Polaron-Induced conformation change in single polypyrrole chain: An intrinsic actuation mechanism

Ab initio calculations show that a neutral polypyrrole chain in the ground state assumes a helical shape resulting from a novel bending mechanism, while upon oxidation the chain becomes planar within the polarons, an effect due to enhanced inter-ring pi bonding. This polaron-induced conformation change leads to an intrinsic potential for inducing macroscopic strains in the single chain, with implications for further theoretical studies and experiments. (c) 2005 Wiley Periodicals, Inc.