Formation of poly(methyl methacrylate)-ZnO nanoparticle quantum dot composites by dispersion polymerization in supercritical CO2

Abstract

Poly(methyl methacrylate) (PMMA)-ZnO nanoparticle quantum dot (QD) composites were synthesized by dispersion polymerization in supercritical CO2 using poly(dimethylsiloxane)-g-pyrrolidonecarboxylic acid as a stabilizer. The ZnO nanoparticle QDs were first coated with silica to improve the stability of the ZnO nanoparticles in the methyl methacrylate (MMA) monomer and supercritical CO2. Vinyl groups were then introduced onto the surface of the silica-coated ZnO nanoparticle QDs by the addition of 3-(trimethoxysilyl)propylmethacrylate (TPM). These groups helped to minimize the QD loss during the formation of the PMMA and ZnO nanoparticle QD composite. The PMMA-ZnO QD composites were dissolved into tetrahydrofuran and transparent polymeric hybrid films of ZnO nanoparticle QDs and PMMA were obtained after evaporation of the THF from the solution. The unmodified ZnO nanoparticle QDs, which were agglomerated in the PMMA matrix, and the well-dispersed silica-coated ZnO nanoparticle QDs coupled with TPM exhibited weak and high emissions, respectively under UV irradiation. The silica layer and TPM stabilized the ZnO nanoparticle QDs. TPM promotes compatibility between the QDs and the PMMA matrix.