TRANSPORT-PROPERTIES IN POLYPYRROLE POWDERS AND IN PPY-PVA COMPOSITES- EVIDENCE FOR BIPOLARONIC CLUSTERS

Experimental results on electrical conductivity of both doped polypyrr ole (PPy) powder and conducting poly(vinyl alcohol) (PVA)-PPy composit e are presented. In each case, FeCl3 has been used as the oxidizing-po lymerizing agent. Results are interpreted on the basis of a model in w hich counter-ions act through their attractive potential by forming co nducting ways between chains and allowing transverse conduction. In th e case of PPy powder, the major contribution to conduction mechanisms is hopping between polaronic clusters. In the case of the composite, a n additional contribution results from fluctuation-induced tunneling t hrough thin insulating PVA barriers. (C) 1998 John Wiley & Sons, Inc.