Influence of electropolymerization conditions on the molecular weight of polyaniline

Successful attempts to produce high-molecular-weight polyanilines via electrochemical synthesis are reported. A systematic study of the influence of electropolymerization conditions on the weight-average molecular weight (Mw) showed that Mw of polyaniline varied only between about 22 000 and 40 000 g mol−1, even for a wide range of conditions. Significant increases in Mw are only obtained when a neutral salt is added to the electrolyte. Mw can be increased up to 160 000 g mol−1 by increasing the LiCl concentration to about 6 M. This salt effect on Mw is consistent with electrostatic charge screening effects.