OXOAMINIUM SALTS AS INITIATORS FOR CATIONIC POLYMERIZATION OF VINYL MONOMERS

Oxoaminium salt (1), derived from 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, 2) by one-electron oxidation, could be an initiator for cationic polymerization of vinyl monomers such as isobutyl vinyl ether (IBVE), 2,3-dihydrofuran, p-methoxystyrene, N-vinyl pyrrolidone, etc., to give the corresponding polymers, when 1 had a low nucleophilic counter anion. Formation of the adducts of 1 and IBVE as well as H-1-NMR and IR data suggested the formation of polymers containing N - O - C structure as the polymer head group. In the polymerization of IBVE, the effects of solvent and concentration of 1 were little observed, however the polymerization rate was dependent on temperature. Furthermore, the thermal reaction of the polymers obtained, which were regarded as prepolymers for block copolymerization and polymeric initiators for radical polymerization, was studied. For example, poly(2-benzylidene-1,3-dioxane) obtained by the polymerization of 2-benzylidene-1,3-dioxane with oxoaminium hexafluoroantimonate (1, X = SbF6) was employed as an initiator for radical polymerization of MMA to give its block copolymer with PMMA.