Some photoinitiated polymerisations and related reactions
A description of the absorption of light by organic molecules and the ways by which the energy gained can be lost by the excited compounds has been presented. The Stern-Volmer equation has also been described. Free radical photoinitiation of polymerisation has been reviewed. An investigation has been carried out of ketone / amine photoinitiation of polymerisation of thin film and bulk polmerisations of acrylate esters. The photoreduction and photooxygenation of the amines used in the polymerisations, dimorpholinoalkanes N,N,N,N-tetraethyldiaminoalkanes and others have been carried out in an attempt to rationalise the observations made in the polymerisation experiments. The dehalogenation of aryl halides has been described. The photolysis of [special character omitted]-(4-halophenoxy)alkyl bromides and [special character omitted]-phenoxyalkyl halides has been carried out and evidence presented for the nature of the excited state responsible for reaction. Criteria for the intervention of radical ions in the photoreactions of aromatic halides with triethylamine have been given and where appropriate evidence for the intermediacy of such species has been presented. The photo-Claisen rearrangement has been studied and the effect of hydrogen bromide on the reaction investigated. The photoinitiation of cationic polymerisation by sulphonium and iodonium salts has been reviewed and a study carried out of thin film polymerisations in printing inks. The photochemistry of triaryl-sulphonium, thioxanthylium and diaryliodonium salts in methanol have been examined and a mechanism proposed for the decomposition. The photosensitization of photoinitiated cationic polymerisation has been investigated and Stern-Volmer plots recorded of the quenching of their fluorescence by cationic photoinitiators carried out.