Reaction mechanisms triplet-state hydrogen atom transfer

In this mechanism the excitation of the sensitizer by the absorption of light produces the exclted singlet state from which the photochemlcally reactive n-ir triplet state Is formed by Intersystem crossing. This triplet state abstracts a hydrogen atom from the thiol molecule and forms a ketyl radical and a thlyl radical. The ketyl radicals dimerize to plnacols and the thlyl radicals add to the polymer by a chain mechanism. The ketyl radicals may also Initiate and terminate chains either by direct reaction and/or by hydrogen transfer. The preferred ene compounds are those having the allyllc structure because of their Inherent chemical stability (38). 

---