Much effort has been made over the past decades to improve the performance of waterborne formulations of coatings, adhesives, and inks. Latex polymer is one of the key resins or binders used in these applications, especially with pressure sensitive adhesives (PSA) and architectural coatings. Waterborne latexes are produced via emulsion polymerization, in which surfactants or emulsifiers are the key components to control latex properties such as particle size, and provide the stability of the latex polymer particles during the polymerization process and storage. Although surfactants are a necessary ingredient in the synthesis of latex polymers, they can cause negative effects during the final application. When latexes are used in coatings or adhesive applications, they form integrated polymer films to provide basic performance throughout the coalescence process. The surfactants migrate to the interfaces during film formation, either the air-film interface at the top of the film or the film-substrate interface at the bottom. Gloss or adhesion to the substrate can be affected by the migrated surfactants. The surfactants also migrate and form aggregates in the polymer film that create weak points and reduce performance indicators, such as lower water resistance. Therefore, much effort has been made to reduce the impact of surfactants on the performance of waterborne formulations. One of the promising approaches is to use polymerizable or reactive surfactants to replace conventional surfactants to prepare latex polymers.
A polymerizable surfactant provides dual functions during latex preparation. It functions as a conventional surfactant during emulsion polymerization and provides in-process stability. Meanwhile, a polymerizable surfactant contains reactive groups that are capable of covalently bonding to the latex polymer. In this study, a novel polymerizable surfactant product was developed and utilized to prepare latex polymers and resins through emulsion polymerizations. These polymers were then evaluated in PSA and architectural coating waterborne formulations. The results showed that the newly developed polymerizable surfactant almost fully reacted during the emulsion polymerization, and reduced or even eliminated the free surfactant migration during film formation, therefore improving performance of water resistance.