Design of Transparent Hybrid Materials Using ZrO₂ Nano-Particles as Multivinyl Crosslinking Agent

Abstract

A novel surface treatment method of ZrO₂ nanoparticles with 8 nm in a diameter and their hybridization with polymers have been studied to prepare the transparent organic－inorganic nano-hybrid materials. The surface treatment was achieved by direct transfer of ZrO₂ nanoparticles from aqueous phase to toluene phase without any coagulation. The method was successfully attained by adding small amount of carboxylic acid as the surface treatment agent, toluene, and methanol to ZrO₂ aqueous dispersion, followed by successive evaporations and solvent replacements to toluene dispersion. Transparent ZrO₂ toluene dispersion was obtained, when adding the carboxylic acids with the number of carbon atom higher than 4. The surface modified ZrO₂ particles were nano-dispersible into several organic solvents and vinyl monomers to afford transparent solutions. Methacrylate-functionalized ZrO₂ nano-particles were copolymerized with styrene or methyl methacrylate to produce optically transparent thermosetting nano-composite materials with a refractive index much higher than the original polymer. The network structures produced by copolymerization of vinyl monomer with methacrylate-functionalized ZrO₂ nano-particles as multivinyl crosslinking agent play an important role to prevent the coagulation of ZrO₂ particles.