Synthesis and free radical photopolymerization of one-component type II photoinitiator based on benzophenone segment

• Benzophenone derivatives had been prepared and examined as one-component Type II photoinitiators for free radical photopolymerization. • Better light harvesting and thermal stable of the photoinitiators are achieved. • New photoinitiators capable increased the rate of photopolymerization upon UV and 405@LED lamp. In this study, novel visible light one-component photoinitiators ( BPN-D , BPN-Ph , BPN-N , BPN-An and BPN-Py ), based on benzophenone scaffold have been synthesized. Compared to the reference samples (BPN and EMK), these new photoinitiators not only contribute to red-shifted UV–Vis absorption regions but also strongly enhance the thermal properties. The free radical generation in one-component Type II photoinitiators were also confirmed by the electron spin resonance (ESR) and steady-state photolysis techniques, and their chemical reaction mechanisms were also discussed. Finally, a photopolymerization studied using those novel and reference photoinitiators as one-component Type II photoinitiator was performed. The photopolymerization of TMPTMA monomer initiated by various photoinitiators was monitored by photo-DSC experiment. Under UV lamp irradiation, the BPN-Ph compound could be promoted with the highest double bond conversion efficiency up to 30%, which was higher than the reference BPN (25%) and EMK (22%) based photoinitiating systems. In addition, the BPN-An based formulation exhibited highest double conversion efficiency (22%) upon LED@405 nm. The experimental results show that the synthesized compounds can effectively improve photosensitivity as well as enhanced their optical and thermal properties.