Synthesis and reactions of polymers with photoactive terminal groups—3. The use of radical promoted cationic polymerization for the synthesis of poly( n-butyl vinylether) with n-acyl dibenz(b, f)azepine terminal units

Abstract

The free radical promoted cationic polymerization of n-butyl vinyl-ether (BVE) was achieved by the thermal decomposition of N-[4,4-azobis-(4-cyanopentanoyl)]-bisdibenz(b, f)azepine (ADBA) in the presence of diphenyliodonium hexafluorophosphate (Ph 2I +PF 6 −) or silver hexafluorophosphate (AgPF 6). Polymer samples prepared in the presence of AgPF 6 contained a significant number of terminal dibenzazepine units. Chain extension via dimerization of the dibenzazepine units occurred upon irradiating these polymers with u.v. light ( λ = 366 nm) in CH 2Cl 2 solution containing a triplet sensitizer (benzophenone or benzil). Polymer samples prepared in the presence of the iodonium salt contained only a very small fraction of macromolecules having dibenzazepine end-groups and were, therefore, not appropriate for the chain extension procedure.