Supramolecular diaryliodonium salt-crown ether complexes as cationic photoinitiators

摘要

It is known that during photoinitiated cationic ring opening polymerisation of alkyl glycidyl ethers with iodonium and sulphonium salt photoinitiators, a metastable protonic acid-monomer complex is formed, which is believed to be the cause of an induction period. The presence of multifunctional glycidyl ether monomers, which can provide multidentate coordination, can lead to longer induction periods. Addition of small amounts of crown ethers to epoxy formulations can also lead to retardation of photopolymerisation.