Jm. Desimone et al., NEARCRITICAL AND SUPERCRITICAL FLUID SOLVENTS FOR LIVING ANIONIC POLYMERIZATIONS, Die Makromolekulare Chemie. Macromolecular symposia, 67, 1993, pp. 251-260
Near- and supercritical fluids are investigated as solvents for anioni
c polymerizations of 1,3-dienes. Solvent strength (solubility paramete
r) of mixtures of light hydrocarbons containing cyclohexane is shown t
o be adjustable using solvatochromic probe methods. The results indica
te that these mixtures have solubility parameter values that are lower
than conventional liquid solvents and represent a regime of solvent s
trength that has remained unexplored for ionic polymerizations. The an
ionic initiator 3-methyl-1,1-diphenyl-pentyllithium (MDPPL) was shown
to be soluble in supercritical ethane and that its ultraviolet/visible
absorption maximum was sensitive to systematic density changes of the
supercritical fluid induced by pressure profiling. These results were
extended to the anionic polymerization ot isoprene in butane/cyclohex
ane mixtures.