Photosensitized cationic polymerization using allyl sulfonium salt

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 λ 380 nm in CH2Cl2 solution containing an allylic sulfonium salt, namely, 2‐ethoxycarbonyl‐2‐propenylthiophenium hexafluoroantimonate (1) (EMT+SbF6−), 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.