Composite Films Research Articles

Experimental analysis and ANFIS modeling of optical properties and band gap engineering in Se–Te–Ge film composition and insights into its photonic applications

Experimental analysis and ANFIS modeling of optical properties and band gap engineering in Se–Te–Ge film composition and insights into its photonic applications

Development of Hematite Nano Ellipsoids/Pectin Composite Films for Green Packaging Applications.

Synthetic packaging materials are known to cause serious environmental and human health problems. Among the eco-friendly biopolymers from nonfood sources that are suitable for packaging applications, pectin is a promising candidate. However, native pectin films (NPF) exhibit poor mechanical strength, high hydrophilicity, and poor gas diffusion barrier properties. These shortcomings offset the advantages of pectin as a potential packaging material. To address these limitations, in this study, hematite nano ellipsoids (HNEs) were incorporated as fillers to reinforce native pectin films. This reinforcement resulted in substantial improvements in the mechanical properties, hydrophobicity, thermal stability, barrier properties, and optical attributes of pectin films. Compared to NPF, the pectin-hematite composite film exhibited a 35% increase in tensile strength, a 30° increase in contact angle, a 6-fold increase in the oxygen diffusion barrier properties, and a 20% increase in the water vapor barrier properties. This study presents a sustainable, biocompatible, and biodegradable packaging solution by capitalizing on eco-friendly biopolymer and nanoparticle engineering.

Ultrahigh stability photovoltaic performance of M-Mo6+ (M=Fe3+, Co2+, Ni2+) co-doped BiVO4 films

BiVO4 has been widely studied in photovoltaic conversion. However, as a paraelectric material, BiVO4 lacks an internal electric field for efficient carrier separation, resulting in low photocurrent and limited practical use. Enhancing the photovoltaic performance of thin films through simple methods is challenging. In this paper, M-Mo6+ (M=Fe3+, Co2+, Ni2+) ions were used to co-doped BiVO4 films, which were then composited with NiO to construct composite film structures. The NiO/Bi0.985Co0.015V0.985Mo0.015O4 film achieved a photocurrent density (Jsc) of 2.33 mA/cm2 and an open-circuit voltage (Voc) of 0.39 V. The film also demonstrated a specific detection rate of 2.67 × 1011 jones at an optical power density of 165 mW/cm2 and maintained 1.94 × 1011 jones at 103.7 mW/cm2. At an optical power density of approximately 140 mW/cm2, the specific detection rate begins to decrease. The photovoltaic conversion performance of the film exhibits high stability over a long period of time (＞10,000 s). The thin films maintain good photovoltaic performance at high temperatures. This work provides an approach for the application of BiVO4 in photovoltaics.

Novel Carboxymethyl Cellulose/Gelatin-Based Film Incorporated with Zein-Stabilized Lemon Essential Oil Pickering Emulsion for the Preservation of Cherries.

In this study, a zein-stabilized lemon essential oil Pickering emulsion (ZLPE) was incorporated into a carboxymethyl cellulose/gelatin (CMC/GL) composite film to develop a bio-based packaging material with bioactive properties. The average droplet size of the ZLPE was measured at 3.62 ± 0.08 μm, with a zeta potential of -31.33 ± 0.32 mV, highlighting its excellent stability. The image results of confocal laser microscopy and scanning electron microscopy validated the uniform distribution of ZLPE in the film. The incorporation of ZLPE reduced the water solubility of films by 45.90% and decreased its water vapor permeability by 22.61%, thereby enhancing its hydrophobicity. Additionally, the ZLPE-loaded film improved mechanical properties, enhanced UV-blocking capabilities, and increased thermal stability. The introduction of ZLPE led to the antioxidant activity of the CMC/GL film increasing by six times the original level and endowed it with outstanding antibacterial properties. As a result, cherries packaged with the ZLPE film demonstrated superior preservation performance and extended shelf life in the preservation experiment, exhibiting the film's potential as a food packaging material.

Preparation of zein active films with antimicrobial and antioxidant properties by incorporating gallic acid loaded γ-CD-MOF for pork preservation

The growing concerns over food contamination caused by microorganisms, coupled with the worsening environmental impact of petroleum-based plastics have drawn significant attention to eco-friendly materials in food packaging. Herein, cyclodextrin-metal-organic framework (CD-MOF) was prepared as promising nanocarrier for the natural product gallic acid (GA). Then, the prepared material (GA@CD-MOF) was incorporated into zein matrix to obtain Zein-GA@CD-MOF films. Further studies showed that the composite films possessed great potential for food packaging, offering excellent UV-light blocking, water resistance, and mechanical properties. Notably, Zein-GA@CD-MOF films demonstrated superior antimicrobial activity (44.56%–77.97% against Escherichiacoli O157:H7 and 28.36%–59.49% against Salmonellaenterica) and sustained antioxidant properties for 100 days, which correlated with the sustainable release effect of GA. Furthermore, the exceptional biosafety of GA@CD-MOF has been confirmed through cytotoxicity and hemolysis assays. Pork preservation experiments illustrated that the obtained films could retard protein degradation, microorganism growth, and lipid oxidation, extending the shelf-life by 9 days at 4 °C. These findings suggest that Zein-GA@CD-MOF films has promising application prospects in pork preservation packaging.

Self‐Powered Luminescent Solar Concentrators‐Integrated Temperature Detection System with High Thermal Tolerance by Reversible Thermal Photoluminescence Luminophores

AbstractIt is still a challenge to prepare the red‐emissive perovskite‐polymer composite with high photoluminescence quantum yield (PLQY) and reversible thermal photoluminescence (RTPL), which is key for improving the thermal tolerance of luminescent solar concentrators (LSCs). In this work, the red‐emissive (661 nm) CsPb(Br0.25I0.75)3‐PMMA composite with high PLQY of 85.96% and favorable RTPL below 160 °C is reported via a strategy of the defect passivation by halide ligand additives. The composite film possesses excellent long‐term stability in air, water, and high temperature environments. Then, a self‐powered temperature detection system, which consists of LSCs and a temperature detection module based on the RTPL composite film, is fabricated. On one hand, RTPL composite makes LSCs of superior thermal tolerance even after 100 cycles of temperature between room temperature and 160 °C. On the other hand, RTPL composite in the opaque box of the temperature detection module can give rise to the signal light without the interference of ambient light. As a result, the self‐powered temperature detection system achieves the quantitative temperature data display at different environment lights for 24 h in a day.

Effect of Cr on the microstructure and corrosion behavior of nickel-based alloys in hydrochloric acid

Nickel-base alloy is a type of metal material with excellent properties and is widely used in many fields. However, in the harsh environment of the acid solution, corrosion causes the reduction of the service life of the alloys, thereby limiting the alloys' use and development. In this paper, the effect of Chromium (Cr) content on the microstructure and corrosion behavior of nickel-based alloys in hydrochloric acid (HCl) was studied by scanning electron microscopy (SEM), energy dispersive spectrum (EDS), electron backscatter diffraction (EBSD) and electrochemical workstation. Meanwhile, X-ray photoelectron spectroscopy (XPS) was used to investigate the composition and properties of the surface passive films. For the Cr20 and Cr30 alloys with a single face-centered cubic (FCC) structure, the Cr2O3 content in the passive films increased with the Cr content, effectively improving the corrosion resistance. As the Cr content continued to increase, the second phases having a body-centered cubic (BCC) lattice were precipitated both in the Cr40 and Cr50 samples, inducing microgalvanic corrosion, thus deteriorating the corrosion resistance. XPS results showed that, in the Cr30 alloy, the relative content of Cr2O3 and the bound water were the highest, indicating that its passive film had the best corrosion resistance. For the passive film, the pitting resistance was related to Cr content, appropriate Cr content improved the corrosion resistance.

Bio-inspired Mechanically Responsive Smart Windows for Visible and Near-Infrared Multiwavelength Spectral Modulation.

Mechanochromic light control technology that can dynamically regulate solar irradiation is recognized as one of the leading candidates for energy-saving windows. However, the lack of spectrally selective modulation ability still hinders its application for different scenarios or individual needs. Here, inspired by the generation of structure color and color change of living organisms, a simple layer-by-layer assembly approach toward large-area fabricating mechanically responsive film for visible and near-infrared multiwavelength spectral modulation smart windows is reported here. The assembled SiO2 nanoparticlesand W18O49 nanowires enable the film with an optical modulation rate of up to 42.4% at the wavelength of 550nm and 18.4% for the near-infrared region, separately, and the typical composite film under 50% stretching shows ≈41.6% modulation rate at the wavelength of 550nm with NIR modulation rate less than 2.7%. More importantly, the introduction of the multilayer assembly structure not only optimizes the film's optical modulation but also enables the film with high stability during 100000 stretching cycles. A cooling effect of 21.3 and 6.9 °C for the blackbody and air inside a model house in the real environmental application is achieved. This approach provides theoretical and technical support for the new mechanochromic energy-saving windows.

STRUCTURES OF HDPE/GaAs AND HDPE/GaAs<Te> COMPOSITES IRRADIATED WITH GAMMA QUANTA

The results of optical studies of structural changes in composite HDPE/GaAs and HDPE/GaAs<Te> films irradiated with gamma quanta at doses of 100, 200, and 300 kGy at room temperature are presented. It was found that gamma irradiation of the initial polymer and their composite films leads to the formation of optical absorption bands at 220 and 280 nm, indicating the formation of C = 0 and C = C-bonds. It was established that composite HDPE/GaAs<Te> films are the most radiation-resistant in the absorbed dose range of 100…300 kGy.

Waterproof strain sensor based on silver/graphene composite film for fine and large strain detection

The development of waterproof sensors with fine and large strain detection capabilities can be better applied to the monitoring of human physiological signals, such as fine physiological signals and joint activities with large amplitude. In this paper, we studied a waterproof sensor by using microstructures to improve the sensitivity of the sensor, and using graphene to bridge microcracks in the silver film, which makes the sensor has low detection limit (as low as 0.2 % strain) and large strain stability detection(up to 50 % strain) with high sensitivity (GF=1814.25, 44 %<ε < 50 %), excellent durability (1,400 dynamic responses), and water resistance(48 h). This makes it suitable for fine and large strain detection, including arterial pulse signals, vibration, and large movements of joint flexion.

Flexible composite films with ultrahigh through-plane thermal conductivity yet low graphene content

Graphene-based polymeric composites have become one of the promising thermal interface materials (TIMs) for the high integration electronic devices due to the excellent intrinsic thermal conductivity of graphene. However, the challenges still remain, such as ordered alignment of graphene in elastic polymer and regulation of phonon scattering at graphene/graphene interface. In this study, a vertically oriented graphene framework within a flexible silicone rubber matrix was fabricated by non-solvent induced phase separation (NIPs) coupled with an in in-situ welding technique. The as-prepared film exhibits an outstanding through-plane thermal conductivity of 29.5W/mK at low graphene loading of 7.5 wt%, which indicates an exceptionally high thermal conductivity enhancement per 1 wt% graphene content (specific TCE) over 1950 %/wt%. Furthermore, the composite films demonstrate excellent conformability inherited from the silicone rubber matrix and achieves low contact resistance of 40–70 Kmm2W−1 under various pressure and interfacial conditions. This study contributes to a deeper insight into the development of the high-performance graphene-based polymeric TIMs.

Constructing multi-dimensional alternating layer nested structure for enhancing electromagnetic shielding, thermal management and strain sensing

It is imperatively desired to design excellent electromagnetic interference (EMI) shielding and thermal management simultaneously. Herein, fabricating the multi-dimensional alternating layer nested (MALN) structure composite film, which consisted of the alternating multilayer structure constructed by silver nanowires (AgNWs)/cellulose nanofiber (CNF) layer and the graphene nanoplates (GNPs)/CNF layer, the dense conducting networks built by interweaving AgNWs in CNF networks, and the “mille-feuille” structure of GNPs and CNF. The heterogeneous layers of AgNWs/CNF layer and GNPs/CNF layer with significant conductivity differences, as well as the “mille-feuille” structure of CNF and GNPs, provide abundant macro/micro heterogeneous interface polarization losses and multiple reflection losses. Adjusting the addition of AgNWs or GNPs in different layers to form the conductivity gradient, endowing the “absorption-reflection–absorption” loss path and excellent conduction loss of film. Therefore, the MALN structure composite film with a thickness of 90 μm exhibits an impressive EMI shielding efficiency (SE) of 98.95 dB and a specific SE (SSE/t) of 11606.14 dB/g·cm−2, attribute to its excellent conduction loss, abundant macroscopic/microcosmic heterogeneous interfacial polarization losses, multiple reflection losses, and the absorption-reflection–absorption loss path. Meanwhile, the in-plane thermal conductivity (λ∥) and out-plane thermal conductivity (λ⊥) achieve of 8.69 W/(m·k) and 0.16 W/(m·k). Additionally, the obtained film also demonstrates exceptional joule heating, remarkable photothermal conversion, outstanding mechanical properties, and distinguished strain sensing capabilities, which exhibiting significant potential in wearable electronic devices.

Regulating the microstructure and hydrophilicity of cellulose nanofibers using taurine and the application in humidity sensor and actuator

Exploring the interrelationships between microstructure, hydrophilicity, humidity response, and material stability through molecular structure design and low-cost preparation, and manufacturing sensing and driving materials with a perfect balance between structures and properties is crucial for biomimetic robots and intelligent devices. Herein, inspired by the capillary phenomenon, the cellulose nanofiber (CNF) was grafted by using taurine to form the “micro cilia” microstructure on its surface (CNF-TAU). By controlling the cilia density and symmetry, the hydrophilicity of the materials was adjusted, and the water was allowed to quickly separate from the inside of the materials, which led to improving the humidity sensitivity and stability of materials. Concretely, compared with CNF, the puncture load, tearing strength, and elongation at break of the CNF-TAU-1.0 were improved by 11.95 times, 2.16 times, and 15.6 %, respectively, and excellent tensile strength was presented. Moreover, the hydrophilicity of CNF-TAU was first weakened and then enhanced with TAU content increasing. At last, the CNF-TAU-1.0 (WCA 55.43°) was selected and blended with single-layer graphene oxide (GO) to prepare CNF-TAU/GO composite films by vacuum filtration. The results indicated that the composite film had excellent mechanical (room and high humidity), humidity responsiveness, and humidity gradient-driven properties. In detail, the CNF-TAU/GO-10 % composite film had the generated stable induced voltage (68.4 mV), the fast response/recovery time (0.3 s/0.9 s), the large max. bending angle (178.4°), and the drive cycle stability (1000 cycles). Moreover, the composite film could be applied to produce biomimetic soft robots, such as human fingers and butterfly-shaped robots.

Copper nanoclusters combined with polymer films as highly sensitive colorimetric probes for visual and proportional fluorescence detection of hexavalent chromium ions in pH and natural waters

In this study, a novel type of fluorescent nanocomposite film was prepared, which could be used for pH value sensing and detecting heavy metal hexavalent chromium ions. Copper nanoclusters doped into polyvinyl alcohol polyethylene glycol fluorescent nanocomposite film (CuNCs/PVA/PEG) has excellent fluorescent properties; it can not only be used as a pH sensor but also can selectively detect heavy metal hexavalent chromium ions. When pH>9, the CuNCs/PVA/PEG composite film will be quenched, which can be used as pH sensing. In addition, the CuNCs/PVA/PEG composite film can detect heavy metal hexavalent chromium ions with a detection line of 0.01 μM. It shows that the probe can detect Cr6+ quickly, sensitively, and selectively and has broad application prospects in environmental analysis applications.

Lignin and green solvent extracted phenolic compounds from date palm leaves as functional ingredients for the formulation of soy protein isolate biocomposite packaging materials: A circular packaging concept

The current study investigated valorization of lignin nanoparticles (LNPs) and phenolic compounds loaded in chitosan (DLECNPs) extracted from date palm leaves into the soy protein isolate (SPI) biocomposite films. The mechanical, structural, barrier, physiochemical, thermal, optical, antioxidant, and antimicrobial properties of the formulated composite films were investigated. The findings showed that the incorporation of DLECNPs into the SPI films significantly improved the film's antioxidant properties by more than 3 times and showed antibacterial inhibition zone in the range of 10–15 mm against six pathogenic bacteria. Further, incorporating LNPs into SPI-DLECNPs films notably improved the mechanical properties from 4.32 MPa and 29.27 % tensile strength and elongation at break, respectively to 10.13 MPa and 54.94 %, the water vapor permeability from 7.38 g/Pa s m to 5.59 g/Pa s m, and the antibacterial inhibition zone from a range of 10.2 mm to 15.0–21.5 mm as well as making the films more heterogeneous and stronger than control SPI film. Moreover, LNPs changed the initial films' color from light yellow to dark red and reduced the films' transparency. The results indicated that LNPs reinforced SPI composite films showed significant improvements in several properties and thus can be used as a potential ingredient for formulation of biodegradable packaging films.

The influence of anodization on laser transmission welding between high borosilicate glass and TC4 titanium alloy

This study investigates the influence of the thickness of the oxide film formed on the surface of TC4 titanium alloy after anodization on the laser transmission welding between the titanium alloy and high borosilicate glass. The effects of oxidation time on the morphology and thickness of the oxide film were examined, and the elemental and phase composition of the oxide film were characterized. The differences in welding strength, weld morphology, and fracture surface between the titanium alloy before and after oxidation treatment and high borosilicate glass welding were compared, and analyzed the welding seam formation mechanism. Within our research scope, the results indicate that with an increase in oxide film thickness, the surface roughness gradually increases and the internal voids gradually increase, resulting in a decrease trend in the bonding strength of the welded joints with the increase in oxide film thickness. The interpenetrating structure formed by the mutual infiltration of glass and metal in the molten pool is identified as the main reason for their connection.

Biomass carbon nanosphere-based piezoresistive flexible pressure sensors for motion capture and health monitoring

Biomass carbon-based flexible sensors have shown significant potential in various applications. Indeed, biomass carbon-based flexible sensors, such as carbonized cotton fabrics, exhibit limitations in terms of sensitivity and response speed. Herein, a kind of biomass carbon nanosphere-based flexible pressure sensor was proposed and developed by embedding biomass carbon nanospheres on the skin-hair structures of the polydimethylsiloxane surface. The carbon nanospheres were obtained through the carbonization of cuttlefish ink. Owing to the skin-hair structures fabricated on the surface of the composite films, the sensors achieve a sensitivity of 135.2 kPa−1 in the pressure range of 0–1 kPa. In addition, the sensors exhibit a short response (43 ms) and recovery time (23 ms). With these properties, the sensors can capture and monitor various motions as well as the characteristic waveforms of the wrist pulse, such as the percussion wave (P wave), tidal wave (T wave), and diastolic wave (D wave).

Electron beam pretreatment of carboxymethyl nanofibrillar cellulose reinforced polyvinyl alcohol-based degradable composite membranes: Preparation, characterization and property optimization

This study investigated the development of biodegradable composite films blending carboxymethyl-modified peanut hull nanocelluloses (CMNCs) pretreated by electron beam irradiation with polyvinyl alcohol (PVA). The films were characterized by their structure, physicochemical properties, and degradation characteristics. The carboxyl group of CMNCs and the hydroxyl group of PVA enhance the network structure of the film through hydrogen bonding. This is most notably manifested in the fact that when CMNCs with a substitution degree of 0.38 and an addition amount of 4 % were added, the CMNCs were uniformly dispersed in the PVA matrix with a flat and smooth surface of the plastic and a dense structure. Meanwhile, the water contact angle (57.14°), the tensile strength (47.28 N/mm2) and elongation at break (156 %) of the composite films were significantly increased, and the water content (12.71 %) was decreased. The hydrophobic and mechanical properties of the composite plastics were improved considerably. In addition, the addition of 4 % CMNCs with a degree of substitution of 0.66 and a high dose of electron beam irradiation (120 KGy) to PVA made the degradation rate of the composite plastic in the first week (31 %) much higher than that of pure PVA (3 %). At the same time, the light transmittance of the composite plastic decreased significantly in both visible and UV ranges. EBI pretreatment significantly improved the degradation and light barrier properties of the composite plastics. Therefore, this study may provide new ideas for EBI pretreatment-assisted chemical modification of nanocellulose to prepare functional composite films.

Enhancement of the hygrothermal ageing properties of gelatine films by ethylene glycol diglycidyl ether

Owing to the instability of gelatine in hygrothermal environments, gelatine-based cultural heritage undergo various deterioration processes, such as cracking, peeling, warping, curling and fracture, posing significant threats to its long-term preservation. Building on previous research, this study investigates the stability of polyol glycidyl ether–gelatine composite films under high-humidity and high-temperature conditions using ethylene glycol diglycidyl ether (EGDE) as a model compound. The hygrothermal ageing properties of EGDE–gelatine composite films are evaluated in terms of macrosize, mesoscopic structure, surface properties and mechanical properties. Results indicate that EGDE enhances the dimensional stability and swelling ratios of the composite films, stabilizes the pore structure and distribution and maintains the hydrophilicity and molecular structural stability under hygrothermal ageing conditions. Furthermore, the incorporation of EGDE leads to superior stress–strain properties of the composite films in such challenging environments. This study provides valuable experimental data for the preparation and conservation applications of gelatine-based cultural heritage materials.

Effects of chitin nano-flake fillers on the mechanical and barrier properties of polylactic acid biocomposite films

Polylactic acid (PLA) is a biodegradable polymer extensively used in packaging; however, its mechanical and barrier properties require enhancement for wider applications. Chitin-derived nanoflakes (CNFL), a two-dimensionally separated nanomaterial derived from α-chitin, possess high strength and toughness, making them ideal additives for improved PLA performance. This study investigated the effect of CNFL on the properties of PLA composite films. Incorporating CNFL significantly enhanced the mechanical properties of PLA, increasing its tensile strength and stiffness while preserving flexibility. This enhancement was attributed to the nucleating effect of CNFL, which increases crystallinity. Additionally, CNFL improved the thermal stability of the composite films by mitigating thermal deformation. Notably, the oxygen barrier properties of CNFL-filled PLA composites were also enhanced, demonstrating a significant reduction in oxygen permeability at optimal CNFL concentrations due to increased tortuosity of the oxygen diffusion path. Overall, CNFL-filled PLA composites exhibit great potential as renewable packaging materials, particularly for protecting sensitive products, such as food and pharmaceuticals, from oxidative degradation, thereby extending shelf life and maintaining quality. These findings suggest that CNFL-filled PLA composites are promising materials for advanced applications, offering a combination of enhanced mechanical performance, improved thermal stability, and superior oxygen barrier properties.