Abstract
A review of our work on two- and-three component photoinitiator systems is presented. The emphasis is in on visible light polymerization in aqueous media. The systems discussed comprise a synthetic dye as sensitizer and an onium salt as coinitiator, or a dye-amine-onium salt with the amine as coinitiator and the onium salt as an enhancer of the polymerization efficiency. The effect of the composition of the system on the photopolymerization kinetics was analyzed. To this end, the photophysics and photochemistry of the dye under polymerization conditions was explored by means of stationary and time-resolved spectroscopic methods. Different dyes and onium salts were investigated. The action mechanism of the different photoinitiators systems is discussed.
Highlights
The development of new materials by means of photopolymerization requires investigations aimed at discovering more efficient photoinitiator systems
Studies have been reported on ammonium salts [2], phosphonium [3], sulfonium [4], and iodonium salts [5] with aryl and/or alkyl groups on its structure
In a previous paper [28], we have investigated the interaction of diphenyliodonium cation (DPI+) with the excited singlet and triplet states of eight polycyclic aromatic hydrocarbons in acetonitrile solution
Summary
The development of new materials by means of photopolymerization requires investigations aimed at discovering more efficient photoinitiator systems. Electron transfer and/or energy transfer from the excited PAH to the iodonium cation were suggested as the first reaction step in the initiation mechanism In some cases, it is not clear whether the singlet or triplet excited state of the sensitizer is responsible for the interaction with the onium salt [24, 26, 27]. In a previous paper [28], we have investigated the interaction of diphenyliodonium cation (DPI+) with the excited singlet and triplet states of eight polycyclic aromatic hydrocarbons in acetonitrile solution These results confirmed the electron transfer nature of the quenching process:. The experimental details are given elsewhere [31,32,33,34]
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