Hybrid Composite Films Research Articles

The Design and Preparation of Transparent Hybrid Composite Thin Films with Excellent Optical Properties and Improved Thermal Insulation by Optimized Combination of Nanomaterials

For a single nano-optical material, it is difficult to possess high transmittance and adequately filter ultraviolet (UV) and infrared radiation (IR) simultaneously. Consequently, hybrid nano-optical materials comprising components of appropriate proportions for superimposing serviceable optical property are required. The design, optimization and processing of new composite blends with an aim to creating defect free thin films is far from a trivial endeavor. In this report, optimum composition and optical properties of hybrid nano-optical material has been determined and improved by crossover matching experiments and ball milling, respectively. Film preparation has been optimized to reduce defects expressed as cracks, tiny bubbles, strips, groove points, corrugation, and formation of acicular fibers by regulating proportion of polyvinyl butyral colloid and dry film processes. Two ameliorative processing conditions are exemplified where the resultant composite films possessed 86% maximum transmittance in the visible range and 90% and 50% blocking rate with respect to the IR and UV bands.

Physical, mechanical, optical and biodegradability properties of polyvinyl alcohol/cellulose nanofibrils/kaolinite clay-based hybrid composite films

ABSTRACT The aim of this study was to investigate the physical, mechanical, optical and biodegradation properties of polyvinyl alcohol (PVA)/cellulose nanofibrils (CNFs)/Kaolinite clay (KC)-based hybrid composite films prepared by the solution casting method. CNFs were extracted from barley husk using the acid hydrolysis method. The average diameter of the CNFs was 17.5 nm and the length was more than 1100 nm. Water uptake of the composite films increased with the increase in the amount of CNFs in PVA matrix from 5% to 25%. While a significant reduction in water uptake was observed for KC-reinforced films, the optical transmittance changed a little with the addition of CNFs and a transmittance of 90% was observed for the film containing 5% CNFs. Tensile strength of the hybrid film containing 5% CNFs and 5% KC increased by 62% as compared to that of the PVA film. Soil burial test revealed that the PVA/CNF composite films exhibited high weight loss (%) in comparison with PVA/KC and PVA/KC/CNF composite films. The film containing 25% CNFs showed the highest weight loss of 46.54% after 75 days of burial in soil.

Functionalized Multi-Walled Carbon Nanotubes and Micro Cellulose Reinforced Poly (Vinyl Alcohol) Hybrid Composite Films: Characterization and Reprocessing Performance

The aim of this research paper was to investigate the synergetic effect of micro cellulose and multi-walled carbon nanotubes (MWCNTs) combination on physicochemical, mechanical and reprocessing performance of Poly (Vinyl Alcohol) hybrid composite films. The hybrid composite films production was carried out by the solution casting method, and the reprocessed films were produced using defective (torn, faulty) films from primary production by the same method. The combined use of MWCNTs and micro cellulose improved the hydrophobicity approximately 85% in ratio. After the reprocessing, decreased intensities of the peaks in the FTIR and Raman results confirmed the reduced molecular interaction between all components of the hybrid composite film, moreover, SEM and TEM revealed the negative defects such as agglomeration which caused mechanical strength decrease. The tensile strength of PVA hybrid composite films loaded cellulose/MWCNTs, reached 97 MPa strength value and elongation at break decreased to 33% according to the neat PVA film. The study results revealed that hybridization had a remarkable impact on improving characteristic properties of composite films and reprocessing process might have been compatible with solution casting method.

Preparation and characterization of cornhusk/sugar palm fiber reinforced Cornstarch-based hybrid composites

In the current study, a series of hybrid composite films were prepared from cornhusk fiber (CHF) and sugar palm fiber (SPF) through a solution casting technique, using cornstarch (CS) as matrix and fructose as a plasticizer. SPF at 2%, 4%, 6%, and 8% (w/w dry starch) concentrations was loaded into CS/CH composites with 8% CHF and 25% fructose. The physical, morphological, thermal, tensile, and barrier characteristics of the final product were evaluated. From the findings, there was a marked decrease in density, moisture content, solubility, and water absorption of the hybrid films. SEM images exhibited a strong interfacial interaction and good biocompatibility between polymer matrix and reinforcement fiber, which reflected on the enhanced tensile strength and Young’s modulus as well as the relative crystallinity. The thermostability of hybrid films has also been enhanced, as indicated by the increased onset degradation temperature. Fourier transform infrared analysis revealed an increase in intermolecular hydrogen bonding following fiber loading. As well as the water barrier assessment showed greater resistance to vapor transmission, evidenced by the lower water vapor permeability rate following SPF loading. To sum up, the hybridization of CS/CH composites with SPF, in general, has improved the performance of the biocomposites for biomaterials applications, especially for 6% of SPF loading.

MXene Quantum Dot/Polymer Hybrid Structures with Tunable Electrical Conductance and Resistive Switching for Nonvolatile Memory Devices

AbstractLow‐dimensional MXene materials including MXene quantum dots (MQDs) and nanosheets have attracted extensive attention owing to their unique structures and novel properties, but their most attractive features are still less explored than expected. A systematic study of the memory effects of MQD‐based electronics is reported. Monodisperse MQDs are prepared by using a one‐step facile hydrothermal synthetic method. By varying the MQD content in polyvinylpyrrolidone (PVP) hybrid composite films, the electrical conductance of an indium tin oxide (ITO)/MQD‐PVP/gold (Au) sandwich structure can be tuned precisely from insulator behavior to irreversible resistive switching, reversible resistive switching, and conductor behavior. These irreversible and reversible resistive switches are capable of exhibiting write‐once‐read‐many times (WORM) and flash memory effects, respectively. Both types of devices operate stably under retention testing, with a high on/off current ratio up to 100. The tunable memory and transient features of these hybrid films are likely due to MQD charge trapping due to their quantum confinement and dissolvability of memristive components. The results suggest that MXene nanomaterials are promising as resistive switching trigger for emerging nonvolatile memories for data storage, specially data storage security.

Layer-by-Layer nanostructured films of magnetite nanoparticles and polypyrrole towards synergistic effect on methylparaben electrochemical detection

The sustained use of cosmetics, hygiene products and medicines containing methylparaben (MeP) can be related to cases of cancer in women and children, which is why it is important to develop simple ways to monitor this compound. Gold electrodes were modified with Layer-by-Layer (LbL) films of magnetite nanoparticles (MNP) and polypyrrole (Ppy) for electrochemical determination of MeP. To investigate the synergistic effect between the MNP and Ppy, three different LbL architectures were tested: multilayers of Ppy with an conventional polycation poly(allylamine hydrochloride) – Au/(PAH/Ppy)3, MNP with a conventional polyanion poly(vinyl sulfonic acid) – Au/(MNP/PVS)3 and the hybrid composite film Au/(MNP/Ppy)3. The highest oxidation current and lowest oxidation potential were achieved by the Au/(MNP/Ppy)3 electrode in a range up to 131.4 μmol L−1 with a limit of detection of 9.95 × 10−8 mol L−1. The performance of the electrochemical sensor was statistically investigated by the Miller-Miller method demonstrating accuracy comparable to an analytical method (capillary electrophoresis). MeP was determined in urine, breast milk and cosmetic with recovery values varying from 84.0% to 113.3%.

Over 1000‐Fold Enhancement of the Unidirectional Photoluminescence from a Microsphere‐Cavity‐Array‐Capped QD/PDMS Composite Film for Flexible Lighting and Displays

AbstractThe development of quantum dot (QD) composite films for lighting and displays is of great importance because of their exceptional mechanical flexibility, chemical stability, and optical tunability. Generally, QDs are attached to plasmonic nanostructures to enhance their photoluminescence (PL) emission. However, plasmonic QD composite films suffer from deteriorated inherent quantum yields and lower enhancement ratios due to variations in the refractive index and dielectricity in the composites. Herein, the use of a dielectric microsphere cavity is reported to realize over 1000‐fold enhancement of the PL in CdSe/ZnS QD/polydimethylsiloxane films with a highly unidirectional emission angle of ≈9°. The field regulation by the optical whispering‐gallery resonance and directional antenna effect at the microscale is revealed to interpret the PL enhancement mechanism. Additionally, the microsphere cavity allows for the enhancement of white‐light emission in the RGB‐QD hybrid composite film. The present work inspires a straightforward strategy for boosting the light efficiency in QD composite films, with promising applications in flexible lighting/display devices.

Impact of reinforcing additives on the structure and performance of composite films based on regenerated cellulose from corn stalk pith

Cellulose was extracted from corn stalk pith (CSP) and used for fabricating hybrid composite films with acceptable physical properties. As reinforced additives, low contents of graphene oxide (GO) and black phosphorene (BP), both ranging from 0.05 to 0.15 wt%, were separately incorporated into the cellulose matrix in a ZnCl2 aqueous system. A series of the composites were prepared via a regeneration process. The as-prepared composites showed various properties depending largely on the additive content, manner of processing, and the type of additive used. GO and BP nanosheets were homogeneously dispersed in the regenerated cellulose (RC), smoothly forming the dense films. Crystalline structures of RC-based films were revealed to be cellulose-II, and in addition to GO-crosslinked RC samples (RC-GO), an increase in the additive dosage led to a decrement in the crystallinity index of blended films (RC/GO and RC/BP). At 0.15 wt% additive amount, the RC-GO possessed superior thermal stability, tensile strength, and Young’s modulus, increasing 7.8%, 190.2%, and 79.0%, respectively, while the RC/BP exhibited a 3.5 times improvement in the elongation at break.

Preparation and Characterization of Hybrid Composite Film Based on Synthetic and Natural Materials

Low density polyethylene / tapioca starch (LDPE/TS) blends have respectable biodegradation properties and poor mechanical and thermal properties compared to neat LDPE film. The focal target of this study is to investigate the effect of calcium carbonate (CaCO3) loading on mechanical, thermal, and biodegradation properties of LDPE/TS film. LDPE/TS/CaCO3 blend films were prepared using film blown processing. The results indicated that the maximum loading of CaCO3 which feasible to be incorporated into (45:20) LDPE/TS blend is 10% without exertions during film processing. CaCO3 has remarkable effect on mechanical properties of LDPE/TS films in both machine direction (MD) and cross direction (CD). Water absorption capacities of the films were reduced after the addition of CaCO3. Differential scanning analysis shows that more amorphous regions were generated in the blend structure after the addition of CaCO3 into the blend. Scanning Electron Microscope (SEM) analysis indicated a significant distribution of starch and CaCO3 particle in LDPE matrix, wherever the size of starch particles seems to be bigger than the size of CaCO3 particle.

Electrical properties of stretchable and skin–mountable PDMS/MWCNT hybrid composite films for flexible strain sensors

Flexible strain sensors based on carbon nanofillers have great potential in the application of skin-adhesive sensors, wearable sensors, and tactile sensors, due to their superior electrical properties. Herein, the electrical properties of highly sensitive PDMS/MWCNT strain sensors made by vacuum filtration method were investigated. In order to obtain the electrical percolation curve of the flexible conductive films, first different samples were made with the same surface area but with different wt. % of CNTs. Then, depending on CNT content, the obtained conductive films exhibited initial electrical resistance in the range of 12.5 KΩ to 22.8 MΩ. The piezoresistive films with the CNT concentration of 1.4 to 2.9 [Formula: see text] had shown superior resistance drop, so this interval was determined as the percolation threshold region. According to the SEM images, the nanocomposite layer thickness of the flexible strain sensors in this region was 790 nm to 1210 nm. Afterward, the percolation curve was obtained using curve fitting to the experimental data and the exact value of the percolation threshold was defined as [Formula: see text]. Finally, in order to determine the minimum gauge factor ([Formula: see text]) of the sensors in percolation region, a flexible strain sensor in the upper limit of this region was selected and the piezoresistive properties of the selected sample were investigated.

Direct electrochemistry of glucose oxidase based on one step electrodeposition of reduced graphene oxide incorporating polymerized l-lysine and its application in glucose sensing.

The direct electron transfer and enzyme catalytic activity were investigated in electrochemical biosensor based on glucose oxidase (GOx) and electrochemical reduced graphene oxide-poly-(l-lysine) (ERGO-PLL) hybrid composite film embedded in a biocompatible matrix of Nafion. The ERGO-PLL was fabricated onto glassy carbon electrode (GCE) through one step electrodeposition of RGO incorporating PLL from graphene oxide-l-lysine aqueous dispersion. The fabrication process of Nafion/GOx/ERGO-PLL/GCE has been characterized by cyclic voltammetry and electrochemical impedance spectroscopy, and the surface morphology of modified electrodes were characterized by scanning electron microscopy. A pair of well-defined redox peaks with formal potential and peak separation of -0.461 V and 30 mV were observed at scan rate of 50 mV s-1, the electron transfer rate constant was calculated to be 18.7 s-1, demonstrated that direct electron transfer between immobilized GOx with ERGO-PLL and GCE was achieved. Moreover, the fabricated enzyme biosensor exhibited excellent electrocatalytic activity for determination of glucose in O2-free PBS (7.40) with linear voltammetric response from 0.005 to 9.0 mmol L-1, and detection limits (S/N = 3) of 2.0 μmol L-1. This work indicates that ERGO-PLL based modified electrode is superior to that of graphene based, and could be applied in biosensors, bioelectronics and electrocatalysis, etc.

Preparation of a glassy carbon electrode modified with reduced graphene oxide and overoxidized electropolymerized polypyrrole, and its application to the determination of dopamine in the presence of ascorbic acid and uric acid.

This paper presents a method for the preparation of a graphene-based hybrid composite film by electrodeposition of reduced graphene oxide and overoxidized electropolymerized polypyrrole onto a glassy carbon electrode (GCE) using cyclic voltammetry. The morphology of the hybrid composite film was characterized by scanning electron microscopy. The electrochemical activity of the modified GCE was studied by cyclic voltammetry using the negatively charged redox probe Fe(CN)63- and the positively charged redox probe Ru(NH3)63+. The modified GCE displays excellent electrocatalytic activity for dopamine (DA) and uric acid (UA), but electrostatically repulses ascorbate anion under physiological pH conditions. The voltammetric response to DA is linear in the 2.0μM to 160μM concentration range even in the presence of 1.0mM ascorbic acid and 0.1mM of UA. The detection limit is 0.5μM. The amperometric response to DA (best measured at 0.22V vs. Ag/AgCl) extends from 0.4μM to 517μM and has a 0.2μM detection limit. Graphical abstract Schematic presentation of the fabrication of a glassy carbon electrode modified with reduced graphene oxide and overoxidized electropolymerized polypyrrole, and its application to the determination of dopamine in the presence of ascorbic acid and uric acid.

Synthesis of P3HT base semiconducting hybrid films and their photocatalytic properties

Regioregular poly(3-hexylthiophene) (rr-P3HT) was employed as the supporting polymeric matrix to generate hybrid composite films by mixing with natural zeolites, ZnO, and TiO2. Several P3HT-based hybrid composite films were deposited by a convenient method, characterized, and applied to the photocatalytic degradation of rhodamine 6G (R6G). The photocatalytic activity of the hybrid composite films was analyzed by degradation of R6G solutions (blank) under UV radiation (365 nm) and sunlight. It was observed that the photocatalytic activity of the composite films was higher as compared to the neat films of P3HT. This behavior was attributed to the extended photoresponse of the coupled organic–inorganic semiconductor system, facilitating separation of photogenerated carriers due to the strong interfacial interaction. The highest proportion of decolorization ratio of R6G obtained was close to 100%, and it was observed for the composite films P3HT/TiO2/ZnO and P3HT/chabazite/TiO2/ZnO under UV irradiation. Under sunlight, 99% and 97% decolorization ratios were obtained for P3HT/TiO2 and P3HT/TiO2/ZnO composite films, respectively.

Preparing carbon black/graphene/PVDF-HFP hybrid composite films of high piezoelectricity for energy harvesting technology

Poly(vinylidene fluoride) (PVDF) and its copolymers with high piezoelectricity are of great interest for high efficient energy harvesting devices. In this study, carbon black (CB) and few-layer graphene (FLG) were added into one kind of copolymers of PVDF, i.e., poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to fabricate hybrid composite films by the solution casting method. By adjusting the contents of CB and FLG, the relative fraction of β-phase increased dramatically, leading to a high piezoelectricity of the hybrid composite films. The maximum output voltage and the harvesting power density of the CB/FLG/PVDF-HFP films was 181% and 329% of the pristine PVDF-HFP films, respectively. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy analysis (FT-IR) and differential scanning calorimetry (DSC) were used to investigate the effect of hybrid fillers on the crystallization, mechanical stretching and poling process. Mechanical properties of the composite films were also measured. The dramatically enhanced piezoelectricity shows the great potential in energy harvesting devices.

Enhanced thermoelectric performance of P-type Sb2Te3 thin films through organic-inorganic hybridization on flexible substrate

In this work, a new idea of organic-inorganic hybridization was proposed to fabricate flexible p-type - Sb2Te3/CH3NH3I thin films. The CH3NH3I has a strong adsorption which can promote the growth of organic molecules, improve the crystallization, and finally increase electrical conductivity. Post-annealing of the fabricated films increased the phonon scattering, thus resulting in a reduction of thermal conductivity and an increased ZT value. The annealed hybrid-composite film showed a significant enhancement in thermoelectric performance, with a maximum ZT value of 0.94 at a temperature of 413 K, which is twice as large as that of the as-deposited film.

Room-temperature solution-processed, ZrOx-based hybrid gate dielectrics for low-voltage organic thin-film transistors on plastic substrates

For advanced electronic device applications including printable, flexible organic electronics and bioelectronics, it is crucial to develop novel dielectric materials with high dielectric strength and low-temperature processability compatible with plastic substrates for producing flexible and low-voltage organic thin-film transistors (OTFTs). Herein, we report the facile fabrication of rationally designed, high-capacitance hybrid gate dielectric films for low-voltage OTFTs on plastic substrates via a room-temperature solution process. To create room-temperature-processed gate dielectrics with high dielectric strength, we designed organic-inorganic hybrid gate dielectric films by including ZrOx networks as inorganic high-k oxide materials for obtaining large capacitance and 1,6-hexanediol diacrylate as a bifunctional UV cross-linking agent and a flexible organic component for increasing the density and flexibility of films and ensuring room-temperature processability. The UV cross-linked ZrOx-based hybrid composite films with a 15 nm thickness showed excellent dielectric properties with a leakage current density of ∼10−6 A/cm2 and a capacitance of 640 nF/cm2. The film surfaces were modified with hydrophobic self-assembled monolayers to match the surface energy of organic semiconductors for enhancing the OTFT performance. The utility of the hybrid dielectrics for flexible OTFTs was demonstrated by realizing pentacene TFTs on plastic substrates with a low operating voltage at –2.5 V, a high on/off current ratio of 105, a threshold voltage as low as –0.7 V, and a hole mobility up to 0.47 cm2 V−1 s−1, which are comparable to those performed on Si substrates.

Synthesis, characterization, and adsorption properties of m-aramid and chitosan hybrid composite films with the ratio of 100/0, 85/15, 65/35, 50/50, and 35/65 toward Hg(II) ions

Synthesis, characterization, and adsorption properties of m-aramid and chitosan hybrid composite films with the ratio of 100/0, 85/15, 65/35, 50/50, and 35/65 toward Hg(II) ions

High‐performance thermoplastic hybrid composite reinforced with bucky paper for electromagnetic interference shielding

Multiwalled carbon nanotubes (MWCNTs) have extraordinary electrical conductivity but limited applications due to the ease of agglomeration, especially in thermoplastic composite. With the aim of achieving high electromagnetic interference shielding performance by applying MWCNTs in thermoplastic matrix, MWCNTs were made into buckypaper (BP) and then hot pressed with PP/PLA/TiO2 hybrid films, forming sandwich‐structured BP/PP‐PLA‐TiO2 hybrid composite films. BP was examined in terms of morphology, cell structure, and electrical conductivity, while BP/PP‐PLA‐TiO2 hybrid composite film was tested for electromagnetic shielding effectiveness (EMSE), thermal properties and UV‐cut efficacy. It was found that using vacuum filtration successfully produced BP with a smooth and sleek surface and an even porosity ranging between 20 and 45 nm. The electrical conductivity of BP was proportional to its thickness. About 90 μm‐thick BP had 75.62% lower surface resistivity and 36.63% higher electrical conductivity than 30 μm‐thick BP. Moreover, the EMSE of BP/PP‐PLA‐TiO2 composite film increased as a result of the higher thickness of BP. When the thickness of BPs was 90 μm, the BP/PP‐PLA‐TiO2 composite film had an average EMSE of 40 dB at 0–3 GHz and a peak of 70 dB, and 119% higher tensile strength and 11% higher elastic modulus than those of PP/PLA/TiO2 composite film. BP/PP‐PLA‐TiO2 composite film had UV‐cut efficacy that was close to 0%. The addition of BP was proven to improve the crystallization and thermal stability. POLYM. COMPOS., 40:3065–3074, 2019. © 2018 Society of Plastics Engineers

In-situ synthesis of flexible hybrid composite films for improved thermoelectric performance

Thermoelectric (TE) materials and devices, which enable direct conversion of thermal energy into electricity and vice versa, are a favorable technology for waste heat recovery and flexible energy generators and coolers. Here, we report the enhanced thermoelectric properties of flexible hybrid films composed of carbon nanotubes (CNTs) with good electrical and mechanical properties and inorganic nanowires with high Seebeck coefficient synthesized through an in-situ facile solution method. A two-step interface engineering process is applied to the flexible composite aiming to enhance thermoelectric properties: (1) Bi2Te3 nanowires are grown from the surface of uniformly dispersed CNTs by in-situ synthesis, and (2) a mechanical pressing and a post heat-treatment were employed to form tight interface bonding and adjust the nanowires close to stoichiometric composition. Impressively, the CNTs/Bi2Te3 nanowires composite films exhibited a peak TE power factor of approximately 0.74 mW m−1K−2 at room temperature along with admirable flexibility. The Seebeck coefficient and electrical conductivity were improved by a factor of 30 and 2.2, respectively, through mechanical pressing and post-annealing. This increase is attributed to the phase homogenization of inorganic nanowires to its stoichiometric phase and electron filtering effects due to enhanced interfaces both qualitatively and quantitatively. The flexibility and retention of the conductivity were evaluated via two different methods. This composite with high TE performance will be utilized to create flexible thermoelectric devices for energy harvesting. In addition, the findings from this study can be applied to other flexible thermoelectric materials systems to enhance thermoelectric properties.

Hybrid Conducting Composite Films Based on Polypyrrole and Poly(2‐(diethylamino)ethyl methacrylate) Hydrogel Nanoparticles for Electrochemically Controlled Drug Delivery

AbstractA 3D conductive hybrid film is fabricated based on poly 2‐(diethylamino) ethyl methacrylate (PDEA) nanoparticles with polypyrrole (PPy) as the conductive component. PDEA nanoparticles are deposited on a gold substrate by drop casting. Then, PPy is electrochemically grown through the hydrogel nanoparticles as a semi‐interpenetrating polymer network. PDEA hydrogel nanoparticles reversibly swell at low pH while PPy liberates H+ in the oxidized state. The oxidation of PPy is used to create an electrostimulated decrease in pH in the PDEA/PPy hybrid film that results in film swelling. The electrochemical properties of the hybrid conductive composite film are studied through cyclic voltammetry and electrochemical impedance spectroscopy. Doxorubicin (Dox) as model drug is encapsulated in the PDEA/PPy hybrid composite film by a pH switch. Drug electroliberation is investigated at different applied potentials from −0.65 to +0.65 V. The amount of Dox released shows a dependence on the applied potential and the duration of the electrical stimuli. The (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) tetrazolium reduction assay is conducted to evaluate the impact of the electrocontrolled release of Dox on the proliferation of the A549 cell line, showing a decrease in cell viability, proportional to the applied potential and its duration.