Chemistry and conductivity of some salts of polypyrrole

Abstract

The structure of the conducting salts of polypyrrole (PP) can be modified by a) introducing substituents to the pyrrole ring, b) changing the salt structure by base/acid treatment and c) changing the counterion distribution via control of the size and conformation of polymeric counterions. A new synthetic route to bicyclic compounds containing the pyrrole ring allows the synthesis of better ordered polymers, but with lower conductivities as observed for PP salts. The chemistry of acid-base-treatment is analyzed electrochemically; it is believed that OH − attacks the oxidized PP in ß-position. The most dramatic changes in conductivity behavior are seen in samples prepared with polystyrene-sulfunate counterions in the presence of varying amounts of non-solvent. By controlling the density of counterion chain, one is able to monitor the size and structure of internal barriers to charge carrier mobility.