Enhancing the colloidal stability of carboxylated styrene-acrylic latexes using anionic and nonionic polymerizable surfactants for architectural paints

Abstract

To overcome the main challenge of low colloidal stability of poly(styrene-co-butyl acrylate-co-acrylic acid-co-acrylamide) latexes in the presence of polymerizable surfactants, this study aimed to obtain latexes with superior properties and coagulum-free through semibatch emulsion polymerization using anionic and nonionic polymerizable surfactants (Maxemul^TM 5010 and Maxemul^TM 6106) mixed with a conventional anionic surfactant (Dowfax^TM 2A1). The effect of the surfactant amount and type on the colloidal stability, particle size, electrolyte stability, water absorption of the polymer films, and wet scrub resistance of the paint films were investigated. The water absorption of polymer films containing a blend of polymerizable and conventional surfactants was compared to that of films containing conventional surfactants. The results showed that the molar mass has a significant impact on latex stability during the early stages of polymerization. By incorporating a chain transfer agent (n-dodecyl mercaptan, DDM) within the range of 0.05-0.2 wt% loaded in the reactor charge based on the total formulation, coagulum-free latexes were obtained. When polymerizable surfactants were used together with a conventional surfactant and DDM, stable latexes with particle sizes ranging from 96.5 to 110.0 nm, enhanced film properties, and better scrub resistance of the paint films were obtained. The increase in polymerizable surfactant improves the electrolyte stability of the latexes but increases the water absorption of the polymer films. The use of polymerizable surfactant helps to reduce the total amount of surfactant used in the latex formulation. The results achieved in this study create a new approach for the synthesis of poly(St/BA/AA/AM) latexes using polymerizable surfactants for highly pigmented architectural paints.