Advances in emulsion polymerization for coatings applications: Latex blends and reactive surfactants

The utilization of latex blends to prepare zero-VOC coatings and the use of reactive surfactants in emulsion polymerization are two advances in waterb orne technology that are of increasing interest to coatings formulators. Th e first part of this paper focuses on an investigation of the influence of the interface between high and low T-g latex particles on the gloss and sur face morphologies of films obtained from model latex blends. Gloss was infl uenced by the concentration of carboxyl groups present on the surface of th e latex particles (optimal concentration for maximum gloss 13% on the high T-g particles, the degree of neutralization of these groups (higher gloss w ith increased extent of neutralization), the type and concentration of the neutralizing base (higher gloss for stronger bases), and the presence of ad ded surfactant (higher gloss with added surfactant). Gloss was to be correl ated with the surface smoothness of the film. The kinetics, particle size, molecular weight, and location of the reactive surfactant after polymerizat ion, as well as the contact angle of films prepared from these latexes, are examined in the second part of this paper. The polymerization rate profile s were similar to those obtained using a conventional surfactant, however, the dependency of the rate on the number of particles was significantly low er. The amound bound increased and the molecular weight decreased with incr easing surfactant concentration.