Colloidal particles self-assembly in liquid crystals

Liquid crystals, being anisotropic, act as tunable solvent for the dispersion of colloidal particles. They also have shown to provide very good support for the self-assembly of particles into well- organized structures. We experimentally study the behavior of colloidal particles dispersed in liquid crystal medium. We have successfully prepared, nematic and hexagonal, lyotropic liquid crystalline phases. When dispersed into such a solvent, colloidal particles aggregate to form structures such as chains, clusters, strands, and the network of particles. Formation of these structures is driven by interaction arising from the orientation elasticity of the solvent. We used spherical Polystyrene (PS), Titanium Dioxide (TiO2), Zinc Oxide (ZnO), Silica (SiO2) and anisotropic Iron Oxides (FexOx) particles to study their behavior in liquid crystal medium.



We have studied the effect of particle concentration, size and shape on the self-assembly process. The type of liquid crystal phase and the shape of nematic liquid crystals are also shown to control the interaction between particles. Particles with size greater than1μm form small chains and cluster like structures in nematic phase while smaller particles do not show any structure formation in this system. In hexagonal phase particles with size less than 1μm shows network and strand like structures formation while larger particles do not show such structures. Effect of cooling rate on network formation was studied. We have also prepared free standing microporous structure of SiO2 nanoparticles by templating of hexagonal domain.