Polymerization of n-butyl vinyl ether photoinitiated by the initiator system poly(methyl phenyl silane)/N-ethoxy-2-methylpyridinium iodide/ZnI2/benzaldehyde

The cationic polymerization of n-butyl vinyl ether (BVE) in dichloromethane solution was initiated at room temperature by a photoinitiator system consisting of poly(methyl phenyl silane), PMPS, N-ethoxy-2-methylpyridinium iodide, EMP+I-, zinc iodide, ZnI2, and benzaldehyde, C6H5CHO. Concerning the initiation mechanism the photolysis of PMPS at wavelengths exceeding 340 nm was assumed to yield silyl radicals, the oxidation of which by EMP+ ions yields silyl cations. The latter reacts readily with I-, the counterion of EMP+ ion, thus producing terminal Si-I groups at the polysilane chains, Si-I groups can initiate the polymerization of BVE in the presence of ZnI2 and benzaldehyde. The formation of block copolymers consisting of MPS and BVE repeating units was confirmed by solvent extraction and H-1 NMR analysis.