A study of acetoacetoxyethyl methacrylate hydrolysis in acrylic latex polymers as a function of pH

Acetoacetoxyethyl methacrylate (AAEM) is an ambient crosslinking monomer that, when incorporated into architectural coatings binders, provides coatings with improved hardness, scrub, stain, and dirt pick-up resistance. This study details the use of NMR spectroscopy to explore the hydrolysis profile of AAEM as a function of pH, type of neutralizer, and glass transition temperature of the binder. We have determined that AAEM has a hydrolysis profile that is independent of latex polymer pH relevant to coatings (pH 7–10). Lower T g latex polymers enable the diffusion of ammonia into the binder nanoparticles converting a larger amount of the acetoacetoxy moiety to the enamine form; this approach also allows for measuring the distribution of enamine and AAEM form in the latex polymer particle. The consequence of these findings is that AAEM may be utilized at a lower pH than previously envisioned without consequence to the hydrolysis profile of the acetoacetoxy functionality.