Thioxanthone based one-component polymerizable visible light photoinitiator for free radical polymerization

Abstract

A thioxanthone based one-component polymerizable visible light photoinitiator with a high photopolymerization activity and very good migration stability was designed and prepared.

High‐Performance and Low Migration One‐Component Thioxanthone Visible Light Photoinitiators

“…Photolysis experiments of TX‐EA and TX‐BDA were performed upon visible light exposure in the absence of hydrogen donors by UV–visible spectrometer (Figure ). The photolysis of TX‐PA in THF has been studied in our recent report . As seen from Figure , all of them degraded after visible light irradiation as expected.…”

“…As shown in Scheme , upon visible light exposure, TX‐BDA could yield aminoalkyl active radicals. Aminoalkyl radicals are priority to transfer to acryloxy in TX‐BDA rather than monomers since they are so close to the active free radicals . The stable six‐number ring or eight‐number ring radicals came into being through the radical transfer.…”

“…As an important Type II photoinitiator, thioxanthone (TX) was used in the construction of polymerizable photoinitiator systems, but most of them were UV‐sensitive photoinitiators. Our research aims to construct the thioxanthone based visible light photoinitiating systems for radical polymerization . For aforementioned purpose, a polymerizable one‐component visible light photoinitiator 4‐((methyl(9‐oxo‐9H‐thioxanthen‐2‐yl)amino)methyl)phenyl acrylate (TX‐PA) (Figure ) has been studied .…”

One‐component, double‐chromophoric thioxanthone photoinitiators for free radical polymerization

“…Photochemically triggered bond cleavage in Type‐I initiators occurs typically at high energy. For this reason, Type‐I photoinitiators show often a strong absorption band in the UV region of the electromagnetic spectrum . This short wavelength absorption characteristic, however stands in contrast to the current trend in industrial production, where expensive UV light sources are more and more replaced by cheaper visible light LEDs.…”

Naphthoylenebenzimidazolone dyes as one‐component photoinitiators

“…In the last decade many papers have described the synthesis of initiators. Only thioxanthone [3][4][5][6][7][8][9], benzophenone [10][11][12][13][14][15][16], erythrosine B [17], and, more recently, naphthoquinone [18] and benz[cd]indol-2(1H)-one [19] linked with appropriate groups have been applied as chromophores to obtain one-component initiator systems. There are two different ways to create initiators sensitive to visible radiation.…”