Acylphosphine oxide photoinitiators containing Si with sulfhydryl bridge linkages

Two novel small-molecule acylphosphine oxide photoinitiators incorporating organosilicon, named TPO-Si and TPO-L-Si, have been synthesized using the commercial photoinitiators 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) and 2,4-trimethylbenzoylphenylphosphonate (TPO-L). TPO-Si and TPO-L-Si optical characteristics were studied using steady-state photolysis, electron paramagnetic resonance measurements, and UV-visible absorption spectroscopy. Although the photopolymerization efficiency of TPO-Si and TPO-L-Si is slightly lower than that of TPO and TPO-L, they exhibit higher compatibility with methyl methacrylate-based polydimethylsiloxane (MTQ-570), as indicated by photopolymerization experiments. Furthermore, TPO-Si and TPOL-Si exhibit greater thermal and migratory stability, and the cured films produced by TPO-Si and TPO-L-Si are more hydrophobic.