High-performance anthrone-based low-migration photoinitiators for low-power photopolymerization

Abstract

In this work, anthrone-based donor–acceptor–donor-type photoinitiators (DXD and DTD) were synthesized and introduced into a two-component system with diphenyliodonium hexafluorophosphate (Iod) for the radical photopolymerization of acrylic resin monomers. At a photoinitiator concentration of 0.5 wt%, under LED@365 nm irradiation at a power of 20 mW cm⁻², the double bond conversion of the monomer initiated by DXD and DTD was 63% and 64%, respectively, showing enhanced photoinitiation activities in comparison with 52% for a commercial photoinitiator (2-isopropylthioxine, ITX). DTD and DXD even achieved 75% and 71% conversion rates, respectively, at lower power (10 mW cm⁻²). Moreover, DXD (7%) and DTD (8%) exhibited rather lower mobility than ITX (37%) in light-curable films. Remarkably, triplet states were revealed to have an important effect on photopolymerization. The relevant mechanisms were scientifically understood by means of steady-state photolysis, fluorescence quenching, laser flash photolysis, and electron spin resonance spin trapping technologies.