An Experimental Study on the Free-Radical Copolymerization Kinetics with Crosslinking of Styrene and Divinylbenzene in Supercritical Carbon Dioxide

A study on the effect of process conditions and composition of the reacting mixture on the kinetics and particle properties in the copolymerization of styrene and divinylbenzene in supercritical carbon dioxide is presented. Polystyrene-block-polydimethylsiloxane and Krytox 257 FSL (Dupont) were used as stabilizers, and their performance compared. A 38 mL, high-pressure view cell, equipped with one frontal and two lateral sapphire windows, was used as the reacting vessel. The polymer product was characterized for total monomer conversion, gel content, molecular weight averages of the sol fraction and particle size distribution. Acceptable polymerization rates and partially-agglomerated spherical particles were produced under the conditions tested.