Emulsion polymerization using three types of RAFT prepared well-defined polymeric stabilizers based on 2-dimethylaminoethyl methacrylate (DMAEMA) under CO2 atmosphere: a comparative study

CO2-responsive latexes have attracted increasing attention because of their applications in various fields such as gels, surfaces, latex particles, membranes, worm-like micelles (WLMs). Herein, poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), poly(2-dimethylaminoethyl methacrylate)-block-poly(methyl methacrylate) (PDMAEMA-b-PMMA), and PDMAEMA-co-PMMA were synthesized through reversible addition fragmentation chain transfer (RAFT) solution polymerization, and applied as well-defined cationic stabilizers in emulsion (co)polymerization of styrene (St) and methyl methacrylate (MMA). Conducting reactions under CO2 atmosphere was attempted to produce polymer latexes which were susceptible to be triggered by CO2. The final latexes could be coagulated by N-2 bubbling, and subsequently redispersed by CO2 bubbling. Restoration of original size, and zeta-potential as confirmed by DLS resulted in successful redispersion of the polymer latex. The results showed that acid dissociation constant (pK(a)) has an effect on final conversion, and higher pK(a) leads to higher conversion and increase in rate of polymerization. Random distributions of MMA units in PDMAEMA-co-PMMA resulted in an increase in the pK(a) values causing facile protonation mainly due to the larger distance between nitrogen atoms.

Automated summary

CO2-responsive latexes were successfully synthesized through RAFT solution polymerization, allowing for coagulation and redispersion of the latexes under CO2 atmosphere. The pK(a) values played a significant role in the final conversion rate of the polymerization process.