Surface Pretreatment for Electrochemical Fabrication of Ultrathin Patterned Conducting Polymers

Polypyrrole grows effectively along the glass ubstrates pretreated withn-alkylsilane r agents in etectropolymeriza-tion from aqueous olutions, resulting in the formation of an ultrathln polypyrrole film at twin-microband electrodes. However, no effective promotion of lateral growth of polypyrrole was observed when the substrate was pretreated with 3-aminopropyltriethoxysilane or when the electrolysis was conducted in acetonitrile, suggesting hatthe hydrophobicity of the substrate is essential for promotion of the lateral growth of polypyrrole. The promotion effect is accounted for by adsorption of pyrrole monomers and selective deposition of intermediate oligomers at the hydrophobic surfaces. The polymerization anisotropy (the ratio of lateral growth rate to vertical growth rate) was ca. 25. The partial pretreatment provided a way of micropatterning with polypyrrole on an insulating substrate. Such a promot ion effect at hydrophobic surfaces is amplified in the presence of a small amount of an anionic surfactant. Polyaniline also grows effectively along the hydrophobie surface with the polymerization anisotropy of>i00. Electrically conducting organic polymers have been studied extensively over the last decade. 1 Of these poly-mers, conducting polymers electrochemically synthesized such as polypyrrole and polyaniline have received particu