Investigation of heterogeneous radical polymerization of methyl methacrylate with polydimethylsiloxane as stabilizing agent in supercritical CO2 by turbidimetry

Experimental results of a turbidimetric in situ investigation of the heterogeneous radical polymerization (dispersion polymerization) of methyl methacrylate and polydimethylsiloxane–monomethacrylate in supercritical carbon dioxide are presented. The experiments were carried out at 60 °C and 330 bar. Turbidity spectra were measured directly in the autoclave to determine the average particle diameter σ_τ and the particle density N_AV/V during the first five minutes of polymerization. The results show that the particle density increased until a maximum was achieved, whereas the particle diameter increased during the first stage. Moreover, a comparison with kinetic data suggests that the particles nucleate through coagulation of polymer that is formed in the homogeneous phase. Copyright © 2001 John Wiley & Sons, Ltd.