We discuss the growth and shape stabilization of small objects made of smectic and nematic liquid crystals (NLCs) in aqueous surfactant solutions. When dispersed or put in contact with an aqueous solution of CTAB, smectic A liquid crystals spontaneously grow into fibers of very uniform diameter and good optical quality, which makes them appropriate for light guiding applications. However, it is difficult to control the growth of smectic A fibers and attempts to stabilize them by photo polymerization fail to produce good quality structures for optical application. We discuss a novel method for self-shaping of nematic liquid crystal droplets into various LC fibers. The method is based on the use of two surfactants: one is dissolved in the LC and the other in the aqueous phase. By changing the temperature, the surface of the droplet increases at a fixed volume of the LC, which triggers the transformation of a droplet into fibers. This is a novel mechanism of LC droplet shape transformation, where the surface of the LC interface is controlled by the temperature and concentration of two surfactants.
Topological defects in nematic liquid crystals (NLCs) are attracting attention in recent years for generating optical vortex beams. In most cases, complex defects structures are stabilized by pre-patterned surfaces and spontaneous control with reconfigurability is not so successfully realized. Here, we use NLCs with negative dielectric anisotropy doped with a small quantity of ionic impurity confined between perfluoropolymer surfaces. Without using a template, a large number of topological defects are stabilized by the reorientation of the NLCs using an AC voltage, which is caused by a periodic density modulation of ions at the perfluoropolymer interfaces. Due to the reconfigurable property of the system, the uniform monodomain can be obtained by several methods, for example, an infrared laser and a weak shear flow. Our results offer a new approach for stabilizing multiple topological defects.
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