Electrografting of poly carbazole-co-acrylamide onto highly oriented pyrolytic graphite. A cyclovoltammetric, atomic force microscopic and ellipsometric study

Ž . The electrocopolymerization of carbazole and acrylamide on highly oriented pyrolytic graphite HOPG from ACN solutions Ž . via cyclovoltammetry CV was studied in order to evaluate the possibility to deposit uniform and thin but pinhole-free and still reactive coatings onto graphite-like substrates. The morphology of the coatings was investigated using atomic force microscopy and the coating thicknesses and optical parameters were measured using ellipsometry. It was found that under the chosen Ž . Ž . conditions thin coating thickness h 180 nm and relatively smooth root mean square surface roughness RMS 150 nm f Ž . P Cz-co-AAm -coatings exhibiting a uniform globuoidal morphology can be deposited onto graphite. From a certain coating Ž . thickness h 50 nm no pinholes could be detected. It was found that the thickness of the deposited coatings increases almost f Ž linearly with increasing number of CV-cycles while keeping all other experimental parameters scan rate and comonomer . concentration ratio constant. No influence of the comonomer concentration ratio on the film thickness and coating appearance could be observed, however, at quite low initial concentrations. However, the CV-scanning rate has quite a significant influence Ž . Ž . on the thickness of the deposited coatings. Higher scan rates 100 mV s result in thin h 22 nm coatings whereas at lower f Ž . Ž scan rates 50 mV s coatings with thicknesses of approximately 50 nm were obtained. The optical coating parameters the . refractive index n and extinction coefficient k seem to be independent of the deposition parameters and therefore averaged values of n 1.54 0.03 and k 0.08 0.03 were obtained. 2001 Elsevier Science B.V. All rights reserved.