N-naphthalimide ester derivatives as Type Ⅰ photoinitiators for LED photopolymerization

In this study, a series of N-naphthalimide ester derivatives (noted NPIE1-NPIE9) with different substituents were designed as visible light photoinitiators (PIs). These structures exhibited good absorption properties in the range. Photoinitiation abilities NPIEs evaluated upon exposure to light-emitting diode at 405 nm. All demonstrated performances free radical polymerization acrylate monomers. Markedly, function conversion for monomers presence NPIE1 was higher than that benchmark PI diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO). Upon 455 nm, could also initiate effectively, i.e., photoinitiator (TPO) not efficient these long irradiation wavelengths. Through calculations N–O bond dissociation energy and excited state energy, cleavage from singlet proved be favorable. Interestingly, CO2 detected during experiments, which indicated there decarboxylation reaction irradiation. Based on obtained results, mechanism Type Ⅰ behavior can proposed. Due performance, successfully used 3D printing experiments. addition, high thermal stability found. This great improvement elaborating stable formulations.