POLYMERIZATION OF N-BUTYL VINYL ETHER PHOTOINITIATED BY THE INITIATORSYSTEM POLY(METHYL PHENYL SILANE) N-ETHOXY-2-METHYLPYRIDINIUM IODIDE/ZNI2/BENZALDEHYDE/

The cationic polymerization of n-butyl vinyl ether (BVE) in dichlorome thane solution was initiated at room temperature by a photoinitiator s ystem consisting of poly(methyl phenyl silane), PMPS, N-ethoxy-2-methy lpyridinium iodide, EMP+I-, zinc iodide, ZnI2, and benzaldehyde, C6H5C HO. Concerning the initiation mechanism the photolysis of PMPS at wave lengths exceeding 340 nm was assumed to yield silyl radicals, the oxid ation of which by EMP+ ions yields silyl cations. The latter reacts re adily with I-, the counterion of EMP+ ion, thus producing terminal Si- I groups at the polysilane chains, Si-I groups can initiate the polyme rization of BVE in the presence of ZnI2 and benzaldehyde. The formatio n of block copolymers consisting of MPS and BVE repeating units was co nfirmed by solvent extraction and H-1 NMR analysis.