Self-organization of colloids in confining geometries with mobile interface

Abstract

Complex systems of colloidal particles and emulsion droplets or bubbles have been studied intensively due to non-conventional rheological behavior and practical applications ranging from cosmetics and drugs to flotation of mineral ores. Recent advances in microfluidics have enabled to make emulsion droplets or bubbles in precisely controlled manner and more elaborate drop manipulation techniques are still being developed. Along with recent development of programmatic microfluidics, self-organization of colloidal particles confined in emulsion droplets has attracted great attentions. Depending on the surface properties, size and concentration of the colloidal particles, the emulsion droplets can confine the colloids within three dimensional (3D) space of the drop volume or 2D planar space of the drop surface. Here, I deal with various complex systems of emulsion droplets and colloidal particles for preparation of advanced functional materials especially for photonic applications and elaborate study of related physics and chemistry. In advance to the detailed studies of complex systems, colloidal crystallization in bulk or confined geometries is briefly discussed in introduction part. Especially, preparation methods of emulsion droplets and their confining effects for spherical assemblies are explained. In addition, interaction between colloidal particles and electromagnetic waves are followed in introduction part. 3D confinement of colloidal particles in monodisperse emulsion droplets induces compact spherical assemblies with identical size and structure after evaporation of droplet phase. Especially, for submicron-sized particles, the assemblies show photonic bandgap due to the periodic modulation of dielectric constant. Here, what we should notice is that the assemblies have isotropic photonic property due to the spherical symmetry unlike conventional film-type assemblies. The detailed fabrication process and properties of photonic crystals in spherical sh...