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.     

PANI/PPY blend thin films electrodeposited for use in EGFET sensors

Galvanostatic electrodeposited thin films of polyaniline (PANI)/polypyrrole (PPY) blend were tested as chemical sensors and evaluated according to the relative monomer concentration in polymerization solution aiming to obtain a reliable reference field‐effect transistor able to be used as contrast sensing film. The blend material presented properties that can be controlled by the polymerization process. The films were produced using aniline (0.25 M) and pyrrole (0.25 M) mixed in five different proportions (90/10, 70/30, 50/50, 30/70, 10/90) with HCl (1.0 M) in an aqueous solution. The current density was 1 mA/cm² for 300 s. The films were analyzed by their chronopotentiometric curves, thickness, reflectance spectroscopy, optical color parameters, and surface morphology. The characteristics and properties analyzed were correlated to the relative monomer concentration in the polymerization solution. The polymerization of PANI is favorable in aqueous acid solution compared to PPY, which resulted in thin films with properties varying from PANI down to PPY. The blend films presented controllable sensitivity when applied as sensing stage in field‐effect transistor devices as function of the relative monomer concentration. The sensitivity varied from 57 ± 1 mV/pH for the PANI sample, down to 25 ± 1 mV/pH for the PPY sample, presenting an exponential behavior. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46625.     

酸掺杂聚苯胺催化马来酸丁酯化及动力学

用对甲苯磺酸作为搀杂剂对水相氧化法合成的盐酸搀杂的聚苯胺(HC l/PANI)进行搀杂,制备了由聚苯胺(PANI)负载对甲苯磺酸的固体酸催化剂(PTSA/PANI)。以PTSA/PANI为催化剂、马来酸酐和正丁醇为原料合成马来酸二丁酯。考察了原料配比、催化剂用量和反应时间等因素对反应的影响以及催化剂的重复使用性能,测定了反应动力学。最佳反应工艺条件为:n(正丁醇)∶n(马来酸酐)=3.33∶1、w(PTSA/PANI)=3.81%、反应温度≤130℃、反应时间3 h。结果表明,在该条件下马来酸酐的转化率为96.23%;催化剂经重复使用5次后,马来酸酐的转化率为90.82%;确定反应级数为二级,表观活化能为41.0 kJ/mol。对甲苯磺酸搀杂聚苯胺催化剂具有催化活性高、稳定性好、容易制备、无环境污染等优点。     

Comparison of the growth process and electrochemical properties of polyaniline films prepared by pulse potentiostatic and potentiostatic method on titanium electrode

Polyaniline (PANI) films were deposited on titanium (Ti) electrode in a bath containing 0.3 mol L^?1 aniline and 1 mol L^?1 HNO₃ by pulse potentiostatic method (PPM) and potentiostatic method (PM). The chronoamperograms during aniline polymerization were recorded, and the morphologies of PANI films prepared with different polymerization periods were examined under scanning electron microscope. The difference between the processes of PANI films growth was studied. The growth processes of PANI films prepared by PPM and PM are divided into two stages. For both PPM and PM, the first stage corresponds to the formation of a compact granular PANI layer on the surface of Ti electrode. The second stage corresponds to further growth of PANI film on the surface of the compact granular PANI film. However, the PANI films prepared by PPM and PM show different morphologies in this stage. In addition, the electrochemical properties of the PANI films prepared by PPM and PM are obviously different. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 458–463, 2007     

Effects of FeCl3/ammonium persulfate composite oxidant and magnetic field on film growth rate of polyaniline doped with dodecylbenzenesulfonic acid

Polyaniline (PANI) doped with dodecylbenzenesulfonic acid (DBSA) was synthesized by emulsion polymerization using FeCl₃/ammonium persulfate (APS) as composite oxidant. The effects of different magnetic field (MF) intensities, the molar ratios of FeCl₃/APS, and the concentrations of DBSA on the film growth rate of PANI were analyzed by using a quartz crystal microbalance (QCM) technique. The film growth rate of PANI increased with increasing MF intensity and the concentration of DBSA. However, the film growth rate of PANI decreased with increasing molar ratio of FeCl₃/APS. The polymerization conditions were optimized tentatively by cyclic voltammetry (CV) testing. The peak currents and conductivity were the largest for PANI prepared under the following conditions: MF intensity 0.4 T, molar ratio of FeCl₃/APS 2:1, and concentration of DBSA 0.05 mol/L. The UV–Vis spectra of the PANI polymerization showed that the absorption intensity of PANI polymerized in the presence of MF was greater than that of PANI polymerized in the absence of MF, at the same reaction time.     

Polyaniline synthesis catalysed by glucose oxidase

A novel method for synthesis of polyaniline (PANI) in aqueous media based on application of oxidizing-enzyme glucose oxidase (GOx) is reported. Hydrogen peroxide was produced during catalytic reaction of oxidizing-enzyme glucose oxidase from Penicillium vitale and initiated the polymerization of aniline. The increase in optical absorbance in the range of 340-700 nm was exploited for the monitoring of PANI polymerization process. The role of GOx in the formation of PANI, influence of the initial concentrations of GOx, and glucose and aniline monomer on the aniline polymerization rate was studied. The study of pH influence on polymerization rate showed that PANI polymerization was occurring in a broad pH range from the pH 2.0 to 9.0. Optimal polymerization/oligomerization temperature was found to be at 37 °C, which is also optimal for GOx-catalysed enzymatic reaction. After 10 days of continuous GOx-catalysed polymerization PANI appeared as colloid-microparticles visible by an optical microscope.     

Bio- and bioelectro-catalytic properties of polyaniline/poly(acrylic acid) composite films bearing covalently-immobilized acid phosphatase

Conducting films composed of polyaniline (PANI) and poly(acrylic acid) (PAA) were prepared by electrochemical polymerization of aniline in the presence of various concentrations of PAA. The content of PAA moiety on the surface of the composite films (PANI/PAA films) was estimated by determination of carboxyl groups and found to be controlled by the concentration of PAA in polymerization solution. Acid phosphatase (ACP) was immobilized covalently on the PANI/PAA films by the condensation reaction with the carboxyl groups on the films. It was confirmed that the enzyme activity of the ACP-immobilized PANI/PAA film increased with increasing content of PAA moiety on the surface of the film, accompanying an increase in the amount of the immobilized ACP. The activity of the covalently immobilized ACP was significantly higher than that of the ACP adsorbed on the PANI/PAA film. By use of the ACP-immobilized PANI/PAA film as an enzyme electrode, bioelectrocatalytic oxidation of L-ascorbic acid 2-phosphate (ASA2P) was examined. The enzyme electrode gave the current due to the oxidation of ASA2P in proportion to the content of PAA moiety on the surface of the PANI/PAA film used, which was relevant to the activity of the covalently immobilized ACP.     

A facile method for synthesis of polyaniline nanospheres and effect of doping on their electrical conductivity

The synthesis of polyaniline (PANI) nanospheres by a simple template-free method has been described. The polymerization of aniline in aqueous medium was accomplished using ammonium persulfate without any protonic acid. The UV-vis spectrum of PANI nanospheres displayed the characteristic absorption peak of π-π* transition of the benzenoid ring at 355 nm. The oxidation state of PANI nanospheres was identified with FT-IR spectroscopy by comparing the two bands at 1582 (ring stretching in quinoid unit) and 1498 cm(-1) (ring stretching in bezenoid unit). The X-ray diffraction patterns demonstrated the low crystalline nature of PANI nanospheres. The morphology of PANI nanospheres was spherical and the mean diameter of nanospheres was found in the range of 3-12 nm. The thermal behavior of PANI nanospheres was studied by thermogravimetric analysis. The effect of doping of HCl and H(2)SO(4) on PANI nanospheres was studied by measuring the current as a function of time of exposure. The high electrical conductivity of 6×10(-2) S cm(-1) was obtained for PANI nanospheres at their optimum doping state by 100 ppm HCl.     

Quartz crystal microbalance study for chemical synthesis of polypyrrole

The quartz crystal microbalance was used to monitor the deposition of a smooth film of the conductive polypyrrole (PP) using a purely chemical method. The film was grown from the oxidative polymerization of pyrrole with potassium persulfate in aqueous solution. A comparison was made between the growth rate of PP films and the PP formed in the bulk at the same molar ratio of the reactants. The kinetics of the PP film formation were found to be governed by the concentration of the reactants in the bulk. The effect of HCl on the growth rate of PP films was also investigated. © 1994 John Wiley & Sons, Inc.     

Identification of inductive behavior for polyaniline via electrochemical impedance spectroscopy

Polyaniline (PANI) film electrodeposited in HCl medium using cyclic voltammetry (CV) with an upper potential limit of 0.90 V, exhibited an inductive behavior. PANI films deposited with different conditions were subjected to various applied potentials and the impedance characteristics were recorded through electrochemical impedance spectroscopy (EIS). The impedance results clearly reveal the existence of inductive behavior to PANI. Inductive behavior was observed for PANI films deposited with conditions which favor benzoquinone/hydroquinone (BQ/HQ) formation and further evidenced by X-ray photoelectron spectroscopy (XPS). A comparative analysis of the EIS and XPS results of PANI films prepared under similar conditions with the upper potential limits of 0.75 and 0.90 V, respectively, clearly documented that the presence of BQ/HQ, the degradation product of PANI, formed during the electrochemical polymerization at the upper potential limits causes inductive behavior to PANI.     

Effect of mineral and organic acids on radiation grafting of styrene onto polyethylene

A study has been made on the effect of mineral and organic acids on the radiation-induced graft polymerization of styrene onto low-density polyethylene films. Effects of different solvents and dose rate of irradiation on the grafting yield were also investigated. The influence of irradiation time and monomer concentration in the presence and absence of acid on the initial rate and grafting yield was studied. The dependence of the grafting rate on monomer concentration was found to be of the order 1.34 (in absence of acid), 0.61 (in presence of HCl), and 1.25 (in presence of oxalic acid). Such acid enhancement of the radiation grafting process is of practical importance from an economical point of view.     

高氯酸掺杂原位沉积聚苯胺薄膜的制备及性能研究

以高氯酸为介质酸,PVA为空间稳定剂,采用分散聚合方法,在玻璃表面原位沉积制得光滑半透明聚苯胺薄腰。研究了分散体系的反应过程、薄膜的表观形貌和微观结构、膜厚的影响因素、薄膜的电导率以及热稳定性能。结果表明:构成薄膜的聚苯胺粒子呈球型或椭球型;薄膜具有三级结构特征;高氯酸不仅作为介质酸,同时作为掺杂剂;薄膜的结晶性能不佳;薄膜厚度与介质酸的浓度并非线性关系;薄膜的电导牢处于半导体水平;电导率大小与无机介质酸的酸性强弱有一定关系,与表面形貌关系更为紧密;高氯酸掺杂聚苯胺薄膜在67.3℃时开始脱掺杂,在277.2℃脱除完全。     

Synthesis of fully and partially sulfonated polyanilines derived from ortanilic acid: An electrochemical and electromicrogravimetric study

The electrochemical polymerization of 2-aminobenzene sulfonic acid, also called ortanilic acid (o-ASA), on a gold electrode precoated with polyaniline (PANI), has been carried out. We proved that the electropolymerization of o-ASA is enhanced on PANI electrodes, resulting in thicker films obtained in aqueous media at room temperature. The electrosynthesized film (P(o-ASA)) was characterized by cyclic voltammetry, FTIR and nuclear magnetic resonance. The compensation of P(o-ASA) charge was evaluated using electrochemical quartz crystal microbalance combined with cyclic voltammetry, which showed that the electroneutralization process mainly involves cations. Additionally, copolymers of aniline and o-ASA were electrosynthesized, using a metallic electrode modified with PANI also as a working electrode. The degree of sulfanation of copolymers has been modulated with the proportions of monomers in the electrosynthesis solution. The studies reveal a more important participation of cations in fully sulfonated polyaniline than in partially sulfonated polyaniline.     

Enhanced microwave absorbing properties of lightweight films based on polyaniline/aliphatic polyurethane composites in X band

Polymer blends based on nanostructured polyaniline (PANI) doped with hydrochloric acid (HCl) and para‐toluene sulfonic acid (PTSA) introduced into aliphatic polyurethane matrix (PU) are synthesized to produce flexible thin composite films for microwave absorbers. The effects of dopant type, PANI content and film thickness on morphologies, dielectric and microwave absorption properties in the X‐band are studied. It reveals that real and imaginary parts of the complex permittivity are proportional to filler concentrations and type of doped PANI. The PANI‐PTSA/PU films show higher permittivity and better microwave absorbing properties than PANI‐HCl/PU for the same weight fraction of PANI. The minimum reflection loss RL_(dB) values for the PANI‐PTSA/PU are ?37 dB at (20% PANI and 11.6 GHz) and ?30 dB at (15% PANI and 11.3 GHz) for thicknesses of 1.2 and 1.6 mm, respectively. These high values of reflection losses make the obtained lightweight and flexible composites promising radar absorbing materials (RAM). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40961.     

Fabrication and properties of solution‐cast polyaniline/carboxymethylchitin blend films

Blend films consisting of polyaniline in emeraldine base form (PANI EB) dispersed in partially cross‐linked carboxymethylchitin (CM‐chitin) were prepared by solution casting, and characterized for their physical, thermal, and electrical properties. Homogeneous and mechanically robust blend films were obtained having PANI EB contents up to 50 wt % in the CM‐chitin matrix. FTIR spectra confirm intimate mixing of the two blend components. The thermal stability of the blend films increased with increase of PANI EB content, suggesting the formation of an intermolecular interaction, such as hydrogen bonding, between PANI EB and CM‐chitin chains. The addition of PANI EB into the pure CM‐chitin film resulted in a decrease in electrical conductivity of the films owing to disruption of ionic conduction of the CM‐chitin structure. After doping the blend films by immersion in HCl solution, the electrical conductivity of the HCl‐doped films increased with increase of the PANI EB content to a maximum value of the order of 10^?3 S/cm at 50 wt % PANI EB content. The electrical conductivity of the blend films was also dependent on the HCl concentration as well as on the type of acid dopant. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Hazardous acid detection based on chitosan‐grafted‐polyaniline copolymer

Polyaniline (PANI) has been utilized very well as an active material for hazardous acid detection device. Because its electrical conductivity is developing when it is doped with the protonic acid. However, a critical disadvantage of this material is its insolubility in general solvents so its processability is very poor. In this work, we prepared a Chitosan‐g‐PANI (Cs‐g‐PANI) copolymer to improve its solubility and prossability using common solvents and use film form of the final product to develop a sensitive device, which responds to the presence of hazardous acids. The synthetic Cs‐g‐PANI showing good solubility and excellent film forming properties was characterized by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, as well as X‐ray diffraction analysis, and scanning electron microscopy. The physical properties of Cs‐g‐PANI films were optimized by controlling the Cs composition. Constant potential was applied to this material for detecting the existence of hazardous acids such as hydrochloric acid (HCl), nitric acid, formic acid, and acetic acid. Our findings suggest that this device responds to the presence of HCl faster than any other acids. The detection mechanism is discussed in detail. POLYM. ENG. SCI., 59:E105–E110, 2019. © 2018 Society of Plastics Engineers     

Preparation and electroanalytical characterization of polyaniline: Polyacrylonitrile composite films

Electrically conducting composite films of polyaniline:polyacyrlonitrile (PANI:PAN) prepared with varying composition ratios of aniline mixed with a fixed amount PAN. The films of optimum thicknesses (0.10 mm) were obtained using an electrically operated automatic pressure machine. The films polymerized by oxidative polymerization using 0.1M potassium persulphate (K₂S₂O₈), undoped in 1M aqueous ammonia (NH₄OH) and doped in 1M hydrochloric acid (HCl). The conductivity of composite films was studied by keeping it in 1M HCl for different time period using 4-in-line probe DC electrical conductivity measuring instrument and the temperature dependence of DC electrical conductivity was studied using isothermal technique. The PANI:PAN composite film is used as a working electrode in an electrochemical cell. Chemically doped composite film is used as cathode (working electrode), aluminum metal foil as anode (counter electrode) and platinum foil as reference electrode. The electrolyte is of 0.05M aluminum chloride (AlCl₃) in dimethyl sulfoxide (DMSO). The voltage of the working electrode is stabilized with respect to the reference electrode and current applied between the working and counter electrode through a 9-V battery. The change in voltage versus time is plotted as the discharge curve and reversing the cell processes results in the doping of the composite films. The diffusion coefficient of the dopant ion (Cl⁻) present in the fully doped films were estimated by the galvanostatic pulse technique and found to bedifferent in different samples in the range of 10⁻¹⁶ to 10⁻¹² cm² s⁻¹. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Electrochromic properties of polyaniline thin film nanostructures derived from solutions of ionic liquid/polyethylene glycol

By exploiting the templating ability, wetting properties and the capability of the ionic liquid, 1-ethyl,3-methylimidazolium bromide to furnish the anionic dopant, nanostructured thin films of polyaniline (PANI) have been fabricated from an aqueous solution of the monomer encompassing this organic moiety by electropolymerization. These films have been compared to films synthesized from a medium based on a conventional polymeric surfactant, polyethylene glycol 400 (PEG). The template/dopant controls pore structure and assembly patterns as an interconnected network of nanofibrils of 50-500 nm in length and 10-40 nm in diameter constitutes the PANI films derived from the ionic liquid-based solution whereas the dominant microstructural attribute of the PANI films obtained from the PEG-containing formulation are abutting nanoparticles with elongated shapes. The effect of the different thin film nanostructures on their electrochromic properties is evident from the higher coloration efficiency, transmission modulation (in the NIR region), larger charge capacity, enhanced cycling stablity and faster color-bleach rates observed for the PANI films obtained from the ionic liquid medium as compared to that shown by the PANI films fabricated from the PEG solution. The outstanding optical and electrochemical behavior of the films, in particular, for the film derived from the ionic liquid-based solutions indicate that such recyclable and environmentally benign reaction media are most useful especially for transposing PANI films to large area substrates for electrochromic window applications.     

Environmental stability of electrically conductive viologen–polyaniline systems

Viologen–polyaniline (PANI) systems were prepared by PANI being coated onto viologen‐grafted low‐density polyethylene films. PANI in this system could undergo photoinduced doping with ultraviolet irradiation. The electrical stability of the electrically conductive viologen–PANI systems was found to be stable in air, but the conductivity decreased rapidly when the sample was treated in aqueous media of pH > 5 because of the migration of the anions out of PANI into water. However, the conductivity increased by a factor of 2 after treatment in a 1M HCl solution because of the further protonation of PANI by acid. The structural changes of these systems were monitored with ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and resistance measurements. The electrical stability of the viologen–PANI system in water could be enhanced via spin coating with poly(methyl methacrylate) (PMMA) because this layer inhibited the migration of the anions out of the system. The photoinduced doping of PANI could be carried out either before or after the spin coating of PMMA. The advantages and limitations of each method were demonstrated. A PMMA coating with a thickness of approximately 10 μm allowed a significant doping level to be achieved within a short period of irradiation and, at the same time, effectively shielded the film from the effects of the aqueous medium. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2099–2107, 2002     

One-dimensional growth and electrochemical properties of polyaniline deposited by a pulse potentiostatic method

One-dimensional growth of polyaniline (PANI) was conducted on carbon cloth through a pulse potentiostatic method. Hydrolysis of PANI was depressed, and the generated PANI film (PPM) displayed improved electroactivities. The specific capacitance of PPM was increased by 39% when compared to that of PANI film made by the conventional potentiostatic method (PM). The influences of the upper limit potential of the pulse potentiometry and the acidity of the polymerization solution on surface morphologies, electroactivities and conformation of the PANI films were studied by SEM, cyclic voltammetry, chronopotentiometry and UV-Vis spectrometry.