Piloting of anionic polymerization of styrene in tetrahydrofuran

Anionic polymerization of styrene in THF with n-butyllithium/alpha-methylst yrene initiator is described as a first step in preparation of a styrenic b lock copolymer. In order to suppress rapid decay of living alpha-methylstyr ene unimers, which occurred at room temperature, the initiation reaction wa s carried out at -20(+/-5)degrees C. The kinetic parameters of this decay r eaction were determined and used for process optimization. By combining exp eriments with modelling of styrene propagation reaction all key process par ameters were defined for 1-L, 38-L, and 189-L reactors. A good march was de monstrated between the model and experimental propagation exotherm for semi batch reaction conditions. Overall, it was demonstrated that technical grad e THF and styrene could be used at pilot plant scale to prepare well-define d polymers up to Mn 22 000 via the "living" polymerization mechanism. The r esulting polymers had narrow molecular weight distributions (1.06 < Mw/Mn < 1.30).