Living CO2-switchable poly(methyl methacrylate) (PMMA) latexes were prepared using reverse ATRP emulsion polymerization and AGET ATRP miniemulsion polymerization. The prepared latexes can be switched between the aggregated and dispersed states using only CO2 and any nonacidic gas (e.g., argon, air, nitrogen) as triggers. AGET ATRP miniemulsion polymerizations were enabled by the design and synthesis of a CO2-switchable ATRP inisurf, 1,1-(diethylamino)undecyl 2-bromo-2-methylpropanoate (BrC11N), which can generate stable emulsions under CO2 without requiring the addition of other emulsifiers. The resulting PMMA has controlled molecular weight and low dispersity.