Electropolymerization of 2-methacryloyloxy(ethyl) acetoacetate on aluminumusing a novel initiation method

Electropolymerization has been used as a method to form polymers on graphit e fibers and metals. Most of the previous studies have involved either the use of sulfuric acid as an initiator or direct reduction or oxidation of mo nomers to form the polymers. In this article, alpha-bromoisobutyronitrile ( BrIBN) was used as a new electrochemical initiator to form polymer coatings on an aluminum cathode. The reduction of BrIBN on a glassy carbon electrod e was examined using cyclic voltammetery. It was found that BrIBN could be reduced to isobutyronitrile radicals at potentials below the reduction pote ntial of water. The reduction behavior of BrIBN was found to be similar in aqueous, semiaqueous, and nonaqueous solutions. 2-Methacryloyloxy(ethyl) ac etoacetate was then electropolymerized on aluminum using the BrIBN as the i nitiator and lithium perchlorate as a supporting electrolyte. Defect-free c oatings were formed at half-cell potentials of less than -1.20 V. The effec t of various process variables on the polymerization kinetics under potenti ostatic conditions is reported. The coating thickness increased with polyme rization time, monomer concentration, and initiator concentration. A strong dependence of thickness on monomer concentration was observed. As expected , there was weak dependence on the initiator concentration. (C) 1999 John W iley & Sons, Inc.