Fabrication And Formation Mechanism Of Conducting Polyaniline And Its Composite Films Based On Textile Substrates

As one of the most promising electrically conducting polymers, polyaniline (PANI) has been focused by researchers due to its excellent properties such as structural diversity, unique doping mechanism and good environmental stabilities. Although PANI has been studied deeply in terms of its structure and properties, its wide application has been restricted for its poor processability with strong rigidity of chains, low solubility in most common solvents, unstably at melt processing and difficulty in forming. Preparing PANI composites with other traditional materials such as plastics, rubbers, fibers, et al, provides one main mean to resolve the above problems, the traditional materials can been added new features with special properties of polyaniline. By this method, it has been applied an important mean to broaden the applications of polyaniline and traditional materials. Combining the performances of PANI or its composites with traditional textiles plays a key role in the exploitation of new functional textiles.In this paper, in-situ film forming methods were utilized in the full-text. The thermodynamics and dynamics of aniline monomers adsorbed onto fibers were investigated and in-situ polymerization mechanism of PANI on textile substrates was also discussed. Optimization of film-forming conditions such as monomer concentration, adsorption time, adsorption temperature, pH value of monomer solution, molar ratio of oxidant/monomer, molar ratio of acid/oxidant, oxidant temperature, dipping time into the oxidant solution, were carried out. Thus preparation conditions of uniform PANI films on a large surface area determined.A method consisting of hydrothermal growth and in-situ polymerization ways were used to preparing PANI/ZnO composite films, in which ZnO nanorod arrays were formed firstly on textile substrates and in-situ polymerization of PANI occurred after monomer adsorption step. Effects of heating temperature for nanoseed coating forming, zinc salt concentration in the hydrothermal solution and hydrothermal reaction time on the preparation of ZnO nanorod arrays, were investigated. Formation conditions of PANI films on the surface of inorganic film-coated textiles, such as monomer concentration, adsorption time, adsorption temperature, molar ratio of oxidant/monomer, were also determined. Adsorption behavior of aniline monomers onto ZnO-coated textiles was analyzed. Deduced from the characterization results, hydrogen bonding may be created between the N-H groups in PANI molecular and ZnO in the inorganic film, and the higher ordered PANI molecular chains were fabricated on the ZnO inorganic array skeleton than those formed on the surface of fibers. Textiles coated with PANI/ZnO composite films showed better antistatic and anti-ultraviolet properties than the samples overlaid with single film.Copper metal layers were created on the PANI-coated fabrics by means of electrodeposition and electroless deposition methods respectively to fabricate PANI/Cu composite films on textile substrates. In terms of electroless deposition way, details in the composition, structure and morphology of PANI films before and after sensitization-activation step were compared to understand fully the specific role of PANI films in the process of electroless deposition. Effects of molar ratio of oxidant/monome during in-situ polymeration step, concentrations of main salt, reductant, complexing agent and additives, pH values and reaction temperature on Cu deposition rate and sheet resistance were discussed and the proper conditions for PANI/Cu preparation were determined. Characterization results showed that the rough structure of PANI film promoted the metal particles growing in a limited space to form small particles and the ultrasonic-assisted way played an important role in the formation of small grains and its uniform dispersion, which can enhance stirring the solution. Textiles coated with PANI/Cu composite films produced by electroless plating showed better bonding performance and corrosion resistance than with Cu coating only.The electrochemical behavior of PANI film based on textiles in the electrolyte solution was investigated by cyclic voltammetry, linear sweep voltammetry and chronopotentiometry. The results showed that a pair of cathode and anode current peak occurred, which was corresponding Cu precipitation and dissolution reaction respectively. Concentration of main salts had noticeable effects on the polarization of electrodeposition process. When current density was60or80mA/cm2, E-t curve showed the typical characteristics of growth type of metal nucleation. Effects of forming conditions such as concentrations of main salt, conductive salt and complexing agent, current density and pH value on Cu deposition rate and sheet resistance by constant current mode. Results indicated that Cu layers with the layered structure grew intertwined with PANI polymer coating and had a relatively high deposition in case of current density at60～80mA/cm2. PANI moleculors in PANI/Cu formed by electrodeposition showed mainly in the form of reduced state, in which more strong bond created between the N atoms with Cu particles than in that fabricated by electroless deposition.