Development of CO2-Switchable Technologies for Polymer-Based Applications
CO2-switchable materials use CO2 as the trigger. Their mechanism is the reversible protonation of tertiary amines or amidines in aqueous solution, in the absence or presence of CO2. The application of CO2-switchable materials is also useful in other areas of polymer chemistry, such as ATRP (Atom Transfer Radical Polymerization) and the preparation of polymer latexes. Firstly, CO2-switchable ligands, solvents and photo-catalyst were used individually or jointly to recycle ligands and purify polymer made by ATRP. Secondly, artificial polymer latexes, such as poly(butyl methacrylate) (PBMA), were separately prepared from bulk polymers using the CO2-switchable solvents. The joint use of the two approaches mentioned above can produce polymer latexes with controlled molecular weight, but without impurities such as ligand or metal catalyst. Also, a new benign means was developed for reversibly breaking emulsions and latexes using CO2-switchable water, an aqueous solution of switchable ionic strength. Furthermore, living CO2-switchable 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 as the trigger.