Naphthyl-based acylphosphine oxide photoinitiators with high effiency and low migration

A series of new naphthyl-based acylphosphine oxides (N1–N3) have been designed and synthesized. The obtained compounds could be used in the photo-initiated free radical polymerization (FRP). The performances of N1–N3 in the FRP of trimethylolpropane triacrylate (TMPTA) and their UV–vis spectra were evaluated and compared with 2,4,6-trimethyl(phenyl)diphenyl oxide (TPO, a commercial photoinitiator). Results showed that N1–N3 possessed higher molar absorption coefficients and wider absorption wavelength than TPO. Under the same reaction conditions, N3 exhibited the best double bond conversion (DC) of TMPTA in the tested photoinitiators. Moreover, the calculated migration of N1–N3 of the solidified samples was 1/7, 1/3 and 1/23 of TPO, indicating the lower migration properties. Possible reasons of the performance of N1∼N3 were proposed.