Composite Films Research Articles

A flexible porous polyimide/copper composite film toward high-mass-loading anodes in lithium-ion batteries

Conventional metal foil current collectors are essential for electronic conduction in lithium-ion batteries, but the planar structure limits the fast transporting of electron and the power density. Herein, a light, conductive, self-extinguishing, and flexible porous polyimide/copper composite film (PIF/Cu) derived from a polyimide foam was fabricated via hot pressing and electroless plating methods. The honeycomb structure was illustrated in PIF/Cu under a 3D X-ray tomography microscope, revealing the successful construction of a 3D conductive network. PIF/Cu-30 possessed an electronic conductivity of as high as 3.6 × 105 S m−1 at a bulk density of 0.26 g cm−3 and exhibited exceptional structural stability even after successive and harsh mechanical loads. Graphite with a mass load of 12 mg cm−2 was loaded into the PIF/Cu-30 to prepare the anode for cell assembly. The cells using PIF/Cu-30 achieved a better performance in capacity retention (98.2 %@60 cycles) than those using traditional Cu foils (55.1 %@60 cycles), which resulted from the fast transport of electrons and Li-ion through the 3D conductive networks in the porous PIF/Cu-30.

Flexible multifunctional composite films for adjustable EMI shielding behavior under self-fixed deformation

With the widespread application of electromagnetic technology, the significance of intelligent electronic devices in modern communication is increasingly prominent. Despite this, the public focuses more on the harm caused by electromagnetic pollution. However, traditional EMI shielding materials struggle to meet the diverse and dynamic application requirements. Hence, developing materials capable of adjusting EMI shielding has become imperative to satisfy various scenarios. This paper presents the composite film TAPU-MXene, which is capable of adjustable EMI SE under self-fixed deformation. Introducing tannic acid increases the innermolecular interactions of TAPU. This enhancement leads to remarkable improvements in mechanical performance, achieving a stress level of 36.6 MPa at a strain of 560 %. Furthermore, the catechol groups can establish non-covalent interactions with multiple substrates, endowing the TAPU film with remarkable adhesion and self-healing capabilities. By combining the highly conductive nano-filler MXene with TAPU, the EMI shielding composite film TAPU-MXene is obtained. The EMI SE of TAPU-MXene was up to 56.7 dB when MXene loading was 3 mg cm−2. Most importantly, TAPU-MXene exhibits the ability to adjust the EMI shielding effectiveness from 56.7 dB to 2.75 dB under self-fixing deformation through shape memory mechanism, demonstrating promising applications in the field of adjustable EMI shielding materials.

Synthesis of Carboxylate-Dialdehyde Cellulose to Use as a Component in Composite Thin Films for an Antibacterial Material in Wound Dressing

Synthesis of Carboxylate-Dialdehyde Cellulose to Use as a Component in Composite Thin Films for an Antibacterial Material in Wound Dressing

Flexible Piezoelectric Nanocolumnar Composite Films as Flat-Panel Loudspeakers: Application and Modeling.

Highly anisotropic piezoelectric composites promise to progress electroacoustic devices as a class by combining the advantages of both piezoceramics and polymers. Fundamentally, piezoelectric loudspeakers employ the converse piezoelectric effect to convert electrical to mechanical energy. Quasi-1-3 piezoceramic/polymer composites enable flat-panel loudspeakers that are tunable in elastic modulus, with opportunities for mechanical flexibility, optical transparency, and large-area coverage. Their processing route enables relatively flexible design parameters, such as the particle loading, polymer-matrix modulus, film thickness, film size, and electrode-material stiffness. Alternative processing routes of electric field (E-field) aligned-piezoelectric composites are demonstrated, including using the relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) to enhance the acoustic performance and photocurable resins to accelerate the materials processing. Material properties critical for dielectrophoresis are characterized, and loudspeakers were fabricated based on the optimal processing conditions. Subsequently, electroacoustic characterization explores the effect of loudspeaker size, substrate stiffness, the microphone distance, the piezoceramic material, and the matrix modulus. Finally, finite-element (FE) modeling of the electromechanical behavior validates the natural frequencies and modes shapes of the loudspeakers via the analytical solution and frequency response to electrical and mechanical excitation. Good correspondence between the predicted electroacoustic performance and experimentally validated model is observed.

High-sensitivity fiber temperature sensor based on composite film structure and lossy mode resonance

In this work, we proposed and demonstrated a high-sensitivity optical fiber temperature sensor based on lossy mode resonance (LMR). The sensor is composed of a D-shaped fiber and a thin composite film. The composite film consists of tin dioxide (SnO2) and polydimethylsiloxane (PDMS). PDMS is inserted as an intermediate layer between D-shaped fiber and SnO2 layer, realizing the separation of TM and TE polarization to reduce polarization crosstalk, while also serving as a temperature sensitive layer. The polarization state of the excited LMR can be freely controlled by adjusting the thickness of the composite film. The proposed sensor exhibits a high temperature sensitivity of −1.1883 nm/°C with a measurement range of 10–90 °C. Meanwhile, a fast response time of ∼ 109 ms was observed due to the ultra-thin PDMS interlayer.

The effect of NaY‐zeolite on mechanical, thermal, and spectroscopic behavior of crosslinked polyvinyl alcohol films

AbstractThe effects of sodium y zeolite (NaY‐zeolite) on crosslinked Polyvinyl alcohol (CrPVA) composite films were investigated. The spectroscopic analysis showed that crosslinks were formed between PVA, Tartaric acid (TA), and NaY‐zeolite particles. The thermal stability of the CrPVA film was improved with the addition of zeolite. Optimum thermal stability was observed for 5 wt % zeolite content. It can be seen that the mechanical properties also improved for 5 wt % zeolite‐doped CrPVA composite films when compared with CrPVA. It was observed that Young's modulus increased 54.14 to 74.49 MPa. While the degree of crystallinity of the composite film decreased from 20.42 to 14.77% due to zeolite content. This is thought to be due to the increase in the structure's crosslinking rate. The utilization of TA and NaY zeolite in membrane applications may be considered an advantage for improving the mechanical characteristics and the recyclability of membrane technology.

Enhanced Energy Storage Properties of Four-Layer Composite Films via Strategic Macrointerface Modulation.

Dielectric capacitors play a crucial role in the field of energy storage; however, the low discharged energy density (Ue) of existing commercial dielectrics limits their future applications. Currently, further improvement in the Ue of dielectrics is constrained by the challenge of simultaneously achieving high permittivity (εr) and high breakdown electric field strength (Eb). To address this issue, we designed a series of four-layer poly(vinylidene fluoride) (PVDF)-based composite films comprising three functional layers: a sodium bismuth titanate (NBT) plus PVDF composite (NBT&PVDF) layer to achieve high εr values and a pure PVDF layer and a boron nitride (BN) plus PVDF composite (BN&PVDF) layer to achieve high Eb values. This design synergistically enhanced the εr and Eb values of the composite films by exploiting low-loss macrointerface polarization via adjustment of the functional layer stacking order, as supported by simulation analyses. Ultimately, the composite film with a topmost layer of pure PVDF, followed by an NBT&PVDF layer, another pure PVDF layer, and a BN&PVDF layer achieved an enhanced Ue value of 26.42 J·cm-3 and excellent efficiency of 80.03% at an ultrahigh Eb value of 770 MV·m-1. This approach offers an innovative pathway for developing advanced energy storage composite dielectrics via macrointerface manipulation.

Effect of thiourea concentration on the structural, optical and photoelectric properties of ZnO/ZnS/PVC composite films used as flexible UV photodetectors

Effect of thiourea concentration on the structural, optical and photoelectric properties of ZnO/ZnS/PVC composite films used as flexible UV photodetectors

A Comprehensive Review about Risks of Type-II Diabetes on Ocular Tear Film

Millions of people worldwide suffer from diabetes mellitus (DM), which can lead to systemic issues in a number of organs. Ocular problems, such as dry eye syndrome (DES), are among its less well-known side effects. This review delves into the interactions between diabetes and the composition of tear films, emphasizing alterations in the mucin, aqueous and lipid layer. Dry eye symptoms are exacerbated by induced changes in the components of the tear film in diabetes DM, which lead in decrement in tear production, increment in tear evaporation and tear film instability. Lipid layer is a lubricant, that reduces friction between the ocular surface and the eyelids which promotes high-quality, smooth refractive surface. The lacrimal function unit shields the tear film, preserves the normal function of the ocular surface. The mucin layer is secreted by the conjunctival goblet cells, in hyperglycemia the functionality of the cells are reduced thus, the mucin secretion is also altered which causes instability of the tear film. Diabetic patients can have their tear film integrity assessed with the help of diagnostic methods like Schirmer's Test and Tear Break- Up Time (TBUT). In order to relieve symptoms and maintain ocular health, there should be a complete management of diabetes and the induced tear film disorders.

Catalytically Active Gold Nanoparticles on Star Block Co-polymer Matrix: Synthesis of Nanocomposite Film Exploring the Langmuir-Blodgett Technique.

Nanocomposites with metal nanoparticles and block copolymers distributed in a stable and robust thin film are preferred for various applications. Here, synthesis of such a nanocomposite is reported, which is composed of gold nanoparticles (AuNPs) embedded in a tetronic 701 (T701) and 90R4 (T90R4) thin film matrix generated using the Langmuir-Blodgett (LB) thin film technique. Tetronics contain a monoprotonated central ethylenediamine group at pH 5 due to the presence of chloroauric acid (HAuCl4) in the subphase, along with poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) blocks, both of which have the capacity to serve as the reducing agent toward chloroaurate anion (AuCl4-). Calorimetric experiments have shown that T90R4 has a better interaction with AuCl4-, probably due to its better electrostatic interaction with AuCl4- ions due to the higher % of the hydrophilic PEO group. On the other hand, the T701-AuNP interaction turned out to be more spontaneous due to the higher hydrophobicity of T701 (higher PPO/PEO ratio). The optical properties and structure/morphology of these nanocomposites are characterized by UV-vis spectroscopy, FTIR spectroscopy, XRD, and TEM. The composite thin film has the ability to catalyze the organic electron transfer process between p-nitrophenol and p-aminophenol in the presence of sodium borohydride. A clear correlation has been found between the reaction rates and the kind of tetronic present in the nanocomposite, which acted as a matrix and stabilizer toward AuNPs.

Analysis of composite wavelength multilayer dielectric film damage based on the field-thermal effect

Taking SiO2/HfO2 multilayer dielectric films as the research object, when the total laser energy is the same, the effects of different laser parameters on film damage under 1064 nm and 355 nm composite wavelength pulse irradiation are analyzed. The results show that different energy ratios lead to exponential differences in the electron number density inside the film, but they are far from reaching the field damage threshold. Comprehensive analysis shows that film damage is mainly affected by thermal melt and stress. The greater the difference between an energy ratio of 1ω and 3ω, the greater the thermal stress in the film, the higher the stress peak, and the more obvious the damage effect of thermal stress on the film. Under the condition of 50%1ω, the thermal effect in the film is minimal, which can ensure that the film is not damaged as much as possible. The model method used in this paper only takes the current film system as an example for specific research and can be extended to all film systems for analysis.

Preparation and Characterization of Tensile Properties of PMMA/SiC Nanowhiskers Nanocomposite Films: Effect of Filler Loading and Silane Treatment

The preparation of nanocomposites through melt mixing was challenging as the nanofillers tend to form agglomeration. The silicon carbide nanowhiskers (SiCNWs) filled poly (methyl methacrylate) (PMMA) thin film in this study was prepared by means of solution casting. Acetone with low toxicity was used as solvent to dissolve the PMMA pellets. A coupling agent, silane was used to enhance the properties of composite films. Besides, the untreated and treated SiCNWs were filled into PMMA matrix, respectively with the filler loading varied from 0.2 to 0.8 wt%. The universal testing machine was used to investigate the tensile properties of composites. It was found out that the tensile strength of the PMMA was reduced in the presence of SiCNWs. However, the tensile strength had increased with the rise of filler loading. At 0.8 wt% of SiCNWs, the composites’ tensile strength was comparable to virgin PMMA. Meanwhile, the SiCNWs had reduced the elongation at break but increased the elastic modulus of PMMA/SiCNWs nanocomposite films. In addition, silane surface treatment on SiCNWs had improved the tensile strength and ductility but lowered the elastic modulus of the nanocomposites. The improvement was due to the enhancement of interfacial adhesion between SiCNWs and PMMA.

Flexible Composites with Rare-Earth Element Doped Polycrystalline Particles for Piezoelectric Nanogenerators

Energy harvesting plays an important role in advancing personalized wearables by enabling continuous monitoring, enhancing wearable functionality and facilitating sustainable solutions. We aimed to develop a flexible piezoelectric energy harvesting system based on inorganic piezoelectric materials that convert mechanical energy into electricity to power a wide range of mobile and portable electronic devices. There is significant interest in flexible piezoelectric energy harvesting systems that use inorganic piezoelectric materials due to their exceptional physical features and prospective applications. Herein, we successfully demonstrated a flexible piezoelectric nanogenerator (PENG) designed by the co-doped rare-earth element ceramics (RE-PMN-PT) embedded in PVDF and PDMS composite film and attained a significant output performance while avoiding electrical poling process. The impact of dielectric characteristics on the electrical output of nanogenerators was investigated, together with the structure of the composites. The Sm/La-PMN-PT particles effectively amplify both the voltage and current output, showcasing their potential to power portable and wearable devices, as demonstrated by their capacity to illuminate LEDs. The maximal output power of 2 mW was correlated with the high voltage (220 V) and current (90 µA) of Sm/La-PMN-PT/PVDF, which demonstrated that the device has the potential for energy harvesting in biomedical applications.

Effect of Morphology and Concentration of CeO2 Nanoceria on the Thermal Stability of Polyvinyl Alcohol Films

Objective: To determine the thermal stability of polyvinyl alcohol films under different concentrations of CeO2 nanoceria. Method: Cerium Oxide doped polyvinyl alcohol (PVA) nano-composites were synthesized by the traditional solution casting method for various concentrations of nano CeO2 by solution combustion method. The thermal properties of prepared PVA-2.5 wt% CeO2, PVA-7.5 wt% CeO2 , PVA-12.5 wt% CeO2, and PVA-25 wt% CeO2 composite films were elucidated by using techniques such as Differential Scanning Calorimetry, Thermogravimetry analysis and Differential Thermal analysis. Findings: The glass transition temperature of the pure PVA is found to be 114°C, whereas it varies between 110°C-120°C for composite films. The melting temperature of the composite films is the same as that of pure PVA except in the case of 7.5wt% CeO2 and 25wt% CeO2 composites. The reduced melting point of these composites elicits a decrease in crystallinity. A 12.5 wt % and 25 wt% CeO2-PVA nano-composite films exhibit an increase in the final degradation temperature, a high specific heat capacity, low mass loss, and a larger residual weight, indicating their potential applicability in thermal coating and thermal sensing applications. Polyvinyl alcohol (PVA) films are being used routinely as a dielectric layer for electrical applications due to the good physiochemical and dialectic properties of the material. An incorporation of CeO2 nanoceria improves not only the thermal but also the mechanical properties of PVA and extends its application for electrical and optical operation. Here in the present study, different concentrations of CeO2 were incorporated with the PVA and analysed for the thermal properties. The study showed that 12.5 wt % and 25 wt% CeO2-PVA nano-composite enhanced PVA film thermal stability. Keywords: PVA-CeO2 Nanocomposites; Differential Scanning Calorimetry; Thermogravimetry Analysis and Differential Thermal Analysis; Physical properties and thermal properties

CsPbBr3 and Cs2AgBiBr6 Composite Thick Films with Potential Photodetector Applications

This paper investigates the optoelectronic properties of CsPbBr3, a lead-based perovskite, and Cs2AgBiBr6, a lead-free double perovskite, in composite thick films synthesized using mechanochemical and hot press methods, with poly(butyl methacrylate) as the matrix. Comprehensive characterization was conducted, including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–visible spectroscopy (UV–Vis), and photoluminescence (PL). Results indicate that the polymer matrix does not significantly impact the crystalline structure of the perovskites but has a direct impact on the grain size and surface area, enhancing the interfacial charge transfer of the composites. Optical characterization indicates minimal changes in bandgap energies across all different phases, with CsPbBr3 exhibiting higher photocurrent than Cs2AgBiBr6. This is attributed to the CsPbBr3 superior charge carrier mobility. Both composites showed photoconductive behavior, with Cs2AgBiBr6 also demonstrating higher-energy (X-ray) photon detection. These findings highlight the potential of both materials for advanced photodetector applications, with Cs2AgBiBr6 offering an environmentally Pb-free alternative.

Construction of Vertically Interconnected Microdiamond Channels Inspired by Subcutis for Thermal Conductivity Enhancement of Polymer Composite Films

Construction of Vertically Interconnected Microdiamond Channels Inspired by Subcutis for Thermal Conductivity Enhancement of Polymer Composite Films

Chlorophyll Films for Radiation Dosimetry: A Feasibility Study

Abstract Novel Chlorophyll-PVA composite films have been prepared and tested for the dosimetry of therapeutic radiation. The radiation response has been quantified using UV-Vis spectroscopy. FTIR and XRD spectroscopies have been used to characterize the physical properties and irradiation response of the films. The films have shown response towards the therapeutic x-rays beams of 6 MV nominal energy in the tested dose range of 0.25 Gy to 32 Gy in discrete dose levels occurring in the geometric progression series of 2. The dosimeter has been found to exhibit sensitivity at a low dose of 0.25 Gy. The dose response curve of the dosimeter exhibits an exponential relationship of the absorbance and absorbed dose. A region of saturated absorbance has been observed beyond 4 Gy. The peak intensities of the FTIR spectra have been found to decrease with increasing doses as compared to the unirradiated samples, because of the changes in the bond polarities and molecular geometries. The XRD spectra indicates a change in the molecular orientation resulting in a decrease in peak intensity with increasing dose. This study indicates the feasibility of chl-PVA films in the dosimetry of therapeutic radiation. This film dosimeter can be processed locally with minimum resources and standardized against a known standard before clinical use. The chlorophyll molecules need careful handling owing to their sensitivity to light and temperature.

Composite film based on carboxymethyl cellulose and gellan gum with honokiol-β-cyclodextrin inclusion complex: Characterization and application in strawberry preservation

The aim of this study is to fabricate a biodegradable film based on carboxymethyl cellulose and gellan gum (CMC/GG) with the honokiol/β-cyclodextrin inclusion complex (HNK/β-CD). The HNK/β-CD was prepared by freeze-drying and its physicochemical properties were investigated. Then HNK/β-CD was added to CMC/GG solution to form CMC/GG honokiol inclusion complex (HIC) composite film by the casting method. The physicochemical properties, antioxidant and antibacterial effects, and strawberry preservation function were investigated. The composite film with 0.18 % inclusion complex (CMC/GG/0.18 % HIC) was found to be the optimal formulation. The film had a tensile strength of 8.20 MPa and an elongation at break of 115.17 % with water vapor permeability of 0.48 g·mm·(cm2·h·KPa)−1. The increase of HNK/β-CD content yielded lower optical transmittance and water content of CMC/GG/HIC composite film, while improved the hydrophilicity value. The 2,2-diphenyl-1-picrylhydrazyl radical and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) scavenging capacities of CMC/GG/0.18 % HIC composite film were 80.83 % and 53.10 % respectively. CMC/GG/HIC composite film was bacteriostatic against Staphylococcus aureus and Candida albicans but not against Escherichia coli and Aspergillus niger. Packing strawberries with the optimized composite film can retain the appearance, titratable acidity and vitamin C content of strawberries, which was better than the commercially fresh-keeping film control group. The CMC/GG/HIC composite film overcame the shortcomings of a single material, and gained importance in food packaging applications.

Mechanically strong, transparent polyimide composite thin films with a low dielectric constant

Aromatic polyimide is widely used in microelectronics as dielectric packaging layers. There is a high demand to reduce its dielectric constant to meet the fast development of communication technology. Here we report a simple and eco-friendly approach to preparing polyimide films with a lowered dielectric constant by adding silica hollow nanospheres with an average size of 100 nm in an aqueous solution of poly(amic acid) salt, and subsequent film casting and thermal imidization. The silica hollow nanospheres present a uniform distribution in polyimide matrix after surface modification with 3-aminopropyltriethoxysilane. The dielectric constant of the resulting composite films decreases linearly with particle loading till 15 wt% and reaches the lowest value of 2.5. The surface hardness and elastic modulus of the films improve by adding hollow nanospheres, while maintaining high optical transparency, high flexibility and a low coefficient of thermal expansion.

Synthesis and EMI shielding study of Ni (II) semicarbazone driven nickel nanoparticles

Herein, we report the synthesis of nickel nanoparticles (Ni-NPs) from Ni (II) complexes of cyclic semicarbazone derivatives and their electromagnetic interference (EMI) shielding behaviour. Ni (II) complexes of cyclic semicarbazones were synthesized and characterized by various spectroscopic tools. It was observed that such complexes are excellent precursors for the synthesis of Ni-NPs when reduced by hydrazine hydrate. It is expected that the reaction kinetics will be ably normalized by the presence of semicarbazone ligand and that upon dissociation and partial consumption during nano-particle formation, will provide an added advantage of mild functionality around the particles. Overall various nickel complexes obtained from cyclic semicarbazones were tested as an effective precursor for the synthesis of Ni-NPs which were characterized by XRD, TEM, SEM, and AFM, and their magnetic behaviour was studied by VSM. EMI shielding efficiency of flexible Ni/PVA composite films showed shielding efficiency of about minus (−) 30 dB in X-band (8–12 GHz) for about 25 % loading in the PVA matrix.