Fabrication of Particle-arrayed Poly(methyl methacrylate) Films from Colloidal Crystals Formed in Organic Solvent

Abstract

Colloidal crystallization of polymer-modified silica in organic solvent and incorporation of the colloid crystals into polymer matrix were investigated. Colloidal crystallization of Polymer-grafted silica, of 136 nm diameter, was observed in organic solvents, which were polar and good ones for modified polymer. The crystallization was confirmed to occur due to the electrostatic repulsion between the modified silica in the suspension. Neighboring inter-particle distances in the colloidal crystals were fairly longer than length of grafted polymer chains. Colloidal crystals formed by polymer-grafted silica particles were immobilized by a step-wise procedure consisting of gelation by radical copolymerization followed by solidification by further polymerization. In the first step, the poly(methyl methacrylate)-grafted silica colloidal crystal suspension was successfully incorporated into the gel by copolymerization of methyl methacrylate (MMA) and 1,2-dimethylacryloyloxyethane (DME). The second radical polymerization of MMA or trifluoroethyl methacrylate (TFEMA) was performed after substituting the solvent with each monomer. By this two-step procedure, the silica particle array of colloidal crystals was immobilized to make into durable material.