CO ₂ -Switchable Surfactants in the Preparation and Application of Butyl Acrylate and Methyl Methacrylate Copolymer Latexes: Effect of Switchable Group Basicity on Polymerization and Coating Properties

CO2-switchable surfactants enable surface activity during processing but deactivate later, ideal for latex coatings where charged surfactants are used to stabilize the formulation, but the presence of charged species in the final coating negatively impacts the coating performance. In this study, surfactants with CO2-switchable functional head groups including imidazole (C12Im), tertiary aminoethoxy (C10EDMA), and tertiary amine (C12DMA), were applied in the emulsion copolymerization of butyl acrylate and methyl methacrylate using VA-061 as a CO2-switchable initiator. A lower-basicity surfactant produced larger latex particles, whereas higher-basicity surfactants stabilized smaller latex particles at lower concentrations. ATR-FTIR analysis indicated residual bicarbonate species in dried films, likely from the initiator, the most basic component. Coatings made with CO2-switchable surfactants exhibited improved water resistance, greater hydrophobicity, and enhanced corrosion protection relative to coatings with permanently charged surfactants. These findings highlight the critical role of surfactant basicity in governing both polymerization and coating performance.