The swelling (or deswelling) of a polypyrrole film due to the electrodoping
has been investigated by scanning tunneling microscopy (STM) in order to c
orrelate the surface morphological variations with the electroactivity of t
he film evaluated through its voltamperometric response. Different anions h
ave been used and the results obtained show a remarkable correlation betwee
n the magnitude of topographical features and the film electroactivity acco
rding to the physicochemical nature of counterions. Moreover the inclusion
of anions in the polymer matrix during the electrodoping induced strong mor
phological transformations in a micrometer scale. These experiments were pe
rformed in situ so as to reflect the solvation of the polypyrrole film and
the counterions. (C) 1999 Elsevier Science S.A. All rights reserved.