Silicone-Thioxanthone: A Multifunctionalized Visible Light Photoinitiator with an Ability to Modify the Cured Polymers

A silicone-thioxanthone (STX) visible light photoinitiator was prepared by the nucleophilic substitution reaction of 2-[(4-hydroxybenzyl)-(methyl)-amino]-9H-thioxanthen-9-one (TX-HB) and γ-chloropropylmethylpolysiloxane-co-dimethyl-polysiloxane (PSO-Cl). Its structure was confirmed by (1)H NMR, (13)C NMR, FTIR, UV-vis and GPC. The photopolymerization kinetics of 1, 6-Hexanedioldiacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA) initiated by STX confirmed that STX is an efficient photoinitiator. Its visible light photolysis experiment and the photopolymerization kinetics studies implied that a possible synergistic effect existed between two adjacent thioxanthone groups. Moreover, a higher migration stability was revealed in STX than 2-benzyl (methyl) amino-9H-thioxanthen-9-one (TX-B). STX could change the surface property of the cured film of polyurethane diacrylate prepolymer (PUA) from hydrophilic to hydrophobic, as well as change the thermal stability of the polymer network. Meanwhile, it could improve the resistance against water and acid. Thus, STX is an effective multifunctionalized photoinitiator.