Light-induced assembly of tailored droplet arrays in nematic emulsions

Dynamic manipulation of droplets could be achieved by light in a nematic liquid crystal (LC) doped with photochromic azobenzene derivatives. On irradiation of ultraviolet light, the trans→cis photoisomerization drives a directional motion of the droplets towards the cis-rich region and assembled close-packed two-dimensional hexagonal colloidal crystals. This behavior is mainly attributable to the reduction of the droplet-LC interfacial tension, associated with the enhanced surface activity of cis isomers. We also performed photochemical assembly of tailored droplet arrays by projection of computer-generated images on the samples. The photoinduced manipulation of droplets will provide a versatile approach to microstructuring of LC devices.

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