Photo-curing of thick monomer systems with photoluminescent ZnO nanoparticles photoinitiators

Abstract

The photo-curing of thick monomer systems or coatings had often been limited to the depth of a few microns to few millimeters. In order to overcome this difficult problem, the ZnO nanoparticles (NPs) were researched to improve the photo-curing depth because that ZnO had the function of the photoluminescent upon the light irradiation. The light emitted by ZnO NPs penetrated into the deeper layers to increase the photo-curing depth. The best co-photoinitiator, bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide (819), in the monomer 1, 6-hexanediol diacrylate, were determined by the UV–visible spectrophotometer and fluorescence spectrophotometer. A photo-curing depth of 16.7 mm was achieved by the combination of ZnO NPs and bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide (819) in 1, 6-hexanediol diacrylate. In addition, an experimental model was proposed, the influence factors were systematically studied, and the experimental equations related to the different factors and photo-curing depths were determined by controlling the different variables. With different variables, the maximum top layer double bond conversion of 77%, and the maximum bottom layer double bond conversion of 55%. This investigation confirmed that the photoluminescent ZnO NPs had a function of improving the photo-curing depth. Therefore, this investigation provided a new idea and method for the photo-curing of thick monomer systems and coatings.