Poly small diameter vessels

Methyl methacrylate (MMA) has been polymerized by dispersion polymerization in supercritical CO2 (204 bar and 65°C) using the polymer poly(FOA) as the surfactant stabilizer (8). Two polymeric stabilizers, a low-molecular-weight (LMW) (Mn = 1.1 X 10 g/mol) and a high-molecular-weight (HMW) (Mn = 2.0 X 10" g/mol) poly(FOA), and two different initiators [2,2 -azobis(iso-butyronitrile) (AIBN) and a fluorinated AIBN (F-AIBN)], were utilized. While product differences owing to changing the initiator were small, the presence of stabilizer had a pronounced effect. Without added stabilizer, the PMMA precipitated on the vessel walls and the reaction proceeded to low conversions only (<40%). When either LMW or HWM poly(FOA) was added as the stabilizer, the yield (>90%) and molar mass (> 3.0 x 10 g/mol) of the product increased dramatically. By increasing the concentration of the stabilizer, smaller and more uniform particles were created. At constant stabilizer concentration, the LMW stabilizer resulted in the formation of more particles with a smaller diameter than with the HMW poly(FOA). 

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