Preparation of PANI–PVA composite film with good conductivity and strong mechanical property

The polyaniline (PANI)–polyvinyl alcohol (PVA) conductive composite films [doped with hydrochloride (HCl), dodecylbenzene sulphonic acid and amino sulphonic acid (NH₂SO₃H) aqueous solution] were synthesised by ‘in situ’ polymerisation, and their conductivities were compared. Among these composite films, HCl–PANI–PVA composite film possessed the highest conductivity that reached 1360?S·m^??1 [w_(PVA)?=?40%]. Meanwhile, the effects of PVA content, HCl concentration, oxidant ammonium persulphate (APS) dosage, reaction time and film drying temperature on tensile strength of the HCl–PANI–PVA composite films were studied. The tensile strength of the film was improved greatly due to effective mixture of PANI and PVA. When the PVA content was 40%, C_(HCl)?=?1.0?mol·L^??1, reaction time was 4.0?h, n_(APS)/n_(aniline)?=?1.0 and film drying temperature was 80°C, and the tensile strength of the HCl–PANI–PVA composite film reached the maximum of 60.8?MPa. At the same time, the structure of composite materials was characterised and analysed through ultraviolet spectrum and SEM.     

Preparation and performance of PANI–PVA composite film doped with HCl

The polyaniline (PANI)–poly (vinyl alcohol) (PVA) composite film doped with HCl was prepared by adopting PVA as matrix. Effects of PVA content and film drying temperature on properties of HCl–PANI–PVA composite film were studied. A comparison was made for tensile strength, elasticity, conductivity and thermal stability of PVA, HCl–PANI or HCl–PANI–PVA. PVA film presented the highest tensile strength and elasticity (150.8?MPa and 300.0%), but its conductivity was the lowest. The conductivity of HCl–PANI–PVA was the highest (1500?S?m^?1), and tensile strength and elasticity of HCl–PANI–PVA were higher than those of HCl–PANI. The order of their thermal stability is PVA?>?HCl–PANI?>?HCl–PANI–PVA before 260°C, and the order of their thermal stability is HCl–PANI?>?HCl–PANI–PVA?>?PVA after 260°C. At the same time, the structure and conductive mechanism of composite materials were characterised and analysed through infrared and scanning electron microscopy (SEM).     

Characterization and antibacterial activity of PVA–PVP–CS carvacrol-loaded polymer composite films for urinary catheter

The formation of biofilm over the urinary catheter leading to CAUTI remains an unresolved major cause of bacteremia in hospital patients. In-order to find an alternative, feasible solution we developed a new potential composite film containing polyvinyl alcohol, polyvinylpyrrolidone, and chitosan by solvent evaporation technique. The developed composite film was loaded with carvacrol (CAV), a naturally occurring broad-spectrum antimicrobial agent and was characterized. The CAV-loaded film exhibited appreciable growth inhibition, resistance to biofilm formation, and microbial penetration of infectious bacterial strains isolated from hospital such as Escherichia coli, Bacillus subtilis, and Salmonella typhimurium. Thus, the developed CAV-loaded polymer composite film can serve as a potential alternative biomaterial for developing biofilm formation-resistant urinary catheter.     

Demineralized whey–gelatin composite films: Effects of composition on film formation,mechanical, and physical properties

In this study, the objective was to prepare and characterize films with different concentrations of demineralized whey (3–10%) and gelatin (1–3%) containing glycerol (10–70%) as a plasticizer and chitosan or nanochitosan as an additive. Mechanical properties, thickness, grammage, opacity, moisture content, water, and ethanol solubilities of the obtained films were determined. The formation of films without glycerol and gelatin was not possible. A higher gelatin concentration led to more desirable mechanical properties. Thickness, grammage, opacity, and moisture content remained almost constant after increasing gelatin concentration. Heightening glycerol concentrations raised water and ethanol solubility. Despite presenting high water solubility, the films showed low ethanol solubility. The formulation containing whey (3%), glycerol (20%), gelatin (3%), and chitosan (0.1%) resulted in the highest performing film concerning physical and mechanical aspects. Through Fourier transform infrared spectroscopy analysis, it was possible to observe the displacement and the frequency reduction of the band near 3,300 cm⁻¹, revealing different protein interactions. It indicates that hydrogen bonds occur between the amino group and  OH of the protein molecules reducing film hydrophilicity. Contact angle measurements also showed a less hydrophilic character. The films present the potential to prolong the shelf life of food, such as dairy products.     

退火工艺对PVA/PEDOT:PSS共混纤维性能的影响

将聚乙烯醇(PVA)的水溶液与聚3,4-乙撑二氧噻吩:聚对苯乙烯磺酸(PEDOT:PSS)水分散液共混,以甲醇作为凝固浴,通过湿法纺丝制得PVA/PEDOT:PSS共混导电纤维。通过改变湿法纺丝后处理过程中的退火工艺,探究不同的退火工艺对PVA/PEDOT:PSS共混导电纤维性能的影响。通过红外光谱分析仪、高阻计、电子单纤维强力仪和扫描电子显微镜对共混纤维的结构与性能进行测试表征。结果表明,随着退火温度的增加及退火时间的延长,PVA/PEDOT:PSS共混导电纤维的电导率均呈现出增加的趋势;单纤维拉伸强度逐渐增加,拉伸断裂伸长率逐渐减小;纤维表面粗糙度增大,沟槽数量增多。     

Electrostatic self-assembly of graphene–silver multilayer films and their transmittance and electronic conductivity

By alternating deposition of graphene oxide (GO) sheets and silver nitrate by means of an electrostatic self-assembly method, a GO–Ag⁺ film was prepared. After thermal annealing, a graphene–silver nanoparticle (GE–Ag) multilayer film, with high transparency and electrically conductivity, was obtained. The transmittance of a film with four assembly cycles was 86.3%, at a wavelength of 550 nm, better than that of a pure GE film (73.8%). While the surface resistance was 97 kΩ □^?1, much lower than that of a pure GE film (430 kΩ □^?1). The Ag nanoparticles play a crucial role in improving the properties of the GE–Ag film, acting as conductive paths and light-trapping nanoparticles, which not only reduces the reflection of the film, but also prevents the GE sheets from aggregation and provides conductive paths between sheets, improving the electrical conductivity.     

Preparation and corrosion assessment of electrodeposited Ni–SiC composite thin films

Ni–SiC composite thin films were successfully prepared via direct-current (DC) and ultrasonic pulse-current (UPC) deposition. The morphologies, mechanical properties, and corrosion properties of the films were investigated via atomic force microscopy, X-ray diffraction (XRD), Vickers hardness test, scanning electron microscope (SEM), cyclic polarization, and gravimetric analysis. The results show that the Ni–SiC composite thin films synthesized via UPC deposition possess a compact and exiguous surface morphology. The XRD results indicate that the average grain diameters of Ni and SiC in the UPC-deposited thin film are 63.6 and 38.5 nm, respectively. The maximum microhardness values for the DC- and UPC-deposited Ni–SiC composite thin films prepared are 871.7 and 924.3 HV, respectively. In the corrosion tests, the UPC-deposited films have a higher corrosion resistance than those prepared by DC deposition with the same SiC content.     

Electrophoretic deposition of functionally-graded NiO–YSZ composite films

Functionally-graded NiO–8 mol % YSZ composite films were prepared by a controlled voltage-decay electophoretic deposition (EPD) process. The films consisted of three layers with varying NiO concentrations and porosities. Effects of different parameters including the type of the organic media, solid concentration, NiO:YSZ ratio, and iodine on the stability of EPD suspensions and deposition kinetics were studied. A stable NiO–YSZ suspension was attained in isopropanol with NiO–YSZ ratio of 60:40 and iodine concentration of 0.5 mM. The composite film contained varying NiO concentration from 46 wt.% near the substrate to 32 wt.% close to the electrolyte with 42 wt% NiO in the intermediate region. The thickness of each layer is about 10, 44 and 68 μm, respectively. The prepared anode could be promising for solid oxide full cells as it compromises good contact to the electrode with higher corrosion resistance and active reaction zone with the electrolyte.     

In-situ sol–gel synthesis of zirconia networks in flexible and conductive composite films

The conductive and stretchable films with improved hardness are suitable for the fabrication of flexible electronic devices. This study describes the sol–gel technique to prepare a novel conductive and flexible film consisting of epoxidized natural rubber (ENR), doped polyaniline (PD) and zirconia. The zirconia networks were directly synthesized in-situ in ENR/PD solution and flexible conductive composite film with improved hardness was obtained. The morphology study revealed the size of PD decreased significantly from 77.89 ± 43.95 nm to 4.32 ± 1.13 nm and highest electrical conductivity of 1.9 × 10⁻³ S/cm was achieved with 10 wt.% percolation threshold of zirconia precursor. The binding energy of Zr3d_5/2 and Zr3d_3/2 decreased, suggesting that zirconia was converted to the lower oxidation state. Furthermore, the shape of PD changed from spherical to rod-like structure with root mean square value of 2 nm, while the hardness and reduced modulus improved to 1.72 MPa and 36.7 MPa, respectively.     

Electrical and conductivity performances of secondary phase in 0–3 type bismuth ferrate–based composite ceramics

The composite design strategy for ferro-piezoelectric ceramics has been successfully used to get excellent performances, whereas few studies focus on the electrochemical characteristics of the second phase in the composite. In this work, MgO, due to its high resistance insulation and high breakdown strength, was selected to be compounded with 0.7BiFeO₃–0.3BaTiO₃ (BFBT) ceramics. Intriguingly, an unreported second phase was derived from the solid-state reaction and identifying its chemical composition as about Mg₁₃Ti₃Fe₂₄O₅₅. AC impedance technique was applied to clarify the electrical contribution of the second phase in composites. The results show that it has higher resistivity at the high-temperature stage and more stable capacitance with temperature. Moreover, the second phase can improve the overall dielectric-temperature stability. Ultimately, it indicates composite strategy can bring some beneficial effects on BFBT ceramics, and this present work may provide an alternative route for separating the electrical contribution of different regions for composite ceramics.     

PEDOT:PSS导电性能优化方法的研究进展

导电高分子材料聚(3,4-乙撑二氧噻吩)-聚苯乙烯磺酸(PEDOT:PSS)因其稳定性好、电导率高、溶液加工性好等优点而受到人们的广泛关注。PEDOT:PSS的电导率经化学或物理的方法处理后会有较大改变。对提高PEDOT:PSS材料电导率的方法进行了综述,通过掺杂(有机溶剂、无机纳米粒子、酸处理)、与碳材料复合等方法可以提高PEDOT:PSS的电导率,并对其以后的发展进行了展望。     

A kinetic study of in situ polyaniline–gold composite film formation

Chloroaurate acid (HAuCl₄) was used as an oxidant and aniline (ANI) was used as a reducing agent to prepare a polyaniline–gold (PANI-Au) composite film by in situ polymerization. The formation of the composite film was monitored using a quartz crystal microbalance (QCM). The effects of the concentrations of HAuCl₄ and ANI as well as the reaction temperature on the formation of the PANI-Au composite film are discussed. The kinetics of the reaction were investigated by the QCM technique. The results indicate that the kinetics of the reaction are of order 0.5 with respect to HAuCl₄ and 1.5 with respect to aniline. The film growth rate increased with increasing ANI, HAuCl₄ concentration and reaction temperature. The activation energy calculated from the temperature dependence of the growth rate was 40.32 ± 0.15 kJ/mol. In situ UV-visible spectra of the reaction process were obtained and compared to the reaction process using the QCM technique.     

PEDOT:PSS薄膜导电性能优化的研究进展

聚（3,4-乙撑二氧噻吩）:聚苯乙烯磺酸盐（PEDOT:PSS）具有高导电性、高柔韧性、出色的稳定性、易于成膜和成本低等优点,被认为是最有价值的导电聚合物之一,它在储能转换和电子系统中有着广阔的应用前景。然而,原始的PEDOT:PSS薄膜的电导率较低（<1 S/cm）,阻碍了要求其高导电性的实际应用,于是人们提出了各种方法来提高PEDOT:PSS薄膜的电导率。本文综述了优化PEDOT:PSS薄膜电导率的新进展,并介绍了掺杂处理、后处理等提高PEDOT:PSS薄膜电导率的方法。     

Thermal conductivity of a graphene oxide–carbon nanotube hybrid/epoxy composite

Thermally conductive graphene oxide (GO)–multi-wall carbon nanotube (MWCNT)/epoxy composite materials were fabricated by epoxy wetting. The polar functionality on the GO surface allowed the permeation of the epoxy resin due to a secondary interaction between them, which allowed the fabrication of a composite containing a high concentration of this hybrid filler. The thermal transport properties of the composites were maximized at 50 wt.% of filler due to fixed pore volume fraction in filtrated GO cake. When the total amount of filler was fixed 50 wt.% while changing the amount of MWCNTs, a maximum thermal conductivity was obtained with the addition of about 0.36 wt.% of MWCNTs in the filler. Measured thermal conductivity was higher than the predicted value based on the by Maxwell–Garnett (M–G) approximation and decreased for MWCNT concentrations above 0.4%. The increased thermal conductivity was due to the formation of 3-D heat conduction paths by the addition of MWCNTs. Too high a MWCNT concentration led to increased phonon scattering, which in turn led to decreased thermal conductivity. The measured storage modulus was higher than that of the solvent mixed composite because of the insufficient interface between the large amount of filler and the epoxy.     

Graphene oxide–polyoctahedral silsesquioxane–chitosan composite films with improved mechanical and water-vapor-transport properties

Graphene oxide (GO) and ball-milled maleamic acid–isobutyl polyoctahedral silsesquioxanes (MAIPSs) were incorporated simultaneously into chitosan (CS) via solution blending to evaluate their combined effects on the structures and properties of composite films. GO and MAIPS aggregates were homogeneously dispersed in CS and affected the crystallinities of the composite films. The binary addition of GO and MAIPS resulted in synergistic enhancements of the tensile strength and elongation at break of the composite films. Composite films containing 3% w/w MAIPS and 0.25% w/w GO (CS–GO–MAIPS-3) exhibited the highest strength and modulus, which were 48 and 42.2% higher, respectively, than the values of the CS film. The water-vapor-sorption isotherms revealed that monolayer sorption sites decreased with the addition of GO or/and MAIPS, but the dissolution process was not significantly influenced. The water-vapor permeability reached its lowest value for the CS–GO–MAIPS-3 film because of hindered diffusion with the presence of impermeable nanoparticles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47748.     

Rapid synthesis of high strength cellulose–poly(vinyl alcohol) (PVA) biocompatible composite films via microwave crosslinking

The present study describes microwave (MW)-assisted rapid synthesis of biocompatible poly(vinyl alcohol) (PVA) composite films that demonstrate synergy between reinforcement and crosslinking. Bacterial cellulose (5% w/w) nanowhiskers (reinforcement) and tartaric acid 35% (w/w) (crosslinker) are incorporated in PVA to prepare crosslinked cellulose–PVA composite films. The properties of thus prepared crosslinked cellulose–PVA composite films are compared with samples crosslinked with conventional hot air oven heating (CH). Crosslinking by both of the methods reduces water absorption of PVA by around an order of magnitude and improves its thermal stability. An increase in strength from 42 (PVA) to 172 MPa and 159 MPa for MW and CH crosslinked samples, respectively is also observed. Although composites prepared using MW and CH show similar properties, MW takes only 14 min compared to 2 h in case of CH. Notably, the prepared composites demonstrate hemocompatibility and cytocompatibility, and may also be explored for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47393.     

Synthesis and characterization of polyaniline–titanium(IV)phosphate cation exchange composite: Methanol sensor and isothermal stability in terms of DC electrical conductivity

Electrically conductive composite of polyaniline–titanium(IV)phosphate (PANI–TiP) was synthesized by sol–gel method. The obtained composite was characterized by using Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The composite showed good ion-exchange capacity and isothermal stability in terms of DC electrical conductivity retention at an ambient conditions below 100 °C. The composite material was investigated as alcohol vapors sensor and compared with blank polyaniline. The results showed that the composite was more selective and sensitive towards methanol vapors.     

PEDOT:PSS对电极的制备及其光电性能研究

通过DMSO掺杂处理和硫酸后处理两种方法制备了基于聚3,4-亚乙二氧基噻吩∶聚苯乙烯磺酸盐(PEDOT:PSS)的对电极。采用循环伏安(CV)和电化学阻抗谱(EIS)研究了PEDOT:PSS电极的电化学性质,发现与DMSO处理PEDOT:PSS电极相比,经过硫酸处理的PEDOT:PSS电极对于I3-到I-还原反应具有更高的电催化活性和更小的电荷转移电阻。由纯的和改性PEDOT:PSS对电极分别组装了染料敏化太阳能电池(DSSCs),并研究了其光伏性能。结果表明基于硫酸处理的PEDOT:PSS电极的电池在上述三种类型电池中具有最高的光电转换效率(2. 11%)。     

Facile synthesis of MgO–Mg2SiO4 composite ceramics with high strength and low thermal conductivity

The recycling of solid waste is a win-win solution for humans and nature. For this purpose, magnesite tailings and silicon kerf waste were employed to prepare MgO–Mg₂SiO₄ composite ceramics by solid-state reaction synthesis in the present work. Then, effects of sintering temperature and raw material ratio on as-prepared ceramics were systematically studied. As-prepared ceramics showed improvement in their relative density (from 47.55%–68.12% to 90.96%–95.25%) and cold compressive strength (from 7.34–118.66 MPa to 303.39–546.65 MPa) with the increase in sintering temperature from 1300 to 1600 °C. In addition, it was found that Si promoted synthesis process of Mg₂SiO₄ phase through transient liquid phase sintering and Fe₂O₃ accelerated sintering process through activation sintering. Consequently, the presence of Mg₂SiO₄ phase effectively improved the density and strength of MgO–Mg₂SiO₄ composite ceramic, while reducing its thermal conductivity. This work provides a potential reutilization strategy for magnesite tailings, and as-prepared products are expected to be applied in fields of construction, metallurgy, and chemical industry.     

Electrodeposition and dissolution of Co–W alloy films

Cyclic voltammetric studies were carried out on platinum in alkaline solution containing cobalt sulphate, sodium tungstate, dimethyl sulphoxide and triammonium citrate. Spectral u.v. absorption studies of cobalt citrate complex indicate the species to be [Co L (H₂O)₃]²⁺, where L is triammonium citrate. The deposition of cobalt involves a stepwise electron transfer mechanism. The observed cyclic voltammetric data show that the alloy deposition is possibly from cobalt–tungstate complex. The citrate ions and dimethyl sulphoxide hinder the alloy deposition. Dimethyl sulphoxide, which specifically adsorbs on the electrode surface, favours the hydrogen evolution reaction (HER), whereas tungstate hinders the HER. Stripping voltammograms show the existence of cobalt rich alloy phases. X-ray diffraction studies further confirm the phases to be Co₃W and Co₇W.