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The cationic polymerization of cyclic ethers such as cyclohexane oxide (CHO) and vinyl monomers such as butyl vinyl ether (BVE) and N-vinylcarbazole (NVC) is initiated upon irradiation at A 380 nm in CH,CI, solution containing an allylic sulfonium salt, namely, 2-ethoxycarbonyl-2-propenylthiophenium hexafluoroantimonate (1) (EMT'SbF;), and one of the following compounds: benzophenone, anthracene, thioxanthone, perylene or phenothiazine. Electron transfer and hydrogen abstraction mechanisms were proposed for the initiation step. Stable cation radicals of phenothiazine were also prepared, and the cationic polymerization of butyl vinyl ether was initiated by these cation radicals.

Poly(methy1 phenyl silane) was used to photoinitiate the polymerization of methyl methacrylate. Poly(methy1 methacrylate) (PMMA), obtained this way, contains remaining polysilane chains. Photolysis of this PMMA in the presence of vinyl monomers such as styrene makes it possible to prepare block copolymers. Such PMMA prepolymers were also used to induce the polymerization of cyclohexene oxide through formation of PMMA-attached silyl radicals and subsequent oxidation to the corresponding ions in the presence of N-ethoxy-2-methylpyridinium hexafluorophosphate resulting in the formation of a block copolymer. ZUSAMMENFASSUNG:Methylmethacrylat wurde mit Poly(methylphenylsi1an) als Photoinitiator polymerisiert. Durch Photolyse der in dem so hergestellten Polymethylmethacrylat (PMMA) noch enthaltenen Polysilanketten in Gegenwart von Vinylmonomeren wie Styrol wurden Blockcopolymere erhalten. Diese wurden eingesetzt, um Blockcopolymere mit Cyclohexenoxid herzustellen. Dies geschieht durch die Bildung von an PMMA gebundenen Silylradikalen, die in Gegenwart von N-Ethoxy-2-methylpyridinium-hexafluorphosphat zu den entsprechenden Kationen oxidiert werden.

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The cationic polymerization of cyclohexene oxide (CHO), n‐butyl vinylether (BVE), N‐vinylcarbazole (NVC), and 4‐vinyl cyclohexenedioxide (4‐VCHD) is initiated upon UV irradiation (Λinc. = 350 nm) of dichloromethane solution containing N‐ethoxy‐2‐methyl‐pyridinium hexafluorophosphate (EMP+PF6) and o‐phthaldehyde. A feasible initiation mechanism involves formation of biradical by intramolecular hydrogen abstraction of triplet o‐phthaldehyde. Oxidation of these radicals by EMP+ ions yields protons capable of initiating the cationic polymerization. © 1995 John Wiley & Sons, Inc.