Self-photoinitiated oligomers of water-diluted polyurethane acrylate grafted with zinc oxide of low concentrations

[Display omitted] •Novel oligomers grafted with ZnO of low concentrations can be self-photoinitiated.•The oligomers were waterborne polyurethane acrylate grafted with 0.1–0.3 wt.% ZnO.•The photoionization efficiency of the oligomers was similar to that of 2-hydroxyl-2-methyl-1-phenyl-1-propanone. In order to eliminate some problems of organic photoinitiators, self-photoinitiated oligomers of water-diluted polyurethane acrylate grafted with 0.1–0.3 wt.% zinc oxide (ZnO) were prepared. ZnO was first facilely treated by vacuum dehydration and sonication, and then reacted into the oligomers by NCO and OH groups. The oligomers were synthesized using toluene diisocyanate, polyether diols, 2, 2-dimethylol propionic acid, hydroxyl propyl acrylate, pentaerythritol triacrylate, ZnO, and triethylamine. The prepared oligomers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, particle size analyzer, and UV–vis spectroscopy. The kinetics of the UV-curing process was investigated. We observed a maximum kinetic rate constant with ZnO content of 0.2%, and the best film performance with ZnO content around 0.25%. The photoinitiation efficiency of the oligomers was similar to the value of 2-hydroxyl-2-methyl-1-phenyl-1-propanone. In general, the physical properties of the films with physically mixed ZnO were worse than those of the films with chemically grafted ZnO. This investigation demonstrated novel oligomers grafted with a few ZnO can be self-photoinitiated and facilely prepared.