A blue to red light sensitive photoinitiating systems based on 3,5-di-tert-butyl-o-benzoquinone derivatives for free radical polymerization

Abstract

New well-photobleachable initiating systems based on unsubstituted and four 6-CH2X-substituted 3,5-di-tert-butyl-o-benzoquinones (X = H, OCH3, dimethylpyrazole and benzimidazole fragments) and tertiary amines were used for photocuring different methacrylic resins under visible light irradiation. A photoreduction of these o-quinones in the presence of a series of N,N-dimethylanilines under of visible irradiation was studied. Photoinitiating properties of this series of o-benzoquinones in the presence of N,N-dimethylaniline were investigated on the example of the curing resin based on triethylene glycol dimethacrylate (TEGDMA). The photoinitiation system based on o-quinone with dimethylpyrazole fragment and N,N-dimethylaniline has the highest efficiency in this series. It was shown that the use of this initiating system allows to photocure thick layers of TEGDMA/bis-GMA (30/70 wt%) resin (0.5 cm) under the action of both LEDs with λmax 465, 520 and 630 nm. A deep photopolymerization of the composition layer (46 cm thickness) under radiation of LED@600 nm (540 mW cm−2) was carried out. The average speed of the front of photopolymerization is 2.56 cm/min.