Hybrid Composite Films Research Articles

Synergistic effect of hybrid hydroxylated boron nitride and cellulose nanocrystals for enhancing the thermal, mechanical, and hydrophobic properties of composite film

AbstractHybrid composite films are largely preferred over neat films because of their superior thermal, mechanical, chemical, and hydrophobic properties. The hybrid composite film has a wide range of use, including space, defense, electronics, packaging, and engineering applications. Fabricating multifunctional hybrid composite films with biodegradable polymer and biodegradable filler such as cellulose nanocrystals has become popular in recent years as an alternative to conventional plastics. In this paper, hybrid hydroxylated boron nitride (BN) nanoparticles with CNC nano‐filer reinforced composite PVA films were fabricated. The obtained composite films were characterized for morphological, chemical, physical, thermal, and hydrophobic properties. The morphological analysis indicates that the hybrid nano‐filler was well dispersed in the poly(vinyl alcohol) (PVA) matrix. The reaction and hydrogen bond interactions between CNC and BN in composite films are confirmed by the Fourier transform infrared spectroscopy and x‐ray diffraction pattern. The contact angle method is used to confirm the enhancement of the hydrophobic property. The physical properties of the composite films and neat PVA film were analyzed by tensile test method using a universal testing machine. The thermal stability of the neat PVA film and the composite films were analyzed by the thermo‐gravimetric analysis method. The effect of hybridization of nanoparticles on the thermal, mechanical, and hydrophobic properties was studied. The hybrid composite film with enhanced properties allows it for multifunctional applications.

Porous fluorine-doped tin oxide-anchored vanadium oxide films for multi-functional highly capacitive electrochromic layers

Electrochromic (EC) devices have been studied in recent decades as devices for optical property changes and energy-saving technologies, which has broadened their applications to include smart windows, sunglasses, and rear-view mirrors. Recently, multifunctional EC energy storage devices have attracted global attention because they can store and release energy during color changes. Herein, we demonstrate a hybrid composite structure of porous fluorine-doped tin oxide (FTO) microspheres on vanadium oxide films. Porous FTO microspheres were successfully synthesized using solvent-assisted ultrasonic spray pyrolysis. Vanadium oxide precursor solutions for the spin-coating process were prepared with porous FTO microsphere contents of 0, 1, 2, and 3 wt%. The hybrid composite EC energy storage film with 2 wt% porous FTO (V2O5-FTO2) exhibited superior EC and energy storage performances of widened transmittance modulation (53.79 % at 415 nm) and competitive specific capacitance (486.3 F/g at a high current density of 10 A/g) with high cyclic stability of 87.96 % up to 500 cycles. Thus, the suggested V2O5-FTO hybrid structure demonstrates feasibility as a promising research strategy for developing multifunctional highly capacitive electrochromic layers.

Gas Sensing and Thermoelectric Properties of Hybrid Composite Films Based on PEDOT:PSS and SnO or SnO2 Nanostructures

In this work poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with ethylene glycol (EG) and SnO or SnO2 nanoparticles are mixed in a controlled way to create hybrid composites in form of thin films via spin coating. The potential applicability of these composites as gas sensors and as thermoelectric materials is tested, while insights are achieved in the comprehension of the underlying physical mechanisms. The addition of SnO in the composite promotes an enhancement in the chemoresistive response upon ethanol gas exposure at room temperature. Based on the Seebeck coefficient and Hall effect measurements, improvement of the power factor (PF) is achieved by the controlled addition of SnO nanoparticles in the composite. These results promise well for progress in the use of hybrid composites in these areas paving the way for future improvement in research on hybrid electronics, involving improved scalability and energy saving.

Sustainable fabrication of bio-derived hybrid films using biomolecules extracted from animal skin

In this work, we report preparation of bio-derived hybrid composite films from the protein extracted from raw trimmings emulsified with lipid obtained from tannery fleshing. Effect of varying concentrations of lipid at 10%, 20% and 40% v/w, homogenization rate and plasticization effect of lipid without glycerol were studied on the films’ functionality. Chemical composition of the developed films was determined using ATR-FTIR. The influence of emulsification conditions on the surface topography was studied by scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). FTIR and microscopic evaluation indicated the heterogeneity of the films, which is caused due to phase separation. Mechanical, spectral and thermal studies revealed that the lipid addition without glycerol had an anti-plasticization effect caused by the irregularly dispersed solid lipid phase. Films prepared with 40% v/w lipid at 8000 rpm homogenization speed (TF40-8K) showed reduced water vapor permeability of 1.33 × 10-8 g/m.s.Pa and increased water contact angle of 82.2º as compared to control films. Transparency, color and optical characteristics indicated that the films became less transparent with increasing lipid concentrations. Valorization of different biomolecules from industrial wastes for preparation of eco-friendly plastics will be environmentally sustainable with application potential in agricultural mulching, packaging and bioelectronics.

Improved output performance of hybrid composite films with nitrogen-doped reduced graphene oxide

In this research, graphene-based ceramic/polymer hybrid composite films for energy harvesting devices were prepared and analyzed. Nitrogen-doped reduced graphene oxide (N-rGO) conductive elements were embedded in a ceramic/polymer matrix as floating electrodes to form a micro-capacitor composite structure. The effects of nitrogen atom substitution on the rGO materials were investigated and their conducting properties improved. The employment of rGO- and N-rGO-based floating electrodes resulted in the formation of micro-capacitors and an increase in the potential energy of the composite films. The increase in the potential energy consequently increased the output energy of the energy harvesters. The highest voltage and energy density of the composite films were 8.5 V and 1.46 mJ/cm3, respectively, for the N-rGO based ceramic/polymer composite film.

Improving the electrochemical stability of AZ31 Mg alloy in a 3.5wt.% NaCl solution via the surface functionalization of plasma electrolytic oxidation coating

The unique interactions between hexadecanoic acid (HA) and albumin (ALB) molecules on the surface of the porous layer of AZ31 Mg alloy were exploited to fabricate a novel hybrid composite film with excellent electrochemical stability in a 3.5 wt.% NaCl solution. Herein, the inorganic layer (IL) obtained by plasma electrolytic oxidation of AZ31 Mg alloy in an alkaline-phosphate-WO3 electrolyte was soaked in an organic solution composed of ALB and HA for 10 and 24 h at 60 °C. Although albumin and HA may coexist on the same surface of IL, the higher reactivity of ALB molecules would prevent the formation of a thick layer of HA. The donor-acceptor complexes formed due to the unique interactions between ALB and/or HA and IL surface would reduce the area exposed to the corrosive species which in turn would efficiently protect the substrate from corrosion. The porous structure of the IL would provide preferable sites for the physical and chemical locking triggered by charge-transfer phenomena, leading to the inhomogeneous nucleation and crystal growth of a flowery flakes-like organic layer. DFT calculations were performed to reveal the primary bonding modes between the ALB, HA, and IL and to assess the mechanistic insights into the formation of such novel hybrid composites.

Study of thermoelectric properties in the PEDOT:PSS/Te double-layer thin film devices

The research on the organic hybrid composites have been regarded as important developing direction in the field of thermoelectric fields, which combine the advantages of organic thermoelectric materials and inorganic thermoelectric materials. In this paper, the thermoelectric properties of Tellurium (Te) and Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid composite thin film and double-layer structured of PEDOT/Te thin film are studied, separately. We found that the PEDOT:PSS/Te double-layer structured thin film thermoelectric devices can greatly improve conductivity and Seebeck coefficient of PEDOT:PSS compared with the hybrid structure of PEDOT:PSS thermoelectric devices. We thought that the semi-metallicity of PEDOT:PSS and Te forms an ohmic contact interface, which is advantageous to charge transfer, so the double-layer structure of thin film devices possess a better carrier transport channels by the interface effect than hybrid structure devices. On the other hand, the C–V results also confirmed that the interfacial charge accumulation in the PEDOT:PSS/Te double-layered thin-film device, when the temperature rises, the Fermi level close to the conduction band as the temperature increases, leading to the number of high-energy carriers increase at the interface, which effectively improves the Seebeck coefficient of PEDOT:PSS. Our research provide experimental and theoretical support for the development of thin-film thermoelectric materials and devices.

Room temperature hydrogen sensing with polyaniline/SnO2/Pd nanocomposites

In this work, we report unique hybrid composite film fabricated with the amalgamation of metal, semiconductor and polymers for hydrogen sensing application at room temperature. Fabrication of a novel nanocomposite film based on tin oxide (SnO 2 ) nanosheets with polyaniline (PANI) doped with palladium (Pd) is performed using the hydrothermal synthesis technique. Functional aspects of the fabricated films are investigated with XRD, Raman spectra, FESEM, and FTIR spectral analysis. Interactions of the H 2 gas molecules with SnO 2 , SnO 2 -Pd, PANI, PANI-SnO 2, PANI-SnO 2 -Pd nanocomposite are also theoretically studied. Using first-principles density functional theory, the effects of gas adsorption on the electronic and transport properties of the sensor are examined. The computations show that the sensitivity of the SnO 2 to the H 2 gas molecules is considerably improved after hybridisation with Pd and, the sensitivity of the PANI to the H 2 gas molecules is considerably improved after hybridisation with SnO 2 .Gas sensing characteristics of fabricated films of SnO 2 , PANI and composite of SnO 2 /PANI/Pd are also experimentally investigated at room temperature with varying concentration level ranging from 50 to 400 ppm. The highest sensitivity among all the films at room temperature has been observed as ~540% for the SnO 2 /Pd film at 0.4% of the target gas and performance factor (the ratio of response percentage to total cycle time) is evaluated highest in Pd doped PANI-SnO 2 film. Our results reveal the promising future of SnO 2 , PANI and Pd associated hybrid films in the development of ultra-high sensitive gas sensors. • We report unique hybrid composite film fabricated with the novel nanocomposite film based on tin oxide (SnO 2 ) nanosheets, polyaniline (PANI) doped with palladium (Pd) for room temperature hydrogen sensor. • Results obtained from the first-principles density functional theory show that the sensitivity of the SnO 2 to the H 2 gas molecules is considerably improved after hybridisation with Pd and the sensitivity of the PANI to the H2 gas molecules is considerably improved after hybridisation with SnO 2 . • The highest sensitivity among all the films at room temperature has been observed as ~540% for the SnO 2 /Pd film at 0.4% of the target gas and performance factor is evaluated as highest in Pd doped PANI-SnO 2 film.

Highly reliable memristive devices with synaptic behavior via facilitating ion transport of the zeolitic imidazolate framework-8 embedded into a polyvinylpyrrolidone polymer matrix

Composite-based memristive devices have attracted tremendous attention as promising applications in futuristic information technologies due to their synergetic effects between the solid filler and the polymer matrix for enabling versatile information processing. Here, we demonstrate the digital data storing and the analog data processing capabilities of artificial synapses consisting of zeolitic imidazolate framework-8 (ZIF 8):polyvinylpyrrolidone (PVP) hybrid nanocomposites. The composite-based devices exhibited excellent resistive switching behaviors with reliable operating voltage (1.24 ± 0.12 and −2.75 ± 0.33 V) and a large RON/ROFF ratio (7.8 × 103) for 500 repeated resistance switching cycles. The fundamental synaptic behaviors in neuromorphic systems, such as potentiation/depression, transitions from short-term to long-term memory, and the biological learning rules of spiking time-dependent plasticity, were imitated. Finally, via structural and theoretical analyses, we demonstrated that the excellent memristive behaviors were due to the ion trapping effect of the ZIF-8 nanoparticles in the ZIF-8:PVP hybrid composite film.

62‐9: Invited Paper: Hybrid Composite Films with Perovskite Quantum Dots and Red Phosphors for LCD Display Backlights

Perovskite quantum dots films (PQDF) are emerging as low‐cost alternatives to improve the color gamut of liquid crystal display (LCD) backlights due to their narrow half peak width. In this paper, hybrid composite films with green perovskite quantum dots (PQDs) and red rare earth phosphors were combined in a dual layer film for LCD backlight display applications. By combining the in‐situ fabricated green emissive PQDF with KSF phosphor or red nitride phosphor (NP), we prepared hybrid composite films of green PQDF and red phosphors with high brightness and wide color gamut. The color gamut of PQDs‐KSF is 83.1% of Rec. 2020 due to the narrow full‐width‐at‐half‐maximum of PQDs and KSF phosphors. These composite films have great potential in the application of LCD backlights.

Effect of the Biodegradable Compounds Composition with Monoglycerides on Mechanical Properties

The purpose of this work is to improve the production technology of biodegradable hybrid compositions based on low-density polyethylene with thermoplastic starch and new plasticizer–distilled monoglyceride and determination of the composition effect on mechanical properties. Starch was plasticized with a mixture of glycerol and distilled monoglycerides, instead of the known sorbitol. This article describes methods for producing biodegradable hybrid composite films based on polyethylene and thermoplastic starches (corn, pea and rice) with a mass ratio of components, respectively, 40:60÷60:40 and their mechanical properties. Properties and structure of composite films are studied using test methods, rheological parameters, optical microscopy, and differential scanning calorimetry. The advantages of using monoglycerides as a plasticizer in thermoplastic starch/ polyethylene compositions have been demonstrated. Composites obtained using distilled monoglycerides and thermoplastic corn, pea and rice starch have been characterized by 62-81% higher values of critical stress and 62-93% elongation at rupture, compared with BHC containing sorbitol. The thickness of biodegradable hybrid composite films with monoglycerides is 55-86% less than that of films containing sorbitol in composition of thermoplastic starch. Higher elongation values at rupture and lower film thickness will ensure more effective destruction in environment and more cost-efficient use in packaging.

Design and fabrication of Pt-free FeNi2S4/rGO hybrid composite thin films counter electrode for high-performance dye-sensitized solar cells

In this work, we synthesized FeNi2S4/rGO composites as Pt-free counter electrode (CE) by one step hydrothermal method. Complete investigations of phase evolutions by XRD patterns and TEM indicate spinel structure with nanosheets and nanospherical morphologies. The individual spherical-shaped nanoparticles (30–35 nm) of FeNi2S4 were exploited on the 2D ultrathin rGO nanosheets surface. This is useful for the provision of further electrolyte adsorptions and responsive electrocatalytic sites. The DSSC constructed with FeNi2S4/rGO hybrid composite CE showed a conversion efficiency of 9.98%, better than that by FeNi2S4 CE (4.87%) and also commercial Pt (6.21%). The outstanding efficiency of the FeNi2S4/rGO hybrid composite CE is even better than commercial Pt and is an effective alternative to Pt CE in the DSSCs.

Multifunctional hybrid composite films based on biodegradable cellulose nanofibers, aloe juice, and carboxymethyl cellulose

Cellulose nanofibers isolated from birch kraft pulp were incorporated into carboxymethyl cellulose-based films as a mechanical strength enhancer, and aloe juice was used as an antibacterial agent. Fourier-transform spectroscopy was performed and indicated the presence of hydrogen bonds that enhance the intermolecular interactions between the carboxymethyl groups and cellulose nanofibers in the prepared film. The incorporation of 5 wt% cellulose nanofibers significantly increased the tensile strength to 21-fold that of films lacking the nanofibers. The addition of aloe juice resulted in films with strong antibacterial activities against E. coli and S. aureus that prolong the shelf life of fresh pork. Cellulose nanofibers and aloe juice both increase the thermal stability and glass transition temperature of the carboxymethyl cellulose-based films, with little effect on the whiteness, transmittance, and wettability of these films. The rheological properties were characterized and revealed competitive interactions between cellulose nanofibers, carboxymethyl cellulose-based films, and aloe juice. The results show that the modified film is a promising material for use in food packaging.

Plasma-Initiated Graft Polymerization of Acrylic Acid onto Fluorine-Doped Tin Oxide as a Platform for Immobilization of Water-Oxidation Catalysts.

The discovery of new and versatile strategies for the immobilization of molecular water-oxidation catalysts (WOCs) is crucial for developing clean energy conversion devices [e.g., (photo)electrocatalytic cells for water splitting]. The traditional approach for surface attachment to transparent conductive oxides [e.g., fluorine doped tin oxide (FTO)] is via synthetic modification of the ligand architecture to incorporate functional groups such as carboxylic acids (-COOH) or phosphonates (-PO3H2) prior to immobilization. However, challenges arising from desorption and the cumbersome derivatizations steps have limited the scope and applications of surface-bound WOCs. Herein, we report the successful immobilization of underivatized Ru(II)-based WOCs (Ru-Cat1 = [Ru(tpy) (bpy) (H2O)]2+ (tpy = 2,2':6'2″-terpyridine and bpy = 2,2'-bipyridine) and Ru-Cat2 = [Ru(Mebimpy) (bpy) (H2O)]2+ (Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl) pyridine)) and the Ru(II) polypyridyl chromophore Ru-C3 = [Ru(bpy)3]2+ onto a FTO plasma-grafted poly(acrylic acid) surface (PAA|FTO). Various characterization techniques such as attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and cyclic voltammetry measurements provide evidence for the plasma-induced grafted PAA|FTO film and immobilization. Surface stability and electrocatalytic properties of these new hybrid composite films upon cycling were investigated at different pH values. Immobilized Ru-Cat1 and Ru-Cat2 onto PAA|FTO displayed pH-dependent (RuIII/RuII) couples and onset potentials indicative of PCET (proton-coupled electron transfer) reactions. Based on cyclic voltammetry results and spectroscopic monitoring, the immobilized WOCs Ru-Cat1 and Ru-Cat2 exhibited a higher surface stability in neutral aqueous solutions relative to Ru-C3 upon electrochemical oxidation. We attribute the surface PCET and stability to the presence of a water ligand in the coordination sphere of immobilized Ru-Cat1 and Ru-Cat2 which can H-bond with negatively charged carboxylate groups of the cross-linked PAA brushes. Our findings demonstrate that the plasma-grafted polymeric network onto FTO offers a versatile platform to directly anchor unmodified homogeneous WOCs or chromophores for potential applications in solar-to-fuel energy conversion.

Development of geopolymer derived from slag waste based composite film on cotton fabric: A preliminary approach for flame retardant behavior

Organic-inorganic hybrid composite films with a geopolymer and organic polymers (sodium polyacrylate, polytetrafluorethylene, and polyurethane) were prepared using a facile method for application as flame retardant coatings. The geopolymer paste was successfully synthesized by adding a mixture of metakaolin and slag into an alkali solution. The structural and morphological properties of the barrier films were investigated using Fourier-transform infrared spectroscopy and scanning electron microscopy. The films showed the Si-O and Si-Al peaks characteristic of the geopolymer. The microstructural examination revealed that the films consisted of irregular particles. With an increase in the geopolymer amount, the flexural and compressive strengths of the samples decreased. The tensile strength, thermogravimetric analysis and flame retardant properties of the composite paste were investigated. The films showed a tensile strength of 0.15–0.30 MPa. The composite film coated onto cotton surface was thermally stable up to 200 °C. The cotton (C) and the mixture of cotton and polyester (M) substrates coated with the barrier film showed the char lengths of 5–8 and 4–7 cm, respectively. The geopolymers synthesized using slag and metakaolin exhibited excellent flame retardant properties on the cotton fabric. Hence, these films were found to be promising candidates for flame retardant applications.

Organic thermoelectric devices with PEDOT:PSS/ZnO hybrid composites

Organic thermoelectric devices (OTEDs) are considered one of the most promising thermoelectric devices for harvesting electricity from low-temperature heat sources. Here it is demonstrated that the hybrid composites of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and zinc oxide (ZnO) particles enhance the performances of OTEDs due to the improved electrical conductivity by the bridging role of ZnO particles. The detailed study showed that the addition of ZnO particles to the aqueous solutions of PEDOT:PSS led to the increased viscosity owing to the specific interactions between sulfonic acid groups in PSS and hydroxyl groups (and/or zinc cations) in ZnO. The OTEDs with the PEDOT:PSS/ZnO hybrid composites with 70 wt% of 45 μm-sized ZnO particles exhibited 0.55 nW, which is ca. 7.8 times higher power than the devices with the pristine PEDOT:PSS sheets (0.07 nW). The wearable thermal sensors with the PEDOT:PSS/ZnO hybrid composite films showed fast thermoelectric responses toward heat and cool sources.

Development of technology for producing biodegradable hybrid composites based on polyethylene, starch, and monoglycerides

Objectives. This work aimed to develop technology to produce biodegradable hybrid composite (BHC) films based on low-density polyethylene (LDPE) 115030-070 and thermoplastic starches (TPS) of various origins (corn, pea, and rice), with distilled monoglycerides as the plasticizer. The properties of the produced BHC films were studied and the optimal native starch : glycerol : monoglycerides ratio is proposed.Methods. TPS and BHC films based on this material were produced from different types of native starches in laboratory extruders (Brabender and MashPlast, Russia), and the extruded melts were subjected to ultrasonic vibrations. The structure and appearance of the BHC films were studied using scanning electron microscopy and rheology. Their biodegradability was assessed by immersing them in biocompost for three months. To evaluate the mechanical performance of the BHC films produced with and without ultrasound, the changes in tensile stress and elongation at break were determined during the biodegradation process.Results. The BHC films had a homogeneous structure, except small agglomerates (non-melted starch grains), which did not reduce their quality. The films with monoglycerides had high tensile strength, which was comparable with low-density polyethylene. After removing samples of the BHC films from the biocompost, their tensile strength decreased by 20%, which shows their biodegradability.Conclusions. The produced biodegradable composite films and the technology used to produce them will be applicable for the packaging industry to reduce environmental impact.

New Insight on Photoisomerization Kinetics of Photo-Switchable Thin Films Based on Azobenzene/Graphene Hybrid Additives in Polyethylene Oxide

In this work, we reported a new insight on the kinetics of photoisomerization and time evolution of hybrid thin films considering the azo-dye methyl red (MR) incorporated with graphene accommodated in polyethylene oxide (PEO). The kinetics of photoisomerization and time-evolution of hybrid thin films were investigated using UV-Vis s and FTIR spectroscopies, as well as appropriate models developed with new analytical methods. The existence of azo-dye MR in the complex is crucial for the resource action of the trans cis cycles through UV-illumination Visible-illumination relaxations. The results of the UV–Vis and the FTIR investigations prove the cyclical trans cis-states. Consequently, PEO-(MR-Graphene) hybrid composite thin films can be introduced as possible applicants for photochromic molecular switches, light-gated transistors, and molecular solar thermal energy storage media.

Structural Colors by Synergistic Birefringence and Surface Plasmon Resonance.

One-dimensional nanomaterials including cellulose nanocrystals (CNCs) and gold nanorods (GNRs) are widely used in optical materials due to their respective inherent features: birefringence with accompanying light retardation and surface plasmon resonance (SPR). Herein, we successfully combine these properties of both nanorods to generate synergistic and readily tunable structural colors in hybrid composite polymer films. CNCs and GNRs are embedded either in the same or in separate films after unidirectional alignment in dynamic hydrogels. By synergistically leveraging CNCs and GNRs with diverse amounts in hybrid films or stacked separate films, wide-ranging structural colors are obtained, far beyond those from films solely with aligned CNCs or GNRs. Higher GNR contents enhance light absorption at 520 nm with promoted magenta colors, while more CNCs affect the overall phase retardation with light absorption between 400 and 700 nm between crossed polarizers. Moreover, adjusting the angles between films solely with CNCs or GNRs via a stacking/rotating technique successively manipulates colors with flexible film combinations. By rotating the films with aligned GNRs (0-180°), light absorption can traverse from ∼500 to 650 nm. Thus, tuning the adjustable synergism of birefringence of CNCs and SPR of GNRs provides great potential for structural colors, which enlightens inspirations for designing functional optical materials.

ZnS/MoS2 film grown on Mo foil as binder free electrode for supercapacitor

In this work, the design and synthesis of ZnS/MoS2 hybrid nanoparticle film directly grown on Mo foil is reported by a one-step hydrothermal reaction. The as-prepared hybrid composite film exhibits a specific capacitance of 956.3 F g−1 at 10 mA cm−2 which is about 6.4 times of the pristine MoS2 film (150 F g−1 at 10 mA cm−2), and excellent cycling stability (85.7% capacity retention after 2000 cycles). Generally, the greatly enhanced electrochemical performance is attributed to the robust nanoparticle structure on Mo foil, providing large surface, close contact between the substrate and active materials, and low inner resistance. In addition, these two kinds of active materials provide a synergistic effect for the improved capacitive property.