Two hydrogen donor-containing naphthalimide benzyl thioether photoinitiators for LED photopolymerization

This work reports two hydrogen donor-containing naphthalimide benzyl thioether photoinitiators (NBT-HD1 and NBT-HD2), combining characters of one-component and two-component photoinitiators, for LED photopolymerization. They have good absorptions at emission wavelengths of LED and their ɛmax are more than or close to 1 × 104 M−1 cm−1. Both photoinitiators can generate radicals having initiating ability through not only the cleavage of CS bonds, but also intermolecular hydrogen abstractions themselves under 405 nm LED irradiation. NBT-HD2 with acryloyl group presents an excellent capability of reducing oxygen inhibition. Moreover, NBT-HD1 or NBT-HD2/iodonium salt can trigger the cationic photopolymerization of the epoxide under 405 nm LED irradiation. More significantly, NBT-HD2 with acryloyl group exhibits a prominent migration stability in the polymer film and has broad application prospects in the field of food packaging and biomaterials. [Display omitted] •NBT-HD1 and NBT-HD2 combine characteristics of one-component Norrish I and II photoinitiators.•They can sensitize iodonium salt to initiate cationic polymerization under 405 nm LED irradiation.•They can generate radicals by CS bond cleavage and intermolecular hydrogen abstraction.•NBT-HD2 with acryloyl group can reduce oxygen inhibition and has low migration from cured film.