Electrically Conductive Polymer Composite from Polypyrrole and Electrodeposited Poly(p-phenylene terephthalamide) Film

Abstract

Electrically conductive composites from polypyrrole (PPy) and poly(p-phenylene terephthalamide) (PPTA) were formed by electropolymerization of pyrrole on the electrode covered with PPTA film prepared by electrolysis of PPTA polyanions dissolved in dimethylsulfoxide. For the PPTA film annealed above 250°C, the polymerization of pyrrole hardly took place. Based on DSC measurements, it was found that the remaining solvent of PPTA film was closely related to composite formation. The morphologies of the composites varied, depending on the supporting electrolytes of tetraethylammonium p-toluenesulfonate and lithium perchlorate. The conductivity of the composite was 5–50 S cm−1. The composite showed improved mechanical properties: tensile strength was 142 MPa and tensile modulus was 6.2 GPa for the PPy(TsO−)/PPTA composite, where TsO− denotes the p-toluenesulfonate ion. The temperature dependence of the dynamic viscoelasticity of the PPy(TsO−)/PPTA composite was well explained by Takayanagi’s two-phase model, which was also consistent with SEM observation. The conductivities of the composites doped with p-toluenesulfonate and perchlorate were both retained at all times up to 150°C, whereas that of the pure PPy film decreased to 80% the original value after annealing at 150°C, being independent of the dopants. PPTA film was dimensionally stable and heat-resistant, and these properties provided a stable conductive composite film.