SELECTIVE DEPOSITION OF CONDUCTING POLYMERS VIA MONOLAYER PHOTOPATTERNING

Upon electropolymerization of the corresponding monomer, patterns of polyaniline, poly(3-methyl-thiophene), or polypyrrole replicate the pattern formed by selective irradiation of a photosensitive monolayer confined to an electrode surface. Irradiation of monolayers of bis[11-(4-azidobenzoyl)oxy]-1-undecyl disulfide, I, on Au in the presence of various primary or secondary amines results in the attachment of the amine in very high yields. Irradiation of Au-I substrates through a mask results in a patterned monolayer. Electrodeposition of aniline from aqueous solution, or 3-methylthiophene or pyrrole from CH3CN, results in polymer deposition preferentially on the nonirradiated regions of the surface. Polymer patterns are characterized by optical microscopy and by stylus profilometry. Cyclic voltammetry and X-ray photoelectron spectroscopy are used to measure deposition contrast and show that under certain electrochemical conditions the ratio of polymer deposition on nonirradiated monolayer regions to irradiated monolayer regions is greater than 1000:1. Cyclic voltammetry of the monomers, Fe(CN)(6)(3-/4-), and N,N,N',N'-tetramethyl-1,4-phenylenediamine(2+/+/0) shows that electron transfer rates are attenuated on monolayers of Au-I compared to bare Au and are decreased further on monolayers of I irradiated in [CH3(CH2)(3)]2NH or [CH3(CH2)(7)]2NH. Differences in electron transfer through these monolayers agree with the polymer patterning results and are shown to be the principal reason for selective polymer deposition on these photopatterned monolayer substrates.