Tuning the aggregation and redispersion behavior of CO2-switchable latexes by a combination of DMAEMA and PDMAEMA-b-PMMA as stabilizing moieties

Abstract

We have prepared CO2-switchable poly(methyl methacrylate) and polystyrene latexes where the stabilizing CO2-switchable moiety originated from either the monomer 2-dimethylaminoethyl methacrylate (DMAEMA) (copolymerized in situ) or previously synthesized poly(2-dimethylaminoethyl methacrylate)-block-poly(methyl methacrylate) (PDMAEMA-b-PMMA). The latexes can be aggregated by N2 and heat, and redispersed through CO2 bubbling and sonication. These two methods of incorporating the CO2-responsive groups yield quite different switching behavior. Using PDMAEMA-b-PMMA as the only switchable compound produced latexes that are easily aggregated, however the redispersion step required relatively high energy input. In contrast when the stabilizing moieties originated from DMAEMA monomer copolymerized in situ, the latexes exhibit the opposite behavior; aggregation is difficult but redispersion is easier. By combining the use of both in situ polymerized DMAEMA monomer and PDMAEMA-b-PMMA, we were able to produce latexes with tunable aggregation and redispersion behavior.