Photonic materials from self-assembly of "tolerant" core-shell coated colloids

The self-assembly of core-shell colloids into ordered arrays holds promise as a convenient method for the fabrication of photonic opals or as templates for inverse opaline materials. Recent advances in the layer-by-layer (LbL) technique for coating colloids have made it possible to create composite core-shell materials with exquisite control over the thickness and chemical composition of the shell. Here, we demonstrate that modification of the outer surface of the LbL-coated colloids by grafting a brush layer (comprising a water-soluble poly(ethylene oxide) copolymer) renders them highly "tolerant" to the formation of ordered opals. Ordered assemblies with long-range spatial order are readily formed by drying such surface-modified coated colloids in a flow cell that we have specially designed to construct films with a defined thickness. We demonstrate the assembly of films from brush-modified polyelectrolyte-coated colloids and their characterization using electron microscopy and transmission optical spectroscopy.