Multilayer Composite Films Research Articles

Dye-sensitized solar cells achieved with multi-layered SnO2/ZnO composite photoanodes through precise control of thickness and composition

The spin coating is cost-effective, straightforward, and highly suitable for the large-scale production of solar cells. In this study, we report the fabrication of SnO2/ZnO composite films for dye-sensitized solar cells (DSCs) using a simplified and cost-effective spin-coating technique on fluorine-doped tin oxide glass substrates. This study introduces a new way of preparing a multi-layered composite thin film using a suspension containing colloidal SnO2 nanoparticles and ZnO nanoparticles followed by sonication and aging of TiO2-free high-efficiency DSCs. Our approach provides a facile way of obtaining a uniform film of tunable thickness with high reproducibility by adjusting the total number of coating cycles. The spin-coating process achieved a nano-sized SnO2-covered ZnO layer, contributing to enhanced conversion efficiency in DSCs. A specific number of seven coating cycles was identified as optimal for achieving the aspirational performance. Under standard AM 1.5 irradiation with an intensity of 100 mW/ cm2, the fabricated SnO2/ZnO composite films revealed an overall energy conversion efficiency of 6.5% with a thickness of 2.06 µm which is impressive for a TiO2-free DSC. This achievement indicates the potential of the developed fabrication process for cost-effective and scalable production of efficient DSCs with SnO2/ZnO composite.

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.

Spin-coating ANF based multilayer symmetric composite films for enhanced electromagnetic interference shielding and thermal management

The demand for flexible composite films with electromagnetic interference (EMI) shielding capabilities is rapidly increasing. Balancing high EMI performance with flexibility and portability has become a critical research focus in practical applications. In this study, an optimized strategy for aramid nanofibers (ANF) films was developed using spin-coating and sol–gel techniques. The resulting film features a smooth surface and excellent mechanical properties. ANF, initially an insulator, was transformed into a conductor through the in-situ polymerization of ion-doped polypyrrole (PPy). Leveraging a multilayer structural strategy, we prepared a symmetric composite film, ANF@PPy-(TA-MXene)-AgNWs-(TA-MXene)-ANF@PPy (PMA), using vacuum-assisted filtration and lamination hot pressing. This film, composed of ANF@PPy (PA) as the matrix, tannic acid (TA) modified MXene, and silver nanowires (AgNWs) as fillers, exhibited multiple shielding mechanisms as electromagnetic wave (EMW) passed through its various layers. This multilayer configuration provides significant flexibility in EMW shielding. Moreover, TA-modified MXene expands the lamellar spacing, enhancing the scattering efficiency of EMWs within the film, and serves as a medium connecting the upper and lower layers. This results in the efficient integration of the multilayer structure, synergistically improving both EMI shielding performance and mechanical properties. When the ratio of PA/MXene/AgNWs was 1:3:1, the film demonstrated optimal properties, including an EMI shielding effectiveness of 70.2 dB, thermal conductivity of 4.62 W/(m•K), and tensile strength of 50.2 MPa. Due to the exceptional EMI shielding and thermal properties of the PMA composite film, it holds great potential for applications in artificial intelligence, wearable heaters, and military equipment.

Ultra-Low Loading Fillers Induced Excellent Capacitive Performance in Polymer-Based Multilayer Nanocomposites under Harsh Environments.

Multilayer-structured nanocomposites are recognized as a prominent strategy for overcoming the paradox between the breakdown strength (Eb) and polarization (P) to achieve superior energy storage performance. However, current multilayer-structured nanocomposites involving substantial quantities of nanofillers (>10vol.%) for high dielectric constant as polarization layer will inevitably deteriorate mechanical properties and breakdown strength. Herein, an innovative approach is reported to breaking conventional rules by designing a multilayered polymer composite with ultralow loading of Al2O3 nanoparticles, i.e., 0.3vol.% for polarization layers and 2vol.% for insulation layers. By modulating the spatial distribution of Al2O3 nanoparticles in polymer, a significantly increased interfacial dipole response is induced, and deep interfacial traps are constructed to capture the mobile charges, thereby suppressing high-temperature conduction loss. The resulting multilayered polymer composite exhibits an unparalleled discharged energy density of 7.8 Jcm-3 with a charging/discharging efficiency exceeding 90% at 150°C. This work provides valuable insights into achieving superior capacitive performance in multilayer composite films operating under extreme conditions.

Development of multilayer composite film based on protein‐polysaccharides with the addition of onion waste extracts and their impact on the shallot quality

AbstractAt present, multilayer composite film is attractive in the production of biodegradable films due to its essential film properties. The current study mainly focused on overcoming the problems of poor water barrier and mechanical strength observed in monolayer films (SA‐CMC and G/SA‐CMC) made from gluten (G), sodium alginate (SA), and carboxymethylcellulose (CMC). The film was developed with the addition of onion waste extracts (OWEs), primarily from peel and stalk, to enhance functional properties. The multilayer composite film consists of three layers: an outer layer made of G, an inner layer made of SA, CMC, and a middle layer made of G/SA‐CMC. The developed composite film exhibited improved physical properties (thickness: 0.348–0.629 mm and moisture: 20.889%–21.403%), mechanical properties (tensile strength: 21.943–20.640 MPa), and barrier properties (WVP: 0.212–0.516 g/m.s.Pa × 10−14) compared to monolayer films (SA‐CMC and G/SA‐CMC). The addition of OWEs enhanced the multilayer film's phenolic (20.076 and 36.175 mgGAE/g) and antioxidant activity (73.850% and 42.667%). The study found that the multilayer control film had minimal changes in weight loss (9.75% ± 0.18%) and firmness (6.68 ± 0.64 N) compared to OWEs‐added films (9.93% ± 0.49–10.02% ± 0.14% and 6.61 ± 0.37 to 6.64 ± 0.18 N). However, fresh‐peeled shallot onion packed with control film exhibited higher bacterial counts (6.70 ± 0.42 CFU/g) and yeast and mold counts (5.08 ± 0.20 CFU/g) than those packed with the OWEs‐added film (6.49 ± 0.28–6.56 ± 0.27 CFU/g and 4.75 ± 0.18–4.89 ± 0.21 CFU/g), indicating that OWEs protect the onions from microbial degradation. Overall, the multilayer control film (without OWEs) showed better results for storing the fresh‐peeled shallot onion at 4°C for 21 days.Highlights Onion waste extracts have potent high antioxidant and antimicrobial properties Multilayer film's physical, mechanical, barrier, and functional properties improved Addition of onion waste extracts increased the film's antimicrobial activity Control film showed a better effect for storing fresh‐peeled shallot onion Developed film can store fresh‐peeled shallot onion for 21 days at 4°C.

Significantly enhanced energy storage performance in multi-layer polyimide films with nano dielectric layer

Polymer-based composites with multilayer structure were emerging as an effective way to solve the contradiction between high breakdown strength and large permittivity in past decades. However, the incorporating layers in conventional multilayer composite films are usually inorganic thick films, which is not beneficial for the retention of excellent mechanical properties of the polymer matrix. In this work, the multilayer films consisting of micrometer polyimide (PI) and nanoscale TiO2 layer were prepared by spin-coating and atomic layer deposition (ALD), respectively. Carrier migration in PI-TiO2 multilayer films was hindered effectively by the interfacial barrier, as indicated by the results of the Pulsed Electro-Acoustic (PEA) tests. Compared to pure PI, both the permittivity, dielectric loss and breakdown strength were optimized in the PI-TiO2 multilayer films. A satisfactory discharge energy density of 6.77 J cm−3 (efficiency >90 %) was obtained in the multilayer films, which is about 5 times higher than that of pure PI. The strategy of constructing heterogeneous interfaces by incorporated nanoscale TiO2 layers is promising for designing high performance capacitors in practical application.

High-Temperature Multilayer Composite Films of Polyethylene/Ethylene Vinyl Alcohol with Enhanced Flexural Moduli and Gas Barrier Properties

High-Temperature Multilayer Composite Films of Polyethylene/Ethylene Vinyl Alcohol with Enhanced Flexural Moduli and Gas Barrier Properties

Scalable multilayered dielectric polymer film exhibiting significantly improved high-temperature energy density

Dielectric polymers, serving as crucial dielectric media in high-power-density energy storage devices, play a pivotal part in modern industries and electrical systems. However, the rapid degradation of breakdown strength and charge-discharge efficiency in elevated temperature environment imposes formidable limitations on the utilization of polymer dielectric under extreme conditions. Here, a series of polyetherimide/polysulfone alternating multilayer composite films are prepared using a non-equilibrium processing method, which effectively blocks the development of breakdown paths by the interface barriers in the multilayer structure. The deep trap sites within the interface capture the charge carriers excited at high temperatures, thus decreasing conduction loss and enhancing the efficiency and breakdown field strength of the dielectric polymer. Consequently, excellent capacitive performances including a high energy density of 5.4 J cm−3 with an efficiency exceeding 90% at 200 °C and cycle stability up to 106 cycles have been obtained. Furthermore, the multilayer polymer capacitors (MLPC) constructed from composite films also exhibit significant flexibility and thermal stability. This work provides valuable insights for the advancement of high-temperature energy storage polymers with commercial application value.

Application of multi-layered composite fiber films with enhanced piezoelectric performance in flexible energy harvesting devices

Flexible electronic components such as wearable sensors, energy harvesting devices, and human health monitoring systems based on piezoelectric materials have garnered significant attention within the scientific community. In this study, PZT nanofibers were modified with dopamine hydrochloride prior to their integration into PVDF fibers, serving as piezoelectric reinforcements to enhance the mechanical and piezoelectric characteristics of composite fiber films. Subsequently, a facile hot-pressing method was employed to fabricate multilayered films characterized by a densely packed surface fiber arrangement and a loosely organized internal fiber orientation, which markedly improved the self-supporting ability and fiber density of the electrospun fiber films. A detailed investigation into the micro-morphology, crystallinity, and enhanced piezoelectric properties of the films was conducted. Notably, the composite fiber film containing 6 wt% PZT NFs exhibited a peak piezoelectric coefficient (d33) of 29 pC/N, resulting in an output voltage of 13.8 V. This represents a 2.23-fold enhancement in d33 value and a 4.6-fold increase in output voltage when compared to the pristine PVDF fiber film, which had a d33 of 13 pC/N and an output voltage of 3 V. The power density achieved by the sensor is 0.73 μW/cm2. This performance is underpinned by a high piezoelectric coefficient, outstanding output characteristics, and robust stability, which collectively enhance the sensor's efficacy in various applications. This research presents an effective approach for augmenting the piezoelectric performance of PVDF-based composite films and paves the way for the advancement of piezoelectric energy harvesting applications.

Anti-Oxidized Self-Assembly of Multilayered F-Mene/MXene/TPU Composite with Improved Environmental Stability and Pressure Sensing Performances.

MXenes, as emerging 2D sensing materials for next-generation electronics, have attracted tremendous attention owing to their extraordinary electrical conductivity, mechanical strength, and flexibility. However, challenges remain due to the weak stability in the oxygen environment and nonnegligible aggregation of layered MXenes, which severely affect the durability and sensing performances of the corresponding MXene-based pressure sensors, respectively. Here, in this work, we propose an easy-to-fabricate self-assembly strategy to prepare multilayered MXene composite films, where the first layer MXene is hydrogen-bond self-assembled on the electrospun thermoplastic urethane (TPU) fibers surface and the anti-oxidized functionalized-MXene (f-MXene) is subsequently adhered on the MXene layer by spontaneous electrostatic attraction. Remarkably, the f-MXene surface is functionalized with silanization reagents to form a hydrophobic protective layer, thus preventing the oxidation of the MXene-based pressure sensor during service. Simultaneously, the electrostatic self-assembled MXene and f-MXene successfully avoid the invalid stacking of MXene, leading to an improved pressure sensitivity. Moreover, the adopted electrospinning method can facilitate cyclic self-assembly and the formation of a hierarchical micro-nano porous structure of the multilayered f-MXene/MXene/TPU (M-fM2T) composite. The gradient pores can generate changes in the conductive pathways within a wide loading range, broadening the pressure detection range of the as-proposed multilayered f-MXene/MXene/TPU piezoresistive sensor (M-fM2TPS). Experimentally, these novel features endow our M-fM2TPS with an outstanding maximum sensitivity of 40.31 kPa-1 and an extensive sensing range of up to 120 kPa. Additionally, our M-fM2TPS exhibits excellent anti-oxidized properties for environmental stability and mechanical reliability for long-term use, which shows only ~0.8% fractional resistance changes after being placed in a natural environment for over 30 days and provides a reproducible loading-unloading pressure measurement for more than 1000 cycles. As a proof of concept, the M-fM2TPS is deployed to monitor human movements and radial artery pulse. Our anti-oxidized self-assembly strategy of multilayered MXene is expected to guide the future investigation of MXene-based advanced sensors with commercial values.

Space charge measurements for multilayer heterogeneous composite films by thermal pulse method

Multilayer composite films are suitable for high-temperature and high-electric-field insulation, but the accumulation of space charge may lead to the degradation of their insulating properties. However, few studies have been reported on space charge distribution in multilayer composite thin films due to the limitations of space charge measurement techniques. In this study, using Al2O3/PI and BOPP/PI composite structural samples as numerical examples, we proposed a method for calibrating electric fields in multilayer heterogeneous structures and combined it with the Tikhonov regularization algorithm, and successfully reconstructed the electric field distribution inside the samples. Based on this, the experimental results show that the reconstruction of the overall electric field in the BOPP/PI composite samples is consistent with the combined electric field reconstructed after the individual measurements of each layer, which further confirms the feasibility and validity of the use of thermal pulse to measure the charge distribution in multilayer heterogeneous composite films.

Characterization of multilayer bacterial cellulose-chitosan films loaded with grape bagasse antioxidant extract: Insights into spectral and water properties, microstructure, and antioxidant activity

This work explores the development and characterization of composite multilayer films comprising bacterial cellulose (BC) and chitosan enriched with antioxidant compounds from grape bagasse extract (GE) and glycerol. SEM images revealed a compact structure with successful interactions between BC and chitosan, confirmed by FT-IR analysis. Equilibrium moisture content, water vapor permeability (WVP), swollen capacity, and solubility were systematically investigated, unveiling the influence of glycerol and GE concentrations. Moisture content increased with elevated glycerol and GE levels, attributed to their hydrophilic nature. WVP rose with higher concentrations of hydrophilic compounds, affecting the films' permeability. Swollen capacity decreased, and solubility increased with the addition of GE and glycerol, indicating a more compact film structure. The incorporation of GE conferred antioxidant properties to the films, as evidenced by DPPH and ABTS+ assays, and Total Phenolic Content (TPC) determination. TPC values varied from 0 to 1.75 mg GAE/g dried film, depending on GE. Fourier Transform Infrared Spectroscopy (FT-IR) highlighted polymeric associations, and UV–Vis spectra demonstrated enhanced UV-blocking properties. Overall, these multilayer films offer promising applications in food packaging, leveraging natural antioxidant sources for an enhanced functionality.

The application of C/Sb composite multilayer films on fast flexible phase change memory

In this paper, the phase transformation properties of C/Sb composite multilayer films based on flexible substrates were studied. After different times of bending, the flexible films can still achieve amorphous to crystalline phase transition, but the crystalline resistance increases to different degrees. When the bending times are less than 15000 times, the deformation makes the grain fine, the surface of the film tends to be flat, the surface electric field effect is weakened, and the resistance drift is reduced. When the bending times are higher than 15000 times, cracks begin to appear in the film, and the cracks’ depth and width increase with the bending times. The distribution of C and Sb elements at the crack was analyzed by scanning electronic microscope energy spectrum. The phase change memory device of C/Sb composite multilayer film based on flexible PEEK substrate has been made, and the rapid reversible resistance transition (∼10 ns) in various complex states has been successfully achieved. This research provides a new idea for flexible information storage.

Big-small size design of carbon-based multilayer films for improved wear life

Anti-wear is an essential prerequisite for the reliability and durability of silicon-based micro/nano devices operation. To design lubricating films suitable for micro/nano devices, big-small size carbon composite multilayer films were introduced to improve wear life, which is called grain size refining effect of multilayer films. Specifically, graphene oxide (GO) nanosheets and carbon quantum dots (CQDs) were alternately spin-coated to create (GO/CQDs)n multilayer films as solid lubricant. The results show that (GO/CQDs)5 multilayer film exhibits superior wear resistance with the wear life of 9400 s under a high load of 4 N. The service life of (GO/CQDs)5 film is more than six times than that of (GO)5 film. The excellent friction performance of (GO/CQDs)5 multilayer is attributed to the layered 3D structure composed of GO nanosheets alternate with CQDs, in which the rigid GO nanosheets act the role in load-carrying capacity, and CQDs could be helpful to enhance deformation resistance of film. Meanwhile, friction-induced structural transformation makes part GO convert into graphene on sliding interface, which is benefit for reducing friction. It is expected that such multilayers will be good lubricating films for silicon-based micro/nano devices.

Multifunctional syndiotacticity-rich poly (vinyl alcohol)/MXene sediment for multilayered composite films with effective electromagnetic interference shielding and thermal conductivity

Utilizing remarkable polymer matrix and efficient filler to propose an ingenious strategy for designing composite films synergistically with high electromagnetic interference shielding effectiveness (EMI SE) and thermal conductivity. Herein, a novel type of flexible composite film based on syndiotacticity-rich poly (vinyl alcohol) (sPVA)/modified MXene sediment (mMS) is fabricated through an alternating casting approach. The sPVA/mMS multilayered film containing effective noncovalent combining between sPVA layer and mMS layer not only presents a high strength of ∼66.3 MPa but also possesses a superior electrical conductivity of 683 S/m. Notably, the mMS layer with dense conductive and thermal networks endows the 95-μm-thick composite film with the synergy of favorable EMI SE (∼15.8 dB) in the X band and impressive in-plane thermal conductivity (3.31 W/mK, enhanced by ∼2365%). Moreover, this multilayered architecture realizes multiple internal reflection-absorption of microwaves and efficient heat dissipation, while confers the film with advantageable flame retardancy and significant water resistance. Therefore, sPVA-based composite films from MS provide a promising solution for the development of multifunctional polymeric materials tailored for upcoming electronic devices in challenging environments.

Hydration and mechanical properties of arabinoxylan, (1,3;1,4)-β-glucan, and cellulose multilayer films simulating the cell wall of wheat endosperm

The cell walls of wheat endosperm, which play a pivotal role in seed germination, exhibit a laminated structure primarily composed of polysaccharides. In this study, composite multilayer films were prepared using arabinoxylan (AX), (1,3;1,4)-β-D-glucan (MLG), and cellulose nanofibers (CNFs), and the effect of polymer blend structure on cell wall hydration and mechanical properties was investigated. Atomic force microscopy and X-ray diffraction indicated that the network structure of MLG/CNF exhibits a higher degree of continuity and uniformity compared to that of AX/CNF. Mechanically, the extensive linkages between MLG and CNFs chains enhance the mechanical properties of the films. Moreover, water diffusion experiments and TD-NMR analysis revealed that water molecules diffuse faster in the network structure formed by AX. We propose a structural model of the endosperm cell wall, in which the CNFs polymer blend coated with MLG serves as the framework, and the AX network fills the gaps between them, providing diffusion channels for water molecules.

Sequential reinforcement of intra/interlayer interfaces to design flexible, transparent electromagnetic interference shielding film for “Green Electronics”

A sequential reinforcement strategy is used to prepare multilayer composite films by enhancing intra/interlayer interactions via physical and chemical bonds. The films show flexibility, transparency, EMI shielding, gas barrier, and fire retardancy.

Multinanolayered PA6/Cloisite and PE/PA6/Cloisite composites: Structure, mechanical and barrier properties

Economic and environmental challenges are driving development towards more efficient and lighter materials. Polyethylene (PE) and polyamide (PA6) are among the most used polymers and their assembly in multilayer make them efficient protective materials. The aim of this work is to design new multilayer composite films based on polyethylene and polyamide with high barrier properties. A coextrusion process with layer multiplier elements (LME) made it possible to carry out 100 μm-thick multilayer films containing 5 up to 1025 layers. Loaded PE/PA6 multilayer films were made by incorporating Cloisite particles (organo-modified montmorillonite – C30B) at 5 wt% into the PA6 layers. For comparison PA6 films with and without fillers were also made by using the same coextrusion process. The structural and thermal properties of all multilayer films were correlated with the water and gas barrier properties. A good dispersion of exfoliated C30B in the PA6 phase was observed even for the thinnest confined layers of PA6 in PE/PA6 multilayers (∼90 nm). We showed the complexity of the multinanolayer structures involving interphases as well as the complexity of the transfer mechanisms. The serial model used for predicting permeability highlighted some significant improvements of the gas barrier properties of confined PA6 layers. The barrier effect on all the multilayer films was, however, limited due to the “on-edge” orientation of the crystalline phases and structural defects induced during the coextrusion process. Despite this, the confinement of nanofillers in PA6 multilayers and in PA6 layers of PE/PA6 multilayers allowed to increase the barrier properties of multilayers.

Multilayer BOPET dielectric film with internal double electron barrier for high temperature applications

With the continuous development of modern electronic and power equipment, practical applications in harsher environment call for film capacitors with higher temperature resistance. Here, we designed a multilayer film including two outer layers of biaxially oriented polyethylene terephthalate (BOPET), two inorganic layers of boron nitride nanosheets (BNNSs), and an intermediate epoxy layer. Due to the blocking effect of the BNNSs layer, the propagation of the breakdown path is hindered, which improves the breakdown strength of the film. Meanwhile, the carrier transport in the medium is effectively hindered, reducing the conduction loss of the composite film. As a result, the optimized multilayer composite film had a high discharged energy density of 8.76 J/cm3, maintaining a high charge-discharge efficiency of 95% at 25 °C, while remarkable values of 7.04 J/cm3 and 73% were obtained even at 150 °C, which showed prominent improvements compared with BOPET. Thus, it turns out to be a promising strategy of fabricating high temperature dielectric films.

Structure design and properties of MXene-WPU-Co/C electromagnetic shielding composite films

Excess electromagnetic radiation generated during the operation of electronic equipment does not only interfere with the normal operation of precision electronic instruments, but also endangers the human health. Most of the available electromagnetic shielding materials function via reflection mechanism, which can lead to serious secondary electromagnetic waves pollution. Herein, MXene-WPU-Co/C multilayer composite films with controllable thickness and reflectivity have been prepared using Co/C magnetic particles mixed with environmentally friendly waterborne polyurethane (WPU) as the electromagnetic wave absorbing layer and MXene (Ti3C2Tx) as the conductive layer. Remarkably, an electromagnetic shielding efficiency of 31 dB was achieved in the X-band with a reflectivity (R) of 0.01 and enhanced absorption capacity (SEA/SET =99%) when the thickness of the MXene-WPU-Co/C-10 film was 0.2 mm and the mass fraction of MXene was only 10%. Compared with similar electromagnetic shielding materials, this novel low-cost and controllable design strategy affords extremely excellent performances, high efficiencies, and low reflections of electromagnetic shielding films.