Study on Polymers Prepared by Chemical Oxidation of Aromatic Amines

Abstract

Synthesis, structure and properties of electrically conducting polymers from various aromatic amines were investigated. The amines include aniline (A), diphenylamine (DPA), Nphenylp-phenylenediamine (PPD), N, N'-diphenyl-p-phenylenediamine (DPPD), N-isopropylN'-phenyl-p-phenylenediamine (PrPPD) and N, N'-diphenylbenzidine (DPBz). The polymers prepared by chemical oxidation of the amines with ammonium peroxodisulfate in 2 moldm-3 hydrochloric acid were classified into two types, i. e. the polymers from A, PPD, DPPD and PrPPD (type I ) and the polymers from DPA and DPBz (type II). The conductivity of the type I polymers ranged from 10-^-1 to 10¹Sicrn, while that of the type II polymers was 10^-6-10^-4S/cm. From elemental analysis and infrared spectroscopy, the type I polymers w ere found to be substantially identical to polyaniline. In the formation of polyaniline, the radical cations of semiquinone type were assumed to play an important role. The type JI polymers were found to be composed of a copolymer of N-phenylaniline-N, 4-diyl based on N-C coupling and diphenylamine-4, 4'-diyl based on C-C coupling, . respectively. The polymers from A and DPPD showed ESR spectra with higher spin density, i. e.2.3 x 10²⁰ and 1.2 x10²⁰ spin/g, respectively, than the polymer from DPA, i. e.7.1 x10¹⁹ spin/g. The former two polymers showed higher temperature dependence of δH than the latter, suggesting motional narrowing of the spin.