Spectroscopic and Molecular Weight Studies of Polytoluidines

Abstract

Poly(o-toluidine) and poly(m-toluidine) in base form have been characterized by infrared and ^lH NMR spectroscopy. Assignments of the proton NMR signals have been facilitated by the use of model compounds. The distinction between benzenoid and quinoid methyl resonances in the NMR permits a semi-quantitative estimation of the oxidation states of the polytoluidines. Infrared studies are consistent with a polyaniline-type backbone having pendant methyl groups. Field desorption mass spectrometry (FD-MS) was employed for estimation of the molecular weight of poly(o-toluidine). Gel-permeation chromatography of the same sample showed a bimodal elution pattern, suggesting that the FD-MS technique detects only the lower molecular weight fraction of the polymer. Despite this inherent limitation, FD-MS yields the interesting information that the polymer contains chains of both odd and even numbers of repeat units, necessitating the coexistence of different oxidation states in the base form of the polymer.