Effects of high hydrochloric acid concentration on aniline chemical polymerization

The rate of aniline polymerization, measured by calorimetry, decreases when the hydrochloric acid concentration in the polymerization solution is increased from 2 to 6 M. The amount of chloride covalently bonded to the aromatic rings of the polymer backbone, estimated from the presence of new vibrational bands in the i.r. spectra, increases with an increment of hydrochloric acid concentration. The enlarged substitution on the polymer backbone is correlated with a decrease of the extension of the electronic conjugation, as shown by the shift towards higher energy of the broad band due to extended conjugation. The trend is related with a simultaneous decrease of the polymer d.c. conductivity. (C) 1997 Elsevier Science Ltd.