Low migration and high performance thioxanthone based photoinitiators

Photopolymerization technology has been limited in the application of the field of food packaging and biomedicine due to the high migration of the small molecule which are mostly from the photoinitiators. To improve migration stability of photoinitiators, polymerizable 2-vinyl thioxanthone (ETX) was synthesized by thiosalicylic acid and 4-fluorobenzaldehyde. Moreover, to further reduce the migration of photo- or cophotoinitiator, two macromolecular photoinitiators (PPI1, PPI2) were prepared by copolymerization of ETX with dimethylaminoethyl methacrylate (DMAEMA). The initiation activity of the prepared photoinitiators was studied by real-time FTIR spectroscopy. The results indicated ETX/triethanolamine (TEOA) system exhibited higher initiation performance than ITX/TEOA system by irradiation of 405 nm LED lamp, PPI2 as a one component photoinitiator displayed favorable initiation ability. In addition, the migration of ETX, PPI1 and PPI2 in the photocured film was declined obviously. ETX, PPI1 and PPI2 with low migration have potential application in the field of food package and biological materials.