Dispersion polymerization of methyl methacrylate in supercritical carbon dioxide stabilized with poly(ethylene glycol)-b-perfluoroalkyl compounds

In this work selected components of an easily synthesible class of poly(ethylene glycol)-perfluoroalkyl block compounds were tested as stabilizers for the dispersion polymerization of methyl methacrylate in scCO(2). As already observed in the case of different block surfactants the anchor soluble balance (ASB) of the stabilizer is the crucial parameter affecting the efficacy of the stabilization and the kinetics of the polymerization process. When stabilizers with appropriate ASB were used, high molecular weight poly(methyl methacrylate) was synthesized under the form of microspherical polymer particles with yields ranging up to 80%. In these experiments the occurrence of a gel-effect was observed as a consequence of the shift in the locus of polymerization from the continuous to the dispersed phase due to an efficient capturing inside the polymer particles of the macroradicals initiated in the continuous medium. Collected experimental results suggest that the criteria for the rational design of novel surfactants for dispersion polymerizations in scCO(2) must be defined taking into account both the solubility of the stabilizer and its capability of effective anchoring to the surface of the polymer particles.