Patterns of conducting polypyrrole with tunable morphologies

An effective and reliable method was established to fabricate ordered arrays of conducting polypyrrole (PPy) with tunable morphologies. A polydimethylsiloxane (PDMS) stamp was used to lift up the top layer of silica spheres with a closed-packed hexagonal arrangement on a silicon wafer. The lattice spacing of the silica sphere array on the PDMS stamp could be tuned by controlling the swelling of the stamp. Afterwards, the silica spheres were transferred onto a poly(vinyl alcohol) (PVA) film which was pre-spin-coated on an ITO glass. The silica spheres were etched away with hydrofluoric (HF) acid, and the resulting porous PVA film maintained an identical ordered array but of holes. Electrochemical polymerization of pyrrole monomer was carried out with the ITO glass as a working electrode, on which was the PVA film with ordered holes. Different charge densities applied led to PPy patterns with different morphologies; a possible mechanism was addressed.