Polymer Composite Films Research Articles

Effects of polyaniline and silver nanoparticles on the structural characteristics and electrical properties of methylcellulose polymeric films

In this work, novel flexible polymer composite films composed of polyaniline (PANI), silver nanoparticles (Ag-NPs), and methylcellulose are fabricated for portable and wearable electronic devices. The MC/PANI/Ag composite films are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared (FTIR) techniques. The synergistic effects of PANI and Ag-NPs on the electrical conductivity, dielectric permittivity, electric modulus, complex impedance, and the energy density efficiency of MC polymeric film have been determined in the frequency range of 100 Hz to 5 MHz. The XRD and infrared spectroscopy, confirmed the successful fabrication of the MC/PANI/Ag composite films. The SEM images have indicated a homogenous loading and dispersion of Ag-NPs into the MC film. The electrical conductivity has increased from 4.14x10-9 S.cm−1 for pure MC to 1.48x10-6 S.cm−1 for MC/PANI/Ag-NPs. In addition, the dielectric constant ε' has increased from 0.62 for MC to 1.19 for MC/PANI/Ag-NPs at 100 Hz. These results confirmed that there are significant modifications on the fabricated films, which open the road for utilizing the MC/PANI/AgNPs as flexible films for wide range of electronic applications such as batteries, electronic circuit and supercapacitor’s.

The effect of temperature on the electrical and thermal conductivity of graphene‐based polymer composite films

AbstractIn this work, we studied the effect of temperature on the electrical, thermal, and mechanical properties of graphene‐based poly(vinylidene fluoride‐co‐hexafluoropropylene) composites. Graphene‐based polymer composites (PC‐Gn) with various graphene content were prepared using solution mixing and molding process. The physical, chemical, and mechanical properties of the PC‐Gn composites were investigated using different characterization techniques including differential scanning calorimetry, scanning electron microscopy, potentiostatic electrochemical impedance spectroscopy, and dynamic mechanical analysis (DMA). DMA results showed that the strength of obtained PC‐Gn composites increased with higher graphene wt%. The in‐plane electrical and thermal conductivity values were measured over a temperature range from 25 to 125°C using a four‐point probe electrical conductivity system and optothermal Raman technique, respectively. Our results showed that temperature had a noticeable effect on the in‐plane electrical and thermal conductivity values for PC‐Gn where both values gradually decreased by the increment of temperature. We believe that by increasing temperature, the vibration of composite particles became more severe, which increased the system's anharmonicity and strongly reduced the lifetimes of electrons and phonons in the composite. Further analysis, including electrochemical analysis, was also done on all composite films showing that our process produced highly conductive films that potentially can be used in many electrochemical applications in the future.

Efficient Phase-Change Polymer Composite Film from Emulsion Gels Stabilized by Cellulose Nanofiber-Based Amphiphiles

Phase-change polymers (PCPs), exhibiting solid–solid phase transition, bring advancement to the conventional solid–liquid system for thermal energy storage. Such a system obtained as an aqueous dispersion is recommended for application as a surface coating. However, achieving good colloidal stability with efficient energy-storage performance requires precise process designing. Herein, we developed a film-forming PCP that was synthesized from emulsion gels stabilized by cellulose nanofiber-based amphiphiles (CLAm’s). The CLAm was obtained by grafting an amphiphile at a significantly higher degree (0.2–2.4). Depending on the degree of substitution and type of oil, the CLAm was able to efficiently stabilize o/w emulsion gels containing a very high oil phase (>90.0%) at a concentration of about 0.1 wt %. The PCPs were produced by the copolymerization of stearyl methacrylate (SMA) and methyl methacrylate used as the oil phase in emulsion gels. The composite film obtained from the colloidal dispersion of P(SMA-co-MMA) exhibited a solid–solid (crystalline–amorphous) phase transition involving high latent heat of upto ∼98 J/g for the melting and crystallization of SMA segments at ∼35 and ∼25 °C, respectively. This approach provides significant advancement in designing an efficient energy-storage material using plant-derived biocompatible nanomaterials.

Carbon nanodot doped in polymer film: Plasmophore enhancement, catalytic amination and white-light generation

A broader application of carbon nanodot (CD) gets limited due to its feeble emissivity at the red end of the emission spectrum. In this work, we have adopted two-pronged strategies to augment the photoluminescence properties of CD. First, the polymer has been used to avoid aggregation-caused quenching (ACQ). And the further augmentation of the photoluminescence properties of CD by the surface plasmon of silver nanoparticle (Ag-NP). This has been demonstarted by stepwise emission enhancement of emitters present in CD covering the entire visible spectrum. Polymer composite films have been prepared at varying concentrations of Ag-NP for direct observation of metallic nanoparticle-enhanced photoluminescence (MNEP). Such observation has been attributed to the strong bonding interactions of thiol-groups and other functional groups present at the surface of carbon nanodot with the silver nanoparticles. Unprecedentedly, Ag-NP augments nearly 25% of the emission intensity of CD. Interestingly, nanodot is found to exhibit Ag-NP concentration-dependent switching of photoluminescence in composite films and aqueous solutions as well. We show here CD-doped polymer film has the potential to generate white light through LED-down conversion and can effectively catalyze the reductive amination of resazurin and 2,4-dinitrophenol in real-time with relatively high reaction rates.

Experimental investigations on the beta attenuation properties of lead monoxide – Polycarbonate composite films

Lead monoxide filled polycarbonate polymer composite films have been prepared with twelve different filler levels, ranging from 0.5 up to 10.0 percent by weight, by using ultrasonic dispersion of lead monoxide in the polycarbonate solution, followed by solution casting. For these composites, beta radiation shielding properties such as mass attenuation coefficient, range of beta particles and half value layer thickness for beta particles from low activity thallium −204 and yttrium – 90 radioactive sources have been found experimentally and computationally, along with the mass density and modified atomic number of the composite material. Two different computational methods, namely, Baltakment’s empirical formula method and Bragg’s mixture rule have been used to calculate the theoretical value of mass attenuation coefficient, whereas Katz and Penfold relationship has been used to calculate the range of the beta particles obtained from these sources in the prepared composite films. The results obtained are discussed.

3D printed bidirectional rotatory hybrid nanogenerator for mechanical energy harvesting

In the world of automotive technologies, a tremendous amount of small-scale rotational energy is wasted and not being converted into a usable energy form. A rotatory triboelectric nanogenerator can be a fortune technology to harvest such waste mechanical energy and convert it into electricity. In this regard, we developed a fully three-dimensional (3D) printed bidirectional rotatory hybrid nanogenerator (BR-HNG) to convert waste rotational energy into electricity, via a contact and separation mode mechanism. Initially, a single HNG was fabricated with porous sodium niobate and polydimethylsiloxane polymer (i.e., NaNbO3/PDMS) composite film, which was operated vertically against the aluminum to optimize a high and stable electrical output. After the robust and stability test of the single HNG, multiple HNGs were integrated into a 3D printed bidirectional rotatory frame to harvest the rotational energy. It was observed that the BR-HNG had a stable and high electrical direct current voltage of 37.5 V. Furthermore, the BR-HNG was attached to a bicycle to harvest the rotational energy while bicycling in everyday human life and power up various portable electronics.

Tailoring the structural and optical features of PtCl4@ PVA polymeric composite films for optical applications

The PtCl 4 @PVA composites films were prepared by casting an aqueous solutions technique. Based on the effect of PtCl 4 concentrations, the PVA structure was modified from semi-crystal to amorphous material. Corresponding to FTIR and XRD, PtCl 4 is interlinked with a hydroxyl group in the matrix. Both refractive index and extinction coefficient were calculated in the UV–Vis region. The energy gaps of PtCl4@PVA composites films were shifted from 2.58 to 2.43 eV with increasing the PtCl 4 concentrations. Also, the real and imaginary dielectric constants were studied. Furthermore, the volume energy loss function and the surface energy loss function were calculated. Two types of lasers with different input power, as optical limiters, are used to examine the response of PtCl 4 @PVA films with different PtCl 4 concentrations. The present results show that the PtCl 4 @PVA films rely on laser power to attenuate green lasers and He–Ne lasers. The outcome of PtCl 4 @PVA films can be extended to optical applications such as laser filters CUT-OFF. • PtCl4@PVA composites films with various concentrations of PtCl4 were achieved. • The increase in PtCl4 doping improves the optical properties of PtCl4@PVA films. • PtCl4@PVA film is considered an excellent optical material and optical limiter.

Visible Light-Generated Antiviral Effect on Plasmonic Ag-TiO2-Based Reactive Nanocomposite Thin Film.

The recent coronavirus pandemic pointed out the vulnerability of humanity to new emerging infectious diseases. Experts warn that future pandemics may emerge more frequently with greater devastating effects on population health and the world economy. Although viruses are unable to propagate on lifeless surfaces, they can retain their infectivity and spread further on contact with these surfaces. The objective of our study is to analyze photoreactive composite films that exert antiviral effects upon illumination. Reactive plasmonic titanium dioxide-based polymeric nanocomposite film was prepared with a thickness of 1–1.5 µm, which produces reactive oxygen species (ROS) under visible light irradiation (λ ≥ 435 nm). These species are suitable for photooxidation of adsorbed organic molecules (e.g., benzoic acid) on the nanocomposite surface. Moreover, high molecular weight proteins are also degraded or partially oxidized in this process on the composite surface. Since the Ag0-TiO2/polymer composite film used showed excellent reactivity in the formation of OH• radicals, the photocatalytic effect on high molecular weight (M = ∼66.000 Da) bovine serum albumin (BSA) protein was investigated. Given that changes in the structure of the protein were observed upon exposure to light, we assumed virucidal effect of the illuminated photoreactive composite film. We tested this hypothesis using an airborne-transmitted herpesvirus. As a result, we obtained a drastic decrease in infection capability of the virus on the photoreactive surface compared to the control surface.

Nonlinear optical fullerene and graphene-based polymeric 1D photonic crystals: perspectives for slow and fast optical bistability

Nonlinear optical (NLO) properties of materials can be enhanced by assembling them as thin polymer composite films alternating with other polymers and forming dielectric mirrors, 1D photonic crystals (1DPCs), wherein the input light intensity is increased. Based on the poly(vinyl carbazole) (PVK) and poly(vinyl alcohol) (PVA) contrasting polymer pair, variants of such structures, with graphene and fullerene in their high-index layers, have been produced. Their optical switching characteristics have been studied with ns, cw, and quasi-cw fs laser sources in the IR and with a fs laser in the visible range. We have demonstrated slow optical bistability in the polymeric 1DPCs determined by the thermal expansion of polymer composites at intensities over 100 W / c m 2 as well as fast and ultrafast optical switching due to thermo-optic and Kerr nonlinearities, respectively. Characteristic nonlinear refractive coefficients responsible for these processes were found to be n 2 t o ∼ 10 − 1 c m 2 / G W and n 2 K e r r ∼ 10 − 4 c m 2 / G W . A subpicosecond fast spectral shift of the 1DPC bandgap has been found. Our results and analysis provide a clear picture of the NLO behavior of 1DPCs at different time scales. The results stimulate the subsequent design of ultrafast switches and bistable memory cells based on polymeric 1DPCs whose micrometer thickness and flexibility offer promise for implementation into fiber and microchip configurations.

Enhanced magnetoelectric coupling response in hot pressed BiFeO3 and polymer composite films: Effect of magnetic field on grain boundary and grain resistance

We report the effect of grain boundary resistance (GBR) and grain resistance (GR) on the magnetoelectric coupling in the multiferroic composite thick films of BiFeO3 (BFO) nanocrystalline powder and poly vinylidene-fluoride (PVDF) polymer. These composite thick films of thickness ∼ 0.2 mm were prepared via hot pressing with the weight ratio of BFO powder and PVDF polymer as 70:30 (abbreviated as BFO70), 60:40 (abbreviated as BFO60), 50:50 (abbreviated as BFO50) and 40:60 (abbreviated as BFO40), respectively. Impendence investigations (Cole-Cole plots) of these thick films demonstrate that the GBR is significantly changed on the application of magnetic field (8 kOe) in comparison to the GR. Our results indicate that the GBR plays an important role in strengthening of magnetoelectric (ME) effect in BFO-PVDF system. In addition, the ME coupling study indicates that the BFO50 sample shows better results (α33 ∼ 2.7 mV/cm-Oe) and may be suitable for device and sensor applications.

Enhanced dielectric response of ternary polymeric composite films via interfacial bonding between V2C MXene and wide-bandgap ZnS

Increasing the dielectric constant of polymer/sulfide ceramic composites by using wide-bandgap semiconducting sulfide ceramic fillers like ZnS is difficult because of their low interface polarization. To increase the dielectric constant, in this study, ternary polymer-based composite films were designed and fabricated using a hybrid filler consisting of shell-like ZnS particles and core-like V2C MXene particles. First, V2C MXene with a multi-layered structure was synthesized from the simplest raw materials followed by the in-situ hydrothermal growth of ZnS particles around the V2C particles. Then, binary polymer/ZnS and ternary polymer/V2C–ZnS composites were fabricated, and their dielectric, conductive, and electrical breakdown properties were investigated. Finally, the effect of interfacial bonding between the V2C and ZnS phases was investigated by density functional theory calculations, and the contribution of V2C/ZnS interfacial bonding to the higher dielectric constant of the ternary composites than that of the binary composites was explained. The ternary composites exhibited balanced electrical properties suitable for energy storage applications. The ternary composite with 10 wt% hybrid filler loading exhibited a high dielectric constant of ~52, a low dielectric loss of ~0.11 at 100 Hz, and a high electrical breakdown strength of ~202 MV m−1. This study paves the way for the facile fabrication of high-performance composite dielectrics for application in advanced capacitors.

Blue-Shifting Mechanofluorochromic Luminescent Behavior of Polymer Composite Films Using Gelable Mechanoresponsive Compound

Mechanochromic luminescent dyes change their luminescence color upon exposure to external mechanical stimuli. In this study, we synthesized a liquid crystalline mechanochromic luminescent dye containing a terminal cholesterol molecule. The dissolution of the dye in 1,4-dioxane resulted in the formation of a gel. The luminescence of the xerogel obtained from the dioxane solution changed from green to blue upon grinding, indicating mechanochromic luminescence behavior. The anisotropic patterning of short-wavelength-shifted luminescence color change by directional handwriting on surface layer of liquid crystal was successfully demonstrated. Furthermore, blue-shifting mechanoresponsive polymer composite surface was fabricated by using the luminophore.

Tailored magnetoelectric coupling in magnetically oriented polymer-based iron fiber composite

Artificial multiferroics magnetoelectric (ME) polymer composite films exhibiting collective ferroelectric and magnetic orderings are gaining attractive for the use of flexible ME devices. Herein an anisotropic polymer-based ME composites films is developed, composed of magnetically oriented polycrystalline iron fiber (Fef) and poly(vinylidene fluoride-co-trifluoroethylene) P(VDF–TrFE). The structure, ferroelectric, piezoelectric, magnetic, and ME properties was systematically investigated. Both Fef fillers content and magnetic field direction determined the ME voltage coefficient, magnetical polarization and dielectric response in anisotropic P(VDF-TrFE)–Fef composites. Specifically, the composite with 16% filler loading delivers a peak ME value of 44.5 mV·cm−1·Oe−1 with magnetic field exerted along the fiber axial alignment direction. Such extracted results may encourage a way to optimize flexible composite in anisotropic contactless sensing and detecting applications.

Flexible light-responsive self-healing polymeric composite film based on two-dimensional MoS2 - organic halide perovskite longitudinal heterostructure

Organic hybrid perovskite (OHP) is one of the most attractive optical absorbable and reactive materials. However, excellent light-responsive self-healing polymeric composite film based on OHP is difficult to obtain. Here, four two-dimensional (2D) OHP with different typical sizes and morphologies were prepared by regulating with four different typical diamines, and the novel scale-like plate-stack 2D MoS2-OHP longitudinal heterostructure was fabricated. Then, a valid structure strategy, utilizing 2D MoS2-OHP as the light-responsive material and self-healing polyurethane (PU) as polymer matrix, is firstly developed to realize high performance light response. Among these light responsive self-healing polymer materials, the MoS2-OHP-3/PU composite film exhibited excellent figures of merit, including high light stimulation response (ΔR value was 70.0589 MΩ), strong tensile strength value (8.06 ± 0.05 MPa), high maximum elongation (467 ± 13.82%), high self-healing efficiency (80% for mechanical properties, 95% for light-response) and ultra-high humidity stability (86% for light response, 81.89% mechanical properties). This work provided a novel method and a feasible substrate for the development of self-healing, flexible and scalable intelligent response soft materials.

ZnO Polymeric Composite Films for n-Decane Removal from Air Streams in a Continuous Flow NETmix Photoreactor under UVA Light.

Polymeric composite films have been explored for many photocatalytic applications, from water treatment to self-cleaning devices. Their properties, namely, thickness and porosity, are controlled mainly by the preparation conditions. However, little has been discussed on the effect of thickness and porosity of polymeric composite films for photocatalytic processes, especially in gas phase. In the present study, different preparation treatments of ZnO-based polymeric composite films and their effects on its performance and stability were investigated. The polymeric composites were prepared by solution mixing followed by non-solvent induced phase separation (NIPS), using poly(vinylidene fluoride) (PVDF) as the matrix and ZnO-based photocatalysts. Different wet thickness, photocatalyst mass, and treatments (e.g., using or not pore-forming agent and compatibilizer) were assessed. A low ZnO/PVDF ratio and higher wet thickness, together with the use of pore-forming agent and compatibilizer, proved to be a good strategy for increasing photocatalytic efficiency given the low agglomerate formation and high polymer transmittance. Nonetheless, the composites exhibited deactivation after several minutes of exposure. Characterization by XRD, FTIR-ATR, and SEM were carried out to further investigate the polymeric film treatments and stability. ZnO film was most likely deactivated due to zinc carbonate formation intensified by the polymer presence.

Accelerated CO2 transport by synergy effect of ionic liquid and Zn particles

In this experiment, an ionic liquid (BMIMBF4) was used to prepare a composite membrane containing ZnO nanoparticles. Our previous study indicated that a composite membrane composed of ZnO and the ionic liquid (BMIMBF4) showed high CO2/N2 separation performance with a GPU of 101 and a selectivity of 42.1. The oxide layer of ZnO nanoparticles with the imidazolium ring of ionic liquid (BMIMBF4) increased the solubility of CO2 and acted as a barrier for N2, leading to an overall improvement in the performance. However, the liquid film was absorbed into support over time and became thickened, leading to instability. In order to solve this problem, a solid polymer composite film was manufactured and investigated as a solution. The polymer PEBAX2533 was used as a polymer matrix to produce a composite membrane capable of showing both high separation performance and long-term stability.

Solvent Free Synthesis of the Carboxymethyl Cellulose/Polyaniline Silver nanoparticles Composite thin Films

Flexible polymer composite films comprising carboxymethyl cellulose (CMC), polyaniline (PANI) and silver nanoparticles (AgNps) were successfully fabricated through an in-situ polymerization method. The composite structure of the fabricated film was confirmed by X-ray diffraction and infrared spectroscopy, indicating the successful incorporation of AgNps into the CMC/PANI blend. The scanning electron microscope (SEM) images have indicated a homogenous loading and dispersion of AgNps into the CMC/PANI blend. The optical parameters such as band gap (Eg) was determined using the UV optical absorbance. The inclusion of AgNps and PANI has enhanced the optical properties of the CMC polymer, providing a new composite suitable for energy conversion systems, solar cells, biosensors, and nonlinear optical applications. The electrical properties of the composites were examined using temperature-dependent DC conductivity within 293–373 oK. The composites with increasing AgNps in the PANI-CMC composites shows the enhancement in the higher crystallinity, thermal stability, and higher electrical conductivity. the antimicrobial properties were evaluated with the aid of agar diffusion tests. The results showed distinct zones of inhibition against major microorganisms.

Physical and chemical modifications of cellulose fibers for food packaging applications

Cellulose fibers have gained considerable interest for use as gas barriers and reinforcing fillers in food packaging materials because of their interesting properties, including biodegradability, low density, nontoxicity, and low cost. Although modifications of cellulose nanomaterials for reinforcing applications have been reviewed in the literature, they suffer from a lack of comparative results, and the modifications related to food packaging applications have not been covered yet. This study reviews physical and chemical methods used to improve oxygen and water barrier properties, water uptake, mechanical strength, and transparency of different food packaging films of cellulose nanomaterials, and provides comparative results. Heat treatment, esterification, and TEMPO-mediated and periodate oxidation are the most common methods used to improve the barrier properties of free-standing, bilayer, and composite films prepared from cellulose nanomaterials. Modification using silane compounds is a well-established method for improving the mechanical properties of cellulose fibers and polymer composite films.

Strong Polarized Photoluminescence CsPbBr3 Nanowire Composite Films for UV Spectral Conversion Polarization Photodetector Enhancement.

In this work, we proposed a fluorescence conversion layer with polarization characteristics to enhance UV polarization detection for the first time. To achieve this goal, the colloidal lead halide CsPbBr3 nanowires (NWs) with appropriate lengths were synthesized by the method of ultrasonication synthesis assisted by the addition of hydrobromic acid (HBr) ligands. By adding HBr, the properties of synthesized NWs are improved, and due to the controllable perovskite-stretched NWs, polymer composite films were fabricated, which can generate photoluminescence (PL) with strong polarization. The optimized stretched composite film can achieve a polarization degree of 0.42 and dichroism ratio (I∥/I⊥) of 2.49 at 520 nm. Based on this film, an imaging system with polarization-selective properties and efficient UV spectral conversion was developed. The spectrum conversion of 266 to 520 nm luminescence wavelength was realized and sensitive to the polarization of incoming 266 nm UV light. The experimental results also showed that the response after spectral conversion is greatly improved, and different responsivities can correspond to different polarization states. This imaging system overcomes the insufficiency of the conventional charge coupled device (CCD), which makes it difficult to receive the optical signal for high-quality UV imaging. The use of light conversion films with polarization characteristics for polarized UV imaging is of great significance for improving the detection of solar-blind UV bands and the recognition of military targets.

Preparation of flexible, highly conductive polymer composite films based on double percolation structures and synergistic dispersion effect

AbstractWe studied for the first time the synergistic dispersion effect of the carbon nanotube (CNT)/graphene (Gr) and polypropylene (PP)/polycarbonate (PC) (1:1) double percolation structures on conductive polymer composites (CPCs). PP/PC/CNT/Gr films with different CNT/Gr ratios are prepared by melt blending and hot pressing. Results showed that a CNT/Gr ratio of 1:1 facilitated the creation of co‐continuous double percolation structures of matrices, and the electronic conductivity reached 33.11 S/m, which was five times greater than that of the matrices containing only CNT. Results showed that the synergistic dispersion effect and the co‐continuous double percolation structures provided the matrices with conductivity through an additive effect. Meanwhile, PP/PC/CNT/Gr composite films possessed good thermal stability and hydrophobicity. They also did not exhibit thermal degradation at 300°C and had a water contact angle of 94.5°. However, PP and PC were incompatible, causing considerable brittleness of composite films macroscopically, and the films can hardly curve. To respond to this downside and improve the flexibility, a small amount of thermoplastic polyurethane (TPU) was added to the system. The presence of TPU helped combining the two materials in different phases, thereby strengthening the continuity. However, the presence of TPU adversely affected the double percolation structures and dispersion state of fillers, and subsequently decreased the conductivity.