Surface Initiated Polymerization of Styrene from Carboxylic Acid Functionalized Polypyrrole Coated Electrode

Surface initiated radical polymerization (SIRP) is an elegant and efficient method to produce polymer
chains attached to surfaces with a high graft density. Growth of polymer chains from a gold surface
requires the formation of a self-assembled monolayer (SAM) of thiols functionalized by reactive groups
(alcohol or carboxylic acid) in order to covalently bind free radical initiator species. However, thiol desorption
induced by the temperature imposed for polymerization impedes the growth of polymer chains.Wepropose
therefore to coat a gold electrode with a polypyrrole (PPy) derivative containing carboxylic acid pendant
groups. The resulting conducting polymer layer was shown to be strongly attached to the surface. Grafting
of the initiator (azo compound) and SIRP of styrene were successfully performed on this organic layer, as
demonstrated by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry
(TOF SIMS), and contact angle measurements. The roughness, the morphology, and the surface uniformity
of the films were investigated by atomic force microscopy (AFM). Finally, cyclic voltammetry experiments
were carried out to study the influence of the polystyrene layer on the electrochemical behavior of the
conducting polymer