system exhibited distinct release behaviors for two antimicrobial agents, with the slow release of Ag nanoparticle (AgNP) in the initial stage contributed to delaying food spoilage, while the subsequent pH change in the microenvironment facilitated the release of essential oil of sour orange blossoms (SEO) for secondary antimicrobial activity. Additionally, the composite film demonstrated improved thermal stability and UV blocking capacity. Moreover, AgNP has been proven to enhance the mechanical properties, with the tensile strength of the novel composite film increasing by 34.85 % compared to control group. The water vapor permeability and oxygen permeability of the novel composite film were reduced, which could potentially reduce weight loss and slow down the rate of after-ripening. Following the acidification treatment, the films containing EO@MPN (essential oil encapsulated with metal-polyphenol network) component performed different antimicrobial patterns, indicating their pH-responsive antimicrobial capabilities, and they are effective against both Gram-positive and Gram-negative bacteria. After a 24-h exposure to a food simulant, the release amount of Ag was measured at 67.6 μg/dm2, within the acceptable limit, and the release profile of Ag was characterized. Cytotoxicity and Live/Dead staining tests confirmed that the novel composite film film had no significant toxicity, thus making it safe for application in food preservation. Furthermore, in a 15-day preservation experiment with mangoes, the novel composite film demonstrated the best performance, underscoring its potential as a sustainable antimicrobial packaging material.

Mechanoluminescent/Electric Dual-Mode Sensors Enabled by Trace Carbon Nanotubes.

Mechanoluminescence (ML)-based sensors are emerging as promising wearable devices, attracting attention for their self-powered visualization of mechanical stimuli. However, challenges such as weak brightness, high activation threshold, and intermittent signal output have hindered their development. Here, a mechanoluminescent/electric dual-mode strain sensor is presented that offers enhanced ML sensing and reliable electrical sensing simultaneously. The strain sensor is fabricated via an optimized dip-coating method, featuring a sandwich structure with a single-walled carbon nanotube (SWNT) interlayer and two polydimethylsiloxane (PDMS)/ZnS:Cu luminescence layers. The integral mechanical reinforcement framework provided by the SWNT interlayer improves the ML intensity of the SWNT/PDMS/ZnS:Cu composite film. Compared to conventional nanoparticle fillers, the ML intensity is enhanced nearly tenfold with a trace amount of SWNT (only 0.01wt.%). In addition, the excellent electrical conductivity of SWNT forms a conductive network, ensuring continuous and stable electrical sensing. These strain sensors enable comprehensive and precise monitoring of human behavior through both electrical (relative resistance change) and optical (ML intensity) methods, paving the way for the development of advanced visual sensing and smart wearable electronics in the future.