Synthesis of novel poly(amic acid) and polyimide with oligoaniline in the main chain and their thermal, electrochemical, and dielectric properties

Electroactive poly(amic acid), with oligoaniline in the main chain, was synthesized from macro-monomer of oligoaniline and p-phenylenediamine by oxidative coupling polymerization. The polymer characterization included Fourier-transform infrared spectra (FTIR), 1H nuclear magnetic resonance spectra (1H NMR) and gel permeation chromatography (GPC) as a determination of polymer structure, spectral analysis of different oxidation states via UV–visible spectra. Then the obtained poly(amic acid) was heated at 260 °C to induce cyclization, and transformed into polyimide materials. X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA) were used for the characterization of poly(amic acid) and polyimide materials. Moreover, poly(amic acid) and polyimide were tested in 1.0 M H2SO4 aqueous solution by cyclic voltammetry and they showed different electrochemical activity from each other. The prepared poly(amic acid) and polyimide doped with HCl exhibit a large enhancement in the dielectric constant in comparison to that of traditional polymers, ascribed to the improvement in charge delocalization of the polymers by introduction of the conjugated oligoaniline segments.