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

Abstract

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-1-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 (1H NMR), 13C NMR, 29Si 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.