Free-standing monolayer films of ordered colloidal particles

Abstract

We report a novel method for the fabrication of large area, free standing monolayer films of close-packed colloidal particles. The method involves creating a free-standing, wet film of colloidal dispersion containing mono-dispersed hard particles (such as polystyrene or silica) mixed with smaller and softer polymer particles. During drying, hard particles present in the free standing film arrange in a hexagonal close-packed structure in a monolayer while the softer particles fill the interstices, and deform and coalesce to produce a continuous matrix around the hard particles. The deformation of the soft particles dissipates the stress generated during drying thereby preventing rupture of the monolayer film. The method is facile and very general, applicable to a large variety of colloidal particles. The monolayer films exhibit strong iridescence indicating potential application in photonic devices.