POLYMER-COATINGS BY ELECTROPOLYMERIZATION OF SOME VINYL MONOMERS

Electroinitiated polymerization coatings are uniform, thin, tightly ad herent, conformal, and economical to produce. This article describes u se of a novel (for electropolymerization) persulfate initiator to rapi dly polymerize a moderate T-g, crosslinked acrylic coating. Polymer co atings derived from the monomers acrylamide, acrylonitrile, and N,N'-m ethylenebisacrylamide were synthesized on an aluminum cathode by persu lfate electroinitiated polymerization at room temperature. The crossli nked polymer was brittle (T-g = 239 degrees C) but thermally stable (d egradation temperature = 310 degrees C). The coatings were spongy and contained some small cracks when polymerized at low current density (0 .1 mA/cm(2)). However, thicker coatings with fewer cracks were obtaine d at higher current densities. Persulfate was found to be an effective initiator for polymerization in this system, and the initiation mecha nism was confirmed to be free radical. In general, it appears possible to produce thin, uniform coatings on aluminum by this route. (C) 1995 John Wiley and Sons, Inc.