Reactivity of B(C6F5)3 towards glycidol: The formation of branched cyclic polyglycidol structures

Abstract

B(C6F5)3 is a strong electrophilic catalyst that promote the ring-opening polymerization of a number of epoxides via the formation of zwitterionic growing chains. Cyclic chains frequently are the major component of the reaction, which makes this synthetic route a viable strategy for the generation of cyclic polyethers in large quantities. We present a systematic study on the bulk and quasi-bulk polymerization of glycidol with B(C6F5)3, including kinetic experiments that evidences an abrupt chain growth at high monomer conversions. Ring fusion and branching mechanisms are invoked to explain such phenomenology. Branched cyclic polyglycidols (bcPG) are the major compounds with Mn up to 8 kg/mol and Ð ∼ 2. The glass transition temperature of bcPG exhibits lower values than that of reference linear PG samples likely associated to the dominating effect of branches.