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 λ > 405 nm and under air.

Two new photopolymerizable vinyl (2-(allyloxy) 1,4-naphthoquinone, HNQA) and epoxy (2-(oxiran-2yl methoxy) 1,4-naphthoquinone, HNQE) photoinitiators derived from lawsone were designed in this paper. These new photoinitiators can be used as one-component photoinitiating systems for the free-radical photopolymerization of acrylate bio-based monomer without the addition of any co-initiators. As highlighted by the electron paramagnetic resonance (EPR) spin-trapping results, the formation of carbon-centered radicals from an intermolecular H abstraction reaction was evidenced and can act as initiating species. Interestingly, the introduction of iodonium salt (Iod) used as a co-initiator has led to (1) the cationic photopolymerization of epoxy monomer with high final conversions and (2) an increase of the rates of free-radical polymerization of the acrylate bio-based monomer; we also demonstrated the concomitant thiol–ene reaction and cationic photopolymerizations of a limonene 1,2 epoxide/thiol blend mixture with the HNQA/Iod photoinitiating system.

The thiol–ene photochemistry process, combined with terpenes and natural dyes, yields innovative photostimulable and bio-based materials with antibacterial properties.