Reaction to effect the transformation of anionic polymerization into cationic polymerization: 3. Analysis of block copolymer formation by gel permeation chromatography

Abstract A study of the g.p.c. traces of AB poly(styrene- b THF) materials prepared by anion-to-cation transformation reactions has established conditions under which very narrow molecular weight distributions may be obtained. Dispersities as low as 1.04 were consistently obtained using directly brominated polystyrenes as initiators, and there is evidence that this value is an upper limit controlled by machine broadening. Dispersities of about 1.15 were registered with block copolymers prepared from xylylene-bromide-terminated polystyrenes, but in neither system was there any evidence for a chain scission process to generate homo polyTHF.