SYNTHESIS OF HIGHLY SULFONATED POLYANILINE

An alternative approach to synthesize sulfonated polyaniline (SPAN) is described. This route results in higher sulfur-to-nitrogen ratio (S/N ratio up to about 3/4 compared to 1/2 for the original route) and higher yield (about 70%). Compared to the SPAN prepared via the previous route, the new SPAN has higher solubility (approximately double), higher d.c. conductivity (about one order higher), nearly pH-independent d.c, conductivity in the region of 0 less than or equal to pH less than or equal to 14 (while emeraldine salt has a sharp drop in d.c. conductivity to an insulator at pH similar to 3 and the SPAN made via the previous route becomes semiconducting at pH similar to 7.5), a different pH dependence of the cyclic voltammogram spectrum, and other novel properties, The relationship of these improved physical properties to the change of synthetic route is suggested.