Bonding Mechanisms at Buried Interfaces between Carboxylic Polymers and Treated Zinc Surfaces

The interfacial bonding properties of carboxylic polymers on a Zn substrate have been investigated. Poly(methyl vinyl ether-alt-maleic acid monobutyl ester) and cured propoxylated bisphenol A fumarate unsaturated polyester were applied on a set of differently treated Zn samples. The buried metal polymer interface was studied by polymer removal and evaluation of the residue layers on Zn surfaces representing the metal polymer interface region. Additionally, the interfacial bondings were mimicked by adsorption of the representative carboxylic monomers, i.e., succinic and myristic acids. The differently treated Zn surfaces were found to be capable of adsorption of the carboxyl functionality of the polymers, resulting in formation of carboxylates. A comparison of the interfacial bondings by the residue layers of the polymers with those formed due to the molecular adsorption showed comparable adsorption mechanisms. Additionally, it was found that the polymer metal interfacial bonding density mainly depends on the Zn surface hydroxyl fraction, while Zn oxide semiconductor properties play an important role when a curing process occurs during the polymer interaction with Zn surfaces.