Grafting of hyperbranched polymer onto the nanosilica surface and their effect on the properties of UV-curable coatings

The nanosilica is first treated with 3-mercaptopropyl trimethoxysilane (MPTMS) to introduce mercapto groups as growth points, and then hyperbranched polymer is grafted on the nanosilica surface via repeated step of thiol-ene click reaction between the acrylate double bond of trimethylolpropane triacrylate (TMPTA) and mercapto groups of trimethylolpropane tris 3-mercaptopropionate (Trithiol). FTIR results confirm that the grafting procedure is feasible, and TGA results indicate the grafting ratio is as high as 45.0 %. The curing kinetic, monitored by photo-DSC, shows that both terminal acrylate double bonds and mercapto groups can accelerate the curing speed of the UV-curing organic-inorganic hybrid coatings. The mechanical and physical properties of UV-curable hybrid coatings containing modified nanosilica at different generations are also investigated.