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Polymerizable and polymeric type I and type II photoinitiators. Volume 2

Lewis, S.P. (1992). Polymerizable and polymeric type I and type II photoinitiators. Volume 2. (Unpublished Doctoral thesis, City, University of London)

Abstract

A number of monomeric and polymeric benzil and benzoin derivatives were prepared and were evaluated as photoinitiators for the polymerization of vinyl monomers. Some of the benzoin derivatives were designed such as to exhibit water compatibility, and were evaluated in aqueous media.

The mode of photodecomposition of the polymeric photoinitiators was determined by radical trapping experiments, and a chain transfer agent was employed to control their molecular weights. In all cases, the performance of the polymeric photoinitiators was compared to that of a monomeric analogue, in order to determine the effects on efficiency of incorporation of the photoreactive groups into a polymeric system. For all of the photoinitiators evaluated in this manner, it was observed that incorporation into a polymeric network - whether as pendant groups or as a part of the polymer backbone - led to an enhancement of efficiency. Reasons for this observation are suggested in the text.

All of the monomeric photoinitiators prepared carried substituents at the 4 and 4 ’ positions, which would enable them to be built into a polymer chain. Comparisons were made between the efficiencies of the various monomeric systems, in order to observe any effect which the substituents may have had on performance. In all cases, evaluations were carried out in both the presence and absence of a tertiary amine synergist. It was generally observed that the presence of electron-donating substituents at the 4 and 4’ positions led to an increase in photoinitiating efficiency.

The relative efficiencies of the photoinitiators in the initiation of vinyl polymerizations were evaluated by two or more of the following methods: solution polymerization, thin film UV curing and real-time infrared spectroscopy.

Publication Type: Thesis (Doctoral)
Subjects: Q Science > QD Chemistry
Departments: School of Science & Technology
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