Bulk- and surface-initiated chemical in situ polymerisation of 2,5-dimethoxyaniline and 2-methoxyaniline on thiol-coated gold electrodes

We present the study of poly(2-methoxyaniline) and poly(2,5-dimethoxyanilin e) chemical deposition in situ on gold electrodes coated with self-assemble d thiol monolayers (SAM) containing different terminal groups: methyl, hydr oxy, and carboxy. The differences in the deposition rates of polymers on va rious thiol monolayers were investigated with the quartz crystal microbalan ce (QCM) and UV-Vis spectroscopy. It was found that for poly(2,5-dimethoxya niline) the polymer is formed in the bulk of the polymerisation solution an d subsequently or simultaneously it accumulates on the substrate surface. T he data obtained for poly(2-methoxyaniline) suggest substantially different mechanism of deposition. The polymerisation is initiated on SAM-modified g old, and this process is strongly influenced by the chemical nature of the monolayer. Thus, we observed large differences in the deposition rates on ' hydrophobic' and 'hydrophilic' monolayers modifying the electrode surface. The effect of the underlying thiol monolayer on the morphology of synthesis ed polymers was also investigated by atomic force microscopy (AFM). (C) 200 1 Elsevier Science Ltd. All rights reserved.