Water Resistance Properties of Acrylic Polymer Films Using Polymerizable Surfactants

By Celine Burel, Wendy Lu, Madi Ngene, Remi Giordanengo, Romane Tranchard, Yuyi Liao, Lichang Zhou, Syensqo

The water resistance of waterborne all-acrylic and styrene acrylic dispersions is investigated at different T_gs. The performance of films obtained from latexes stabilized using conventional surfactants (SLS and Surf 1) is compared to that of latexes stabilized using polymerizable surfactants (PolySurf 1 and 2). The effect of the surfactant concentration and surfactant chemistry on the water whitening and water uptake of the latex films is studied. The surfactant chemistry and concentration, as well as the pH of the final latex have a significant influence on the water resistance results. The water whitening phenomenon is directly linked to the latex colloidal stability during drying and the excess of surfactant in the continuous water= phase. Atomic Force Microscopy (AFM) images revealed that labile surfactants can migrate within the film during drying and form hydrophilic pathways or pockets, making the film more susceptible to water at higher concentration of surfactants. Proton nuclear magnetic resonance (1H-NMR) analyses, combined with AFM imaging, showed that when polymerizable surfactant is used, due to its incorporation into the polymer backbone, the residual amount of surfactant in the continuous phase is low, resulting in films with superior water resistance. Moreover, the controlled distribution of the polymerizable surfactant on the latex particles results in a  more homogeneous distribution of the surfactant in the latex film lowering the water sensitivity of the films. Overall, for Tgs between -5 °C and 10 °C in acrylic latexes, the PolySurf2 exhibits superior water whitening and water intake performances as compared to conventional surfactants. PolySurf2 is designed to provide superior water resistance performances in clearcoats.