Emulsion polymerization of aniline

In this communication, we report that aniline can be conveniently polymerized directly into conducting material using an emulsion polymerization technique. The polymerization is carried out in non-polar or weakly polar solvents in the presence of a functionalized protonic acid that acts simultaneously as a surfactant (emulsifier) and as a protonating agent (dopant) for the resulting electrically conducting polyaniline. It was found that the present direct, one-step preparation of polyaniline-protonic acid complexes in organic solvents may lead to polyaniline with significantly higher molecular weight than that prepared in acidic aqueous solutions. In addition, the present polyaniline-functionalized acid complexes displayed higher solubilities in non-polar or weakly polar organic solvents than corresponding complexes obtained by mechanically mixing the emeraldine base form of polyaniline with the protonic acid. Films cast from concentrated solutions routinely exhibit conductivities in excess of 100 S cm−1. Additionally, it was found that, using the emulsion polymerization route, polyaniline-functionalized protonic acid complexes of fibrillar morphology can be produced, which have an exceptional degree of crystalline order and orientation.