Acrylate photopolymer doped with ZnO nanoparticles: an interesting candidate for photo-patterning applications

Abstract

The study is devoted to the photo-patterning of photopolymers doped with dispersed ZnO quantum dots (QDs). It is checked first that ZnO QDs retain their fluorescence properties upon polymerization of the acrylate monomer mixtures. The photosensitizer (camphorquinone in our work, CQ) plays an important role in the polymerization process. Experimental and theoretical investigations are undertaken to understand the observed differences induced by the addition of a tertiary amine co-initiator species. Indeed, it is shown experimentally that in the presence of a co-initiator, when the maximum of monomer conversion is reached, the concentration of camphorquinone starts to decrease, whereas a new compound that absorbs at 390 nm is produced. It is proposed here on the basis of theoretical calculations that this species is the charge transfer complex [CQ˙⁻⋯amine˙⁺], which is stabilized in high viscous media. Then, it was shown that the addition of ZnO QDs does not modify the kinetics of polymerization but rather contributes to the enhancement of the refractive index modulation (an increase of 33% is observed) because of their spatial distribution.