Copolymerization of VDF and HFP in Supercritical Carbon Dioxide: Experimental Analysis of the Reaction Loci

Free radical copolymerization reactions of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) were carried out in supercritical carbon dioxide at T=50 °C. When ammonium carboxylate perfluoropolyether surfactants were used, the formation of polymer particles was observed provided that HFP mole fraction in the feed was not larger than 0.30. Under these conditions, the effect of the total interphase area of the polymer phase, Ap, on the product propertieswas investigated by comparing experiments with largely different amounts of stabilizer, i.e., ranging from precipitation (smaller Ap) to dispersion (larger Ap) polymerization systems. We found that the copolymer molecular weight distribut…