Using glycidyl methacrylate-linked poly(dimethylsiloxane), methyl methacrylate was polymerized in supercritical CO 2 . The effects of CO 2 pressure, reaction time, and mixing on the yield, molecular weight, and molecular weight distribution (MWD) of the poly(methyl methacrylate) (PMMA) products were investigated. The shape, number average particle diameter, and particle size distribution (PSD) of the PMMA were characterized. Between 69 and 483 bar, the yield and molar mass of the PMMA products showed a trend of increasing with increasing CO 2 pressure. However, the yield leveled off at around 345 bar and the particle diameter of the PMMA increased until the pressure reached 345 bar and decreased thereafter. With increasing pressure, MWD became more uniform while PSD was unaffected. As the reaction time was extended at 207 bar, the particle diameter of PMMA decreased at 0.48 ± 0.03% AIBN, but increased at 0.25% AIBN. Mixing the reactant mixture increased the PMMA yield by 18.6% and 9.3% at 138 and 207 bar, respectively.

Glycidyl methacrylate linked poly(dimethylsiloxane) (GMA-PDMS) was synthesized and used as a stabilizer for the dispersion polymerization of methyl methacrylate (MMA) in supercritical CO 2 . This study examined the effect of the concentrations of the stabilizer, 2,2'-azobisisobutyronitrile (AIBN) initiator, and MMA on the yield, molecular weight, and morphology of the poly(methyl methacrylate) (PMMA) product. PMMA was obtained in 94.6% yield using only 0.87 wt% GMA-PDMS. When the AIBN concentration was increased from 0.25 to 1.06 wt%, the molecular weight and particle size of the PMMA decreased from 56,600 to 21,600 and from 4.1 to 2.7 µm, whereas the particle size distribution increased from 1.3 to 1.9. The M n of the PMMA product ranged from 41,600 and 55,800 under typical polymerization conditions. The PMMA particle diameter ranged from 1.8 to 11.0 µm and the particle size distribution ranged from 1.4 to 1.8.