Oriented Conducting Polymers Prepared By Electrochemical Polymerization

An effective direction of charge transport is along a π-πstacking axis for conjugated polymers. This leads to anisotropic charge transport in crystals. It is common sense that the polymers present a very irregular structure of interacting chains with isotropy of conductivity. Therefore, large-area well-ordered organic semiconductor thin films are expected to have excellent charge transport behavior in the specific π-π stacking direction. We report the preparation of highly oriented conducting polymers through epitaxial electrochemical polymerization on highly oriented polymer films modified ITO. And then the structural and properties of the prepared oriented conducting polymers were characterized. The results are as follows:1. Electrochemical polymerization of 3-methylthiophene on highly oriented poly(vinylidene fluoride) (PVDF) film was achieved by cyclic voltammetry to yield well-ordered poly(3-methylthiophene) (P3MT) thin films with anisotropic structural and conductivity properties. The conductivity of P3MT along the direction perpendicular to the chain direction of PVDF, after electrochemical dedoping, is 59±3 S/cm, while that along the PVDF chain direction is 1.2±0.4 S/cm. The high conductivity of the P3MT is attributed to the well-ordered structure with its flat-on single crystals as confirmed by electron diffraction and Reflection Absorption Infra-red Spectroscopy (RAIRS). The data are consistent with P3MT chains aligned with π-π stacking perpendicular to the chain direction of the PVDF substrate. Epitaxial electropolymerization is an unusual method of preparing highly ordered thin films of organic semiconductors.2. Electropolymerization of aniline was carried out on highly oriented isotactic polypropylene (iPP) ultrathin films modified ITO electrode,epitaxial growth of an oriented PANI layer is achieved when sulfuric acid solution was used as electrolyte.