Cure-Dependent Morphology of Acrylic/Alkyd Hybrid Latex Films via Nanomechanical Mapping

Acrylic/alkyd hybrid latexes offer the potential to obtain hard films from waterborne polymer dispersions without using coalescing agents. However, despite being widely used commercially, the curing process of the alkyd resin used in such formulations, and its influence on the final film morphology, remain poorly understood. In this work, we explore the curing process and its influence on film morphology in alkyd/acrylic hybrid latexes by nanomechanical mapping of the film during curing. It is shown that, although acrylic domains aid oxygen diffusion and facilitate curing, the rate of curing was substantially lower in the interior. Nevertheless, homogeneous curing was achieved at long times. The role of primary and secondary catalysts in the process is also explored, finding that the variation of the rate of curing of the alkyd plays an influential role in the development of film structure due to phase migration of the two polymers as curing progresses. It is hoped this work goes some way to unraveling the mystery behind the curing process in acrylic/alkyd hybrid latex films.