CATIONIC POLYACRYLAMIDE ADSORPTION ON EPOXY SURFACES

The adsorption of a cationic polyacrylamide (acrylamide/beta methacryl oxyethyltrimethylammonium methyl sulfate copolymer) onto an imidazole catalysed bisphenol-A based epoxy resin surface was examined by surfac e wetting, The work of adhesion of diodemethane, ethylene glycol and w ater was measured on microscopically smooth epoxy surfaces using a Wil hemy plate method, in both advancing and receding modes, The cationic polyacrylamide was adsorbed from aqueous solutions as a function of th e pH of the solution, In addition to the cationic quaternary amine gro ups along the polymer chain, there were carboxylate groups from amide hydrolysis, which had a pK(a) of 10.73. The surface wetting of neither diodomethane nor ethylene glycol was sensitive to the adsorbed polyac rylamide, Wetting of the surface by water was very sensitive to the pr esence of adsorbed polyacrylamide. Polyacrylamides in solutions below pH 9 adsorbed onto the epoxy surface resulting in increased water adhe sion to the surface, When the polyacrylamide solution was greater than pH 9 carboxylate groups ionized and the anions inhibited adsorption o f the polyacrylamide. The water wetting measurements were shown to cor relate with the adsorption of Pd/Sn colloidal particles used for elect roless deposition of copper circuit lines on printed circuit boards. ( C) 1997 Academic Press