Vibrational Spectroscopy of PTSA—Doped Polyaniline

Infrared transmittance spectra of polyaniline emeraldine base (EB) form and its different PTSA (p‐toulene sulphonic acid) concentration doped samples were measured in 4000‐400 cm−1 region at ambient temperature to reveal the polymeric chain oligomeric unit, interaction of sulphonate ions with these chains and effect of its concentration. The vibrational peaks of benzenoid (B) ring, quinoid (Q) ring, their combination modes and semiquinone units in PTSA doped emeraldine salts (PTSA:ES) are observed and assigned by using Oligomer Compound Approach. The para‐substitution of B rings is confirmed by the appearance of B ring C–H out‐of‐plane deformation mode as a medium intensity band at 827 cm−1 in EB and at 824 cm−1 in ES:PTSA salts. The out‐of‐plane wagging mode of five adjacent hydrogen in end capped phenyl group due to conformational deformation of rings in polymeric chain is obtained as very weak bands at 712 and 682 cm−1 in EB and PTSA doped salts. These studies showed that B4Q1 is the basic oligomeric u...