Surface monitoring of surfactant phase separation and stability in waterborne acrylic coatings

The stability of a waterborne acrylic coating has been studied paying particular attention to the effects of surfactants (SDS and Triton X-405). In a latex, surfactants are a minor component with respect to the polymer matrix, but they are of fundamental importance in stabilizing the polymer particles in the aqueous medium. When the coating has dried, they exude to the interfaces and self-assemble into hydrophilic aggregates that protrude from the film surface. The surfactant surface distribution has been monitored during thermal and light aging, and the changes observed have been investigated both in terms of the diffusion behavior of low molecular weight molecules in a polymer matrix and in terms of the chemical stability of the surfactants themselves.