Properties of thin polystyrene-poly(2-cinnamoylethyl methacrylate) (PS-PCEMA) copolymeric coatings on gold electrodes

The characteristics of dip-coated polystyrene-poly(2-cinnamoylethyl methacr ylate) (PSn-PCEMA(m)) copolymeric coatings on Au wire and sputtered Au (on quartz crystals) electrodes have been investigated using TEM, cyclic voltam metry, mass measurements and ellipsometry. TEM studies of PS800-PCEMA(600) films, formed from an 86% cyclopentane (CP)/14% THF solvent, without subseq uent rinsing, are 70-85 nm thick and are in the form of micelles, ca. 40 nm in diameter. The coverage of Au by the PSn-PCEMA(m) micellar coating, esta blished using cyclic voltammetry in pH 7 solutions, increases with depositi on time and with the concentration of PSn-PCEMA(m) in the deposition soluti on. Also, the coverage is higher on smooth sputtered Au versus Au wires and for copolymers containing the greatest number of styrene units, independen t of the ratio of the number of PS to PCEMA units. Rinsing the PSn-PCEMA(m) coating with the block selective solvent after coating deposition rapidly decreases the coating density, thickness and surface coverage. An interesti ng feature of these coatings is that the copolymer (likely the PCEMA block) promotes the formation of a hydrous Au P-oxide film at anomolously low pot entials. (C) 2000 Elsevier Science Ltd. All rights reserved.