DISPERSION POLYMERIZATION OF METHYL-METHACRYLATE STABILIZED WITH POLY(1,1-DIHYDROPERFLUOROOCTYL ACRYLATE) IN SUPERCRITICAL CARBON-DIOXIDE

The reaction parameters and progress of the dispersion polymerization of methyl methacrylate (MMA) utilizing poly(1,1-dihydroperfluorooctyl acrylate) [poly(FOA)] as a polymeric stabilizer in supercritical CO2 w ere investigated. Spherical and relatively uniform polymer particles w ere formed. Poly(methyl methacrylate) (PMMA) latex particles with diam eters ranging from 1.55 to 2.86 mu m were obtained with poly(FOA) stab ilizer [M(w) = 1.0 (+/- 0.4) x 10(6) g/mol] concentration from 16 to 0 .24 wt %. Investigations of the particle size and conversion as a func tion of reaction time indicate that a gel effect occurs between 1 and 2 h of reaction time. In addition, the particle diameter increases wit h an increase in monomer concentration, presumably due to an increase in the solvency of the reaction medium. Dispersion polymerizations of MMA carried out under different pressures (145-331 bar) produced latex particles with similar diameters, molecular weights, and yields, sugg esting that the results are insensitive to the pressure under the reac tion conditions investigated. In addition, the phase behaviors of poly (FOA) were thoroughly investigated. Cloud point experiments indicate l ower critical solution temperature (LCST) phase behavior for the poly( FOA)/CO2 system with much higher polymer, solubilities than for hydroc arbon polymers.