Composite Films Research Articles

Modified Chitosan-Based Coating/Packaging Composites with Enhanced Antibacterial, Antioxidant, and UV-Resistant Properties for Fresh Food Preservation.

Chitosan-based biomass packaging materials are a promising material for food preservation, but their limited solubility, antioxidant capacity, UV resistance, and mechanical properties severely restrict their application. In this study, we developed a novel chitosan-based coating/packaging composite (QCTO) using quaternary ammonium salt and tannic acid (TA)-modified chitosan (QCS-TA) and oxidized chitosan (OCS). The introduction of quaternary ammonium salt and TA effectively improves the water solubility and antibacterial, antioxidant, and UV-resistant properties of chitosan. The Schiff-base bond formed between OCS and QCS-TA, along with the TA-mediated multiple interactions, conferred the prepared composite film with good mechanical properties (69.9 MPa tensile strength) and gas barrier performance to water (14.3 g·h-1·m-2) and oxygen (3.5 g·mm·m-2·h-1). Meanwhile, the prepared QCTO composites demonstrate excellent biocompatibility and safety and are applied as coatings for strawberries and bananas as well as packaging films for mushrooms. These preservation experiments demonstrated that the prepared composites are able to effectively reduce weight loss, prevent microbial growth, maintain color, and significantly prolong the shelf life of fresh products (bananas, strawberries, and mushrooms extended shelf life by 6, 5, and 6 days, respectively). Therefore, the developed QCTO coating/packaging film shows great potential for applications in the field of food preservation and packaging.

EFFECT OF CHEMICAL MODIFICATION OF MULTIWALL CARBON NANOTUBES ON THE PROPERTIES OF POLY(LACTIC ACID) COMPOSITE FILMS: SYNTHESIS AND CHARACTERIZATION

To enhance the properties of poly(lactic acid) (PLA) composite films, unmodified (MWCNT) and modified multiwall carbon nanotubes (MWCNT-COOH, MWCNT-OH, and MA-g-MWCNT) were incorporated into the polymer matrix followed by the solvent casting method. The success of the modification of MWCNT with maleic anhydride (MA) was verified by absorption transmission reflectance spectroscopy (ATR). The fabricated nanocomposite films were analyzed by Fourier transform infrared (FT-IR) spectroscopy, thermal analyses, atomic force microscopy (AFM), contact angle measurements, dynamic mechanical analysis (DMA), and electrical conductivity tests. ATR spectra showed that MA was covalently grafted to the surface of the MWCNT, which was well dispersed and homogenously incorporated in the PLA matrix. The results of the thermal degradation demonstrated that the degradation value of the film increased from 328.91oC to 347oC with the addition of 0.5 wt% MA-g-MWCNT. Additionally, the MWCNT-OH/PLA films illustrated strongly hydrophilic nature due to the –OH groups. The surface resistance of 3 wt% of the MWCNT-COOH/PLA nanocomposite film decreased from 2.56x109 to 2.42x103 Ω (by 106 order). Therefore, the properties of PLA were increased with the addition of functionalized MWCNTs, which can be used for different applications such as biomedical, food packaging, and electronics.

Development of a cellulose nanofiber composite film containing CuO/ZnO nanoparticles and its human norovirus inactivation properties in clams

Human norovirus (HuNoV) threatens human health worldwide, highlighting the critical need for antiviral materials. In this study, copper and zinc nanoparticles (NPs) as inorganic antiviral materials and a cellulose nanofiber (CNF) were selected to construct a hybrid inorganic-organic composite film (CuO/ZnO NPs-CNF) against MS2 and murine norovirus 1 (MNV-1) (surrogates for HuNoV) viruses. Selected NPs concentrations (50µM of CuO NPs and 5mM of ZnO NPs) showed non-toxicity (89.88% of cell viability) through the MTT assay. Upon the development and characterization of the CuO/ZnO NPs-CNF film, high compatibility between CuO/ZnO NPs and CNF was identified, along with consistent thickness, low moisture content, and water solubility. A synergistic antiviral effect was exhibited in vitro and on the film against MS2 and MNV-1 in the mentioned co-treated inorganic matrix within 1h. The antiviral stability of the film was also maintained at various temperatures (-18°C, 5°C, and 25°C) and humidities (20–30%, 50–60%, and 70–80%). When a synergistic antiviral effect was exhibited on the CuO/ZnO NPs-CNF film against both MS2 and MNV-1, mechanisms analysis by SDS-PAGE and RT-qPCR revealed that there were damages to both capsid protein and RdRP. The application of CuO/ZnO NPs-CNF film on clams resulted in a significant decrease in the survival rate of MS2 by up to 65.67% and MNV-1 by up to 78.62% when treated at low temperatures compared to the CNF film. Taken together, these results suggest that the CuO/ZnO NPs-CNF film could be used as potential anti-HuNoV agent in the food industry.

High-rate Deposition of Crystalline TiHfN Ultra-thin Films by Closed-field Dual-cathode DC Unbalanced Reactive Magnetron Sputtering without External Substrate Heating

High deposition rate titanium hafnium nitride (TiHfN) ultra-thin film deposition was successfully prepared by closed-field dual-cathode DC unbalanced reactive magnetron sputtering. All prepared films were polycrystalline. The morphology and atomic composition of the TiHfN ultra-thin film were characterized by field-emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The columnar structure could be promoted by increasing the deposition time. Lastly, the surface-enhanced Raman scattering (SERS) activity was investigated by Rhodamine 6G (R6G) drop-dried TiHfN ultra-thin film surface. The TiHfN ultra-thin films deposited at 20 s were found to have a high SERS activity, whose detection of R6G molecule at 10-5 M. The result could open preliminary studies on ternary transition metal nitride (TTMN) thin films for the alternative plasmonic sensors as SERS chips.

Green-synthesized antibacterial and unidirectional water-permeable polylactic acid/ZnO composite film for enhanced preservation of perishable fruits

Green-synthesized antibacterial and unidirectional water-permeable polylactic acid/ZnO composite film for enhanced preservation of perishable fruits

UV Detectors Based on In₂O₃–Ga₂O₃ Composite Films

UV Detectors Based on In₂O₃–Ga₂O₃ Composite Films

Tetraphenylethylene-based conjugated polymers with valine-containing side chains: Aggregation-induced emission, helical self-assembly, complexation-induced circularly polarized luminescence

Realizing high circularly polarized luminescence (CPL) in polymer system is an important but challenging task. Herein, we provide a strategy for designing conjugated polymers with high CPL performance upon the complexation with mandelic acids. Two tetraphenylethylene (TPE)-based conjugated polymers, l-P1 and d-P1, were synthesized by Sonogashira polycoupling reactions between the TPE-containing diethynyl monomer and dibromo aryl monomers carrying valine methyl ester groups. Both the polymers showed aggregation-induced emission (AIE) properties and the capabilities to self-assemble into regular helical nanostructures on nanoscale and fluorescent microfibers on microscale. They exhibited weak circular dichroism (CD) signals; upon the complexation with R/S-mandelic acids, their CD absorption and fluorescence emission can be efficiently enhanced. The composite films of l/d-P1 and R/S-mandelic acids exhibited excellent complexation-induced CPL properties with the absolute luminescence dissymmetric factor (glum) up to 0.01 and the fluorescence quantum yield up to 26.8%; the glum values showed little dependence on their emission wavelength. Various types of carboxyl acids have been screened and only mandelic acids show significantly chiroptical induction. The specific interaction between mandelic acids and l/d-P1 also makes the latter promising candidates for the enantioselective recognition of chiral organic molecules.

Unveiling the emerging trends of egg components-based biodegradable food packaging development: A comprehensive review.

Food packaging plays a crucial role in the food supply chain by aiding in food preservation and reducing food losses throughout the distribution process. The extensive, unregulated utilization, and waste mismanagement of food packaging materials made up of conventional petroleum-based plastics has led to a significant environmental crisis. Egg components-based food packaging has attracted considerable attention from the global packaging industry as a viable alternative to synthetic polymers due to its biodegradability, sustainability, and health-related benefits. This comprehensive review explores the composition and properties of egg components (eggshell, eggshell membrane, egg white, and egg yolk), and recent advancements in biodegradable packaging films derived from them. Additionally, it introduces the characteristics of these films and their applications in food, highlighting their biodegradability, sustainability, and suitable mechanical, barrier, thermal, optical, antioxidant, and antimicrobial properties as substitutes for traditional synthetic polymers. The utilization of various egg components in the packaging industry is a safe, non-toxic, cost-effective, and economical approach. However, it was found that incorporating active compounds from natural sources into packaging films, as well as composite films composed of egg components combined with other biopolymers, resulted in superior properties, compared to single component films. Moreover, the application of novel technologies in film development has proven to be more effective than conventional methods. These innovative egg components-based packaging films can be optimized and commercialized for use as packaging materials for food products.

Photodimerization-Triggered Photopolymerization of Triene Coordination Polymers Enables Macroscopic Photomechanical Movements.

Controlling the packing of olefinic molecules in crystals is essential for triggering solid-state [2 + 2] photocycloaddition reactions and the synthesis of photocontrolled smart materials. Herein, we report the stepwise photodimerization-triggered photopolymerization of two triene coordination polymers (CPs), {[Zn(2-BBA)2(tpeb)]·0.5CH3CN}n (1, 2-HBBA = 2-bromobenzoic acid, tpeb = 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene) and {[Zn(3-BBA)2(tpeb)]·CH3CN)}n (2, 3-HBBA = 3-bromobenzoic acid). Upon irradiation with 420 nm light, each pair of closely packed and parallel olefinic bonds in 1 undergoes a [2 + 2] cycloaddition reaction, which connects two adjacent Z-shaped chains into a ladder-like coordination chain [Zn(2-BBA)2(bpbdpvpcb)0.5]n (1a, bpbdpvpcb = 1,3-bis(4-pyridyl)-2,4-bis(3,5-di(2-(4-pyridyl)vinyl)phenyl]cyclobutene) through single-crystal to single-crystal (SCSC) transformation. After photodimerization from 1 to 1a has occurred, the olefinic bonds that were initially distant are brought in close enough proximity to meet the requirements for a subsequent [2 + 2] cycloaddition reaction. Upon further light irradiation, the neighboring bpbdpvpcb ligands in 1a experience a SCSC photopolymerization based on [2 + 2] photocycloaddition and transform into poly-3b,4,5,5a,8b,9,10a-octahydro-4,5,9,10-tetrapyridyl-2,7-di(2-(4-pyridyl)vinyl)dicyclobuta[e,l]-pyren (poly-otpdpvdcbp). 2 showed similar structural changes under UV light illumination. Under light exposure, single crystals of 1 and 2 with different morphologies exhibit bending, cracking, and jumping photomechanical motions. The composite film (1-PVA) engineered by dispersing crystalline particles of 1 in poly(vinyl alcohol) (PVA) displays interesting light-wavelength-dependent photomechanical motions and can perform photodriven swimming on a liquid surface. This work provides a useful and promising approach to enable photodimerization of those photoinactive olefin pairs embedded in CPs and opens a new route to synthesize organic polymers by using olefinic CP platforms.

Dynamic borate ester bond reinforced hydroxyethyl cellulose/corn starch crosslinked film for simple recycling and regeneration.

Endowing biodegradable plastics with easy recyclability can reduce competition with food resources and further enhance their environmental friendliness. In this work, 4-carboxyphenylboronic acid was grafted onto the side chains of hydroxyethyl cellulose and compounded with inexpensive cornstarch. Upon the introduction of tannic acid, stable and reversible borate ester bond rapidly formed, yielding composite biodegradable plastic films with outstanding mechanical properties and facile recyclability. The formation of a dynamic cross-linked network mitigates the aggregation of gelatinized starch molecules, enhancing the flexibility and durability of the crosslinked film. Testing revealed that while maintaining high tensile strength, the elongation at break of the crosslinked film increased by 952.86 %. The static water contact angle was improved from 32.74° to 78.82°, with a change of <5° within 1 min, demonstrating enhanced water resistance. Excellent antioxidant and thermal stability were also characterized, the crosslinked film can be easily dissolved by heating in water at pH = 6.5 and reshaped in water at pH = 7.2. After five times of regeneration, the tensile strength loss was as low as 5.68 %. This eco-friendly and efficient recycling process is promising during green chemistry.

Preparation of polymer dispersed liquid crystal doped with bilayer nanofiber membranes and phase‐change microcapsule coating for enhanced infrared modulation

AbstractThe effective manipulation and regulation of infrared (IR) radiation represent significant advancements in the realm of liquid crystal applications. In this investigation, the synergistic integration of nanofiber membranes and phase change microencapsulated film with polymer dispersed liquid crystal (PDLC) layers was employed for IR modulation. To obtain the excellent electro‐optical properties of PDLC composite films, the ratio of the PDLC system, the thickness of the nanofiber membrane, and the concentration of phase‐change microcapsules were meticulously regulated, and the polymer network morphology of the PDLC films was analyzed to achieve a high contrast ratio (162.72) of PDLC composite films. The fabricated PDLC composite devices show excellent IR shielding efficiency of 15% in the presence of doped nanofiber membranes and phase change microencapsulated films. Notably, patterned nanofiber layers and phase‐change microcapsule coating were obtained by template electrospinning, resulting in patternable PDLC composite film devices.

Development of sunflower protein isolate emulsion‐based edible composite films with the addition of potato starch: Barrier, mechanical, thermal, and morphological properties

Development of sunflower protein isolate emulsion‐based edible composite films with the addition of potato starch: Barrier, mechanical, thermal, and morphological properties

Coordination Compound Guided a Novel Composite Film with Zn2V2O7 Nanoflake and VO2@Zn2V2O7 Nanoparticle for Enhanced Thermochromism Smart Window.

Thermochromic vanadium dioxide (VO2) can intelligently modulate the transmittance of indoor solar radiation to reduce the energy consumption of air conditioning in buildings. Nevertheless, it remains a great challenge to simultaneously improve the luminous transmittance (Tlum) and solar modulation ability (ΔTsol) of VO2. In this study, a novel approach is employed utilizing a coordination compound to finely tune the growth of a VO2 based composite film, yielding a hierarchical film comprising Zn2V2O7 nanoflakes and VO2@Zn2V2O7 core-shell nanoparticles. Remarkably, the resulting composite films showcase exceptional optical performance, achieving a Tlum of up to 73.0% and ΔTsol of 15.7%. These outcomes are attributed to the antireflection properties inherent in the nanoflake structure and the localized surface plasmon resonance of well-dispersed VO2 nanoparticles. In addition, the Zn2V2O7-VO2 film demonstrates remarkable environmental durability, retaining 90% of its initial ΔTsol even after undergoing aging at 100°C under 50% relative humidity for a substantial period of 30 days - a durability equivalent to ≈20 years under ambient conditions. This work not only achieves a harmonious balance between Tlum and ΔTsol but also introduces a promising avenue for the design of distinctive composite nanostructures.

Understanding the ion conductivity of self-standing poly-[ethylene oxide] composite films through non fickian diffusion mediated water uptake phenomena

Understanding the ion conductivity of self-standing poly-[ethylene oxide] composite films through non fickian diffusion mediated water uptake phenomena

Ethyl cellulose matrixed poly(sulfur-co-sorbic acid) composite films: Regulation of properties and application for food preservation

Developing non-toxic and sustainable materials with versatile and diverse functions has always been a crucial issue in food preservation packaging. Recently, inverse vulcanization has emerged as a precise and eco-friendly solution, attributed to the versatility of resulting polysulfides. In this study, a polysulfide crosslinked with sorbic acid was prepared by inverse vulcanization, and further combined with bio-macromolecular ethyl cellulose to form composite films via a casting method. Thanks to the ethanol-solubility and good compatibility of ethyl cellulose towards the polysulfide, morphology of the films can be tailored by adjusting the component ratio, thereby achieving favorable water vapor permeability (2.20 × 10−12 gs−1m−1Pa−1), oxygen permeability (4.01 × 10−4 gs−1 m−2), elasticity modulus (~400 MPa), elongation at break (~16 %), etc. Some films demonstrate remarkable antibacterial activity against a broad spectrum of bacteria and fungi, demonstrating their effectiveness in food preservation. The browning and spoilage of preserved Agaricus bisporus were inhibited, with 79.2 % of the initial firmness retained and a 5.6 % weight loss recorded on the 6th day. For the 15-day preservation of grapes, minimal changes in appearance, firmness, or TSS were observed, underscoring the promising potential of this composite for food preservation applications.

Round-the-clock efficient degradation and simultaneous hydrogen evolution over long afterglow light driven Z-scheme Cu|CuO/SrAl2O4:Eu2+,Dy3+ photocatalyst composite film

The dependence of photocatalytic technology on external irradiation light sources limits the round-the-clock utilization of photocatalysts. Meanwhile, CO2 and H2 generated on the photocatalysts are mixed together because traditional photocatalysts are mostly powdery, which requires further separation and purification of the generated gases. In this work, an immobilized Z-scheme Cu|CuO/SrAl2O4:Eu2+,Dy3+ composite film was successfully prepared for the first time as a photocatalyst, enabling round-the-clock degradation of ciprofloxacin and hydrogen evolution on both sides of copper foil. The efficiency of ciprofloxacin degradation and hydrogen evolution was systematically investigated to evaluate the performance of the prepared samples. The results showed that after 180 min of continuous simulated solar irradiation followed by 240 min in darkness, the degradation efficiency reached 84.78 % for ciprofloxacin and 672.29 μmol/g for hydrogen evolution. This work aims to contribute to round-the-clock photocatalytic degradation of organic pollutants and hydrogen evolution.

Low humidity hysteresis and fast response silicon based capacitive humidity sensor based on SiO2 supported GO film

Low humidity hysteresis and fast response are important parameters for evaluating sensor performances. However, it is difficult for a sensor to simultaneously obtain a low humidity hysteresis and fast response time. In this work, a low humidity hysteresis and fast response silicon based capacitive humidity sensor was fabricated based on a two-step deposition strategy using SiO2 and GO. The scanning electron microscope (SEM) was used to characterize the morphologies for the fabricated sensor, demonstrating the successful synthesis of sensitive films. The experimental results suggested that, compared with the pure GO and GO/SiO2 composite film sensors, the two-step deposition strategy fabricated layered SiO2 supported GO film humidity sensor exhibited the lowest humidity hysteresis and the fastest response speed. The humidity hysteresis and response/recovery time are 3.5 % and 3 s/2 s, respectively. The humidity sensing mechanism for the observed low humidity hysteresis and fast response was analyzed via morphologic structures and Young-Laplace equation. This work demonstrates that the morphological structures modulation is an important and effective method for improving sensor performance, providing a valuable reference for high performance sensor fabrication.

A Highly Sensitive D-Shaped PCF-SPR Sensor for Refractive Index and Temperature Detection

A novel highly sensitive D-shaped photonic crystal fiber-based surface plasmon resonance (PCF-SPR) sensor for dual parameters of refractive index and temperature detecting is proposed. A PCF cladding polishing provides a D-shape design with a gold (Au) film coating for refractive index (RI) sensing (Core 1) and a composite film of silver (Ag) and polydimethylsiloxane (PDMS) for temperature sensing (Core 2). Comsol Multiphysics 5.5 is used to design and simulate the proposed sensor by the finite element method (FEM). The proposed sensor numerically provides results with maximum wavelength sensitivities (WSs) of 51,200 and 56,700 nm/RIU for Core 1 and 2 as RI sensing while amplitude sensitivities are −98.9 and −147.6 RIU−1 with spectral resolution of 1.95 × 10−6 and 1.76 × 10−6 RIU, respectively. Notably, wavelength sensitivity of 17.4 nm/°C is obtained between −20 and −10 °C with resolution of 5.74 × 10−3 °C for Core 2 as temperature sensing. This sensor can efficiently work in the analyte and temperature ranges of 1.33–1.43 RI and −20–100 °C. Due to its high sensitivity and wide detection ranges, both in T and RI sensing, it is a promising candidate for a variety of applications, including chemical, medical, and environmental detection.

Preparation and characterization of the Leonardite and Boric acid added Polylactic acid films for food packaging applications

Polylactic acid (PLA), a biodegradable plastic, has begun to replace petroleum-based plastics used in thin film. According to the literature, various clays are used to develop PLA matrix film. In this study, PLA composite films containing specific proportions of Leonardite (LEO) and Boric acid (BOR) were prepared by casting method, and the physical, mechanical, thermal, barrier, and microstructure properties of these films were studied. As the amount of LEO in LEO and BOR/LEO added films increased, correspondingly increased the TS and EM values, while TR and MF values decreased, and the EB values fluctuated. As the amount of BOR increases in BOR added films, the increases and decreases in TS and EM values are similar, while the TR, MF and EB values decrease. In added films, the additive effect is clearly seen in the XRD patterns. While the addition of LEO significantly changed the surface color and opacity, BOR added films showed fewer changes in these properties. The Contact angle measurements demonstrated that, while the addition of BOR reduced the CA value, the addition of LEO partially increased it. The addition of BOR/LEO resulted in an increase in CA value because of the effects of LEO.

Preparation of Coir Cellulose Nanofibers by Peroxyformic Acid Method and Their Application in Reinforced PVA Composite Films

Preparation of Coir Cellulose Nanofibers by Peroxyformic Acid Method and Their Application in Reinforced PVA Composite Films