DOPING-INDUCED STRAIN IN POLYANILINE - STRETCH ELECTROCHEMISTRY

Dimensional changes in oriented and unoriented polyaniline induced by protonic acid doping or redox doping have been demonstrated. Sample el ongations upon doping are anisotropic in stretch-oriented material, wi th the greatest expansion in the direction perpendicular to the draw a xis. The observed electrochemical/mechanical phenomena are reversible for protonation/deprotonation and for redox cycling, although creep un der stress occurs in perpendicular and nonoriented samples under the l atter conditions. Limiting elongations are not dependent on the size o f the dopant ion, but the rate of protonic doping is slower for larger ions. Electrochemical doping, effected through constant current or co nstant potential, affords a high degree of control on the rate and ext ent of dimensional change and occurs with high coulombic efficiency ov er a range of current densities.