Improving ZnO photoinitiation efficiency by surface reaction with 2-hydroxy-2-methylpropiophenone

[Display omitted] •ZnO particles reacted with 2-hydroxy-2-methylpropiophenone.•An inorganic-organic hybrid ZnO photoinitiator was prepared.•The photoinitiation conversion and efficiency of ZnO particles were improved.•An easy method to upgrade large ZnO particles to be efficient photoinitiators. ZnO was used as an inorganic photoinitiator in polymeric materials to reduce the pollutions of organic photoinitiators and their photolysis fragments. However, the ZnO photoinitiator suffered low monomer conversions and efficiencies. Therefore, a novel inorganic-organic hybrid ZnO photoinitiator (ZnO-TDI-1173) was prepared by the surface reaction of ZnO, on which OH groups reacted with one NCO group of toluene diisocyanate and then another NCO group reacted with 2-hydroxy-2-methylpropiophenone. The FTIR, scanning electron microscope, thermogravimetric analysis, and X-ray diffraction were characterized and proved the successful surface modification. The photoinitiated polymerization kinetics of ZnO-TDI-1173 in methyl methacrylate were studied. When the UV irradiation time was 220 s, the methyl methacrylate conversion with ZnO-TDI-1173 reached 32.14%, which was bigger than 18.26% of ZnO. This investigation demonstrated an improved photoinitiation efficiency of ZnO-TDI-1173 in comparison with that of ZnO, facilitating a new and easy method to upgrade the large ZnO powder to be an efficient photoinitiator.