Photoinitiability of a water-borne polysiloxane-modified benzophenone macromolecular photoinitiator

This paper reported a water-borne polysiloxane-modified benzophenone macromolecular photoinitiator (WPSHBP), whose characteristics of the photopolymerization, the migration of photolysis fragments, the volatility, and reduction of oxygen inhibition were discussed in detail. WPSHBP has a maximum absorption peak at 286 nm, and the molar extinction coefficient (ε286 nm) is 23200 M−1 cm−1. The photopolymerization rate and final double bond conversion of the system initiated by WPSHBP were enhanced with the increasing contents of triethanolamine (TEOA) and WPSHBP and irradiation intensity. WPSHBP exhibits a low migration of photolysis fragments and volatility compared with small-molecular photoinitiator benzophenone (BP). The cured films initiated by WPSHBP have good mechanical properties and thermostability compared with that by 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959). More importantly, the water-borne polysiloxane-modified photoinitiator can mitigate the oxygen inhibition in radical photopolymerization due to its enrichment on the surface of the photopolymerization system.