The polymerisation of functionalised methacrylate monomers in supercritical carbon dioxide

This paper describes the homopolymerisations of isobornyl methacrylate (IBMA) and poly(ethylene glycol) methacrylate (PEGMA) in supercritical carbon dioxide (scCO(2)) and copolymerisation with methyl methacrylate (MMA). We have used two different stabiliser systems poly(dimethyl siloxane) monomethylacrylate (PDMS-MMA) and Krytox 157FSL, both of which have been shown previously to be highly effective stabilisers for dispersion polymerisation in scCO(2). The effect of initiator concentration and copolymer composition is studied. For the copolymerisation of IBMA and MMA, under optimised conditions it is possible to form discrete particles with diameters in the range 1.4-3.6 mum. The PDMS-MMA macromonomer was found to be less effective as a stabiliser, causing particle aggregation due to the low solubility of this stabiliser in the monomers, The copolymers of PEGMA and MMA are also studied. The materials have interesting solubility properties with a transition in solubility from aqueous to organic media on increasing the MMA content. (C) 2003 Elsevier Ltd. All rights reserved.