Transfer Reaction of the Two Propagating Species in Cationic Polymerization of Styrene by Acetyl Perchlorate or Trifluoromethanesulfonic Acid

Abstract

The transfer reaction of two differently dissociated propagating species towards m-xylene and methanol was investigated in the cationic polymerization of styrene by acetyl perchlorate or trifluoromethanesulfonic acid where the two species coexist. Transfer constants (ktx/kp) for these dissociated and nondissociated species were determined from the dependence of a bimodal molecular weight distribution of polymers on the transfer agent concentration. It was found that in CH2Cl2 the transfer constant for the nondissociated species is larger than that for the dissociated one. The latter value increased when the dissociation of the propagating species was suppressed by addition of a common-ion salt (nBu4NClO4) or a nonpolar solvent (CCl4). Dependence of the transfer constant on the nature and reactivity of the propagating species was discussed.