Dispersion polymerization of styrene in supercritical CO2 in the presence of non-fluorous random copolymeric stabilizers

The non-fluorous random copolymers, poly (3-[tris(trimethylsilyloxy)silyl]propyl methacrylate-co-2-dimethylaminoethyl methacrylate) (poly(SiMA-co-DMAEMA)) and poly (3-[tris(trimethylsilyloxy)silyl]propyl methacrylate-co-diisopropylaminoethyl methacrylate) (poly(SiMA-co-DPAEMA)) were prepared with different comonomer compositions and utilized as stabilizers in the dispersion polymerization of styrene in supercritical carbon dioxide (scCO2). The copolymers were found to provide an effective stabilization on the polystyrene (PS) latexes in scCO2. Poly(SiMA-co-DMAEMA) (71:29) were proved to be optimal among (86:11), (71:29), and (57:33) comonomer compositions to produce micron-sized spherical PS particles with higher yields. Poly(SiMA-co-DPAEMA) having higher methyl branching in the DPAEMA pendant group provided a better stabilization compared to poly(SiMA-co-DMAEMA). The effect of varying concentration of stabilizer and monomer upon the polymerization yield, molar mass, and morphology of PS have been investigated.