Polymerization of aniline in the presence of DBSA in an aqueous dispersion

This paper describes a unique process of polymerization in an aqueous mediu m of an anilinium-dodecyl benzene sulfonic acid (DBSA) complex obtained by reacting aniline with DBSA prior to polymerization, The typical properties of the complex, appearing as fine needles, have been characterized and its polymerization behavior in the presence of DBSA upon addition of ammonium p eroxydisulfate in an aqueous medium was investigated by visual color inspec tion, UV-VIS spectroscopy and pH measurements. The polymerization process w as interrupted at different stages and polyaniline (PANI) powders were obta ined by precipitation with methanol. The powders morphology was investigate d using scanning electron microscopy (SEM) and their electrical conductivit y was measured on compression molded strips. UV-VIS and pH measurements sho w that the average oxidation state of the formed PANI chains vary during po lymerization from doped pernigraniline to doped emeraldine and correlate wi th the dispersion's color. In the beginning of the polymerization course, t he SEM studies show agglomerates consisting of spherical PANI particles. As polymerization proceeds, the voids among these particles are filled, formi ng a smooth surface of the PANI agglomerates, Simultaneously, the conductiv ity of the PANI powders increases with the polymerization time. (C) 1999 El sevier Science S.A. All rights reserved.