Polymer stabilized Monodispersed Liquid Crystal Droplets: Microfluidics Generation and Optical Analysis

Abstract

AbstractLiquid crystal droplets are widely used in optics and photonics applications. They can act as simple resonators or be arranged in interconnected periodic configurations when their external dimension are similar. In this work we optically analyze and describe the microfluidic generation of liquid crystal droplets in a thermally stabilized environment, namely water, which enables a narrow droplets diameter distribution.We demonstrate a fine control of the droplet dimensions in both nematic and isotropic phases by controlling the ratio between liquid crystal andwater flows. Droplets generated in the isotropic phase show a complex internal structure which reflects their high degree of internal disorder. Moreover, the internal configuration of the droplets also depends on the purity degree of the water in which they grow. In order to investigate their size distribution and their internal structure, a small amount of photo-polymerizable agent (NOA61 optical glue)was added to the liquid crystal to stabilize the droplets structure and to avoid their coalescence. Acting this way, polymer stabilized liquid crystal droplets were created after light induced polymerization, which are stable even after water evaporation. The polarized microscope analysis shows that the bipolar or radial order of the liquid crystal is still preserved inside the droplets depending on the water purity. Moreover an improved size uniformity is reported.