Abstract
The aim of this study is to examine and evaluate several dye/amine systems as photoinitiators for photopolymerization of 2-hydroxyethyl acrylate (HEA) monomer under visible light conditions. For this purpose, a series of dye/amine photoinitiators were formed using methylene blue (MB) or acridine orange (AO) as photosensitizers, and triethanolamine (TEOA), ethyl 4-(dimethylamino) benzoate (EDMAB), trioctylamine (TOA), and N,N-diméthylallylamine (DMAA) as co-initiators. The photopolymerization kinetic of the HEA monomer in the presence of proposed dye/amine systems was performed using Fourier-transform infrared spectroscopy (FTIR) analysis and the synergetic effect of the dye/amine photoinitiators systems on the photopolymerization efficiency was examined. Interestingly, (MB/EDMAB) system shows the better reactivity with a total conversion of HEA monomer.
Highlights
Visible light-activated photoinitiators (VALP’s) have received considerable attention owing to their involvement in visible light-induced polymerization
The second at 600 nm is attributed to the 0–1 vibronic transition [19, 20]. Their absorbance decreased gradually upon increasing irradiation time (Fig. 2).This decrease in absorbance is attributed to the photoreduction of methylene blue (MB) in the presence of oxygen which acts as electron donor, leading to the formation of the leuco form of dye molecules [21,22,23]
It was reported that the photobleaching of MB can be due to the presence in methylene blue of amine groups that act as electron donors in the absence of other reducing agents [10]
Summary
Visible light-activated photoinitiators (VALP’s) have received considerable attention owing to their involvement in visible light-induced polymerization. From a polymer chemistry perspective, photopolymerization using visible light offers a plethora of advantages encompassing solvent-free formulation, rapid curing at ambient temperature and appealing cost-effective bias that have led to broad application in industrial fields such as Centre de Recherche Scientifique et Technique en Analyses Physico-chimiques, BP 384, Zone Industrielle Bou‐ismail, RP 42004 Tipaza, Algeria. Laboratoire de Recherche sur les Macromolécules, Faculté des Sciences, Université de Tlemcen, BP119, 13000 Tlemcen, Algeria. TypeI photoinitiator, in which a hemolytic cleavage of its species is taking place, triggers the free radical formation and the initiation of the photopolymerization. In type II, where in the generally accepted mechanism more than two species are involved, the radicals are formed by an electron transfer reaction succeeded by hydrogen transfer between a photosensitizer (PS) and a co-initiator [6]
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