Electropolymerization of nano-dimensioned polypyrrole micro-ring arrays on gold substrates prepared using submerged micro-contact printing

Cobaltabisdicarbollide-doped polypyrrole (PPy-[Co(C 2 B 9 H 11 ) 2 ]) nanostructures have been produced by directed, potentiostatic electropolymerization using a patterned combination of conducting and insulating thiols (4-aminothiophenol and octadecylmercaptan, respectively). The different conducting characters of both self-assembled monolayers guides the PPy-[Co(C 2 B 9 H 11 ) 2 ] deposition over the pattern. In this way we have produced doped, nanostructured annular polypyrrole rings, ∼400 nm high and ∼200 nm wide at full width-half maximum height. Two processes are thought to affect the polypyrrole growth; primarily, the different conducting characters of the self-assembled thiol monolayers, but also the hydrophobic interactions between the electrolyte and the self-assembled monolayer. The effects of the hydrophobicity of the doping anion were also studied by comparing the microstructures obtained for polypyrrole doped with the lipophilic [Co(C 2 B 9 H 11 ) 2 ] − anion and those doped with hydrophilic Cl − and ClO 4 − anions.