Templated droplets and ordered arrays in polymer-dispersed liquid-crystal films

Well-ordered two-dimensional hexagonal arrays of micrometer-sized nematic liquid-crystal droplets are prepared in polymer films. Droplets of uniform sizes and shapes are formed by prefabricating the voids in which the liquid crystal is to be entrapped. Void preparation involves deposition of polystyrene microspheres on a substrate to form a colloidal crystal array. The array is coated with water-soluble polymer and dried. The microspheres were then extracted with organic solvent. The voids are refilled with liquid crystal by capillary filling. The materials are characterized throughout this process by atomic force and multiphoton-excited fluorescence microscopies. Polarization-dependent fluorescence images show well-ordered nematic configurations within each droplet. Surprisingly, the nematic alignment in neighboring droplets is often found to be correlated over large domains spanning several droplets. The origins of these organizational correlations are explored.