Investigation of Molecular and Supermolecular Structure in Template-Synthesized Polypyrrole Tubules and Fibrils

摘要

Nanotubules and nanofibrils of polypyrrole were chemically synthesized using the pores of nanoporous polycarbonate membrane filters as'templates. We have previously shown that such "template-synthesized" nanofibrils of polypyrrole can have enhanced conductivities relative to more conventional forms of the polymer (e.g., thin films). Furthermore, we have shown that this enhancement in conductivity is critically dependent on the diameter of the nanofibrils; the narrowest diameter fibrils show the greatest enhancements in conductivity. In this paper we explore the genesis of this enhancement in conductivity by determining the relative conjugation lengths in the polypyrrole fibrils using FTIR and UV-visible-NIR spectroscopies. Using polarized infrared absorption and FTIR spectroscopies, we have followed the evolution of polymer chain orientation and conjugation length with polymer chain growth on the pore wall of the template membrane. On the basis of these results, we have proposed a bilayer model to explain the enhancement in conductivity and its strong dependence on fibril diameter.