Initiating gradient photopolymerization and migration of a novel polymerizable polysiloxane α-hydroxy alkylphenones photoinitiator

This paper reported a photocleavage type polymerizable organosilicon macromolecular photoinitiator (HHMP-Si-CC), which was synthesized based on traditional photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl propan-l-one (HHMP) and amino polysiloxane. HHMP-Si-CC cannot only spontaneously form a concentration gradient in the photopolymerization system, initiate gradient photopolymerization and effectively mitigate inhibition of oxygen, but also overcome the migration of photolysis fragments of the photoinitiator from UV-curable material. Its structure was confirmed by proton nuclear magnetic resonance (H-1 NMR), C-13 NMR, Si-29 NMR and Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The kinetics of photopolymerization of HHMP-Si-CC was studied by real-time infrared spectroscopy (RTIR). Moreover, it was proved by X-ray photoelectron spectroscopy (XPS) and UV absorption that HHMP-Si-CC had relatively good self-floating ability. The polymer initiated by HHMP-Si-CC presented a gradient change in the degree of polymerization, molecular weight, thermostability and glass transition temperature (Tg). The surface morphology of poly(triethylene glycol diacrylate) (PTPGDA) initiated by HHMP-Si-CC was studied by scanning electron microscopy (SEM). More importantly, the migration of photolysis fragments of the HHMP-Si-CC from UV-curable materials was also investigated by high performance liquid chromatography (HPLC). The results showed that the migration more was effectively mitigated by introducing polymerizable groups into the HHMP-Si-CC. HHMP-Si-CC should have potential applications for preparing more environmentally friendly gradient materials. (C) 2014 Elsevier Ltd. All rights reserved.