Modeling of RAFT Copolymerization with Crosslinking of Styrene/Divinylbenzene in Supercritical Carbon Dioxide

A kinetic model for the reversible addition-fragmentation chain transfer radical copolymerization of vinyl/divinyl monomers in supercritical carbon dioxide, using a multifunctional approach for polymer network formation, is presented. The process is assumed to proceed as a dispersion polymerization in three stages, with two phases: CO2- and polymer-rich phases. A simple model for partition of the main components within the two phases is used. Experimental data of monomer conversion, molar mass development, evolution of gel fraction, and swelling of the polymer network for a styrene/divinylbenzene system, at 80 degrees C and 300 bar, are used to validate the model. Good agreement between model predictions and experimental data is obtained.