An anthraquinone-based oxime ester as a visible-light photoinitiator for 3D photoprinting applications

A novel anthraquinone-based oxime ester system (AQ-Ox) was successfully synthesized and used as a Type I visible-light photoinitiating system. The introduction of an anthraquinone moiety to the oxime ester group makes this system suitable for promoting photopolymerization under visible-light irradiation (LEDs@385, 405 and 455 nm) and allowed us to obtain high final acrylate conversions under laminate and air conditions in the free-radical polymerization (FRP) of an acrylate bio-based monomer. AQ-Ox also demonstrated better photoinitiating properties than commonly used Type I photoinitiators i.e. 2,2-dimethoxy-2-phenylacetophenone (DMPA) and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), and allowed the design of 3D objects by 3D photoprinting technology. This is the first example of an anthraquinone based oxime-ester used as a Type I photoinitiator for FRP at & lambda; > 405 nm and under air.