(298c) Liquid Crystal Emulsions Stabilized By Nanoparticle-Surfactant Complexes

Past studies have reported that confinement of liquid crystals (LCs) within micrometer-sized droplets dispersed in aqueous phases (e.g., LC-in-water emulsions) provides a versatile platform for the design of droplet-based LC sensors that can respond sensitively to the presence of amphiphilic analytes in aqueous environments. Here, we report a novel approach to design responsive materials based on LC emulsions with improved colloidal stability. Our approach makes use of surfactant-nanoparticle complexes (C_nTAB/SiO₂, n=8,12,16) that adsorb to the LC droplet interface to stabilize LC emulsions for extended periods. The LC droplet size remains largely unchanged over time (e.g., droplet diameter ≤ 4 μm over 3 months), and droplets that sediment over this time period can be readily dispersed, demonstrating the remarkable colloidal stability of the system. Moreover, the addition of amphiphiles (e.g., SDS) to these C_nTAB/SiO₂-stabilized LC emulsions triggers bipolar-to-radial changes in LC droplet configurations similar to those observed in bare LC emulsions that can be readily observed using polarized light. Overall, our results suggest that LC emulsions stabilized by C_nTAB/SiO₂ complexes provide a potential approach to design liquid-droplet sensors with improved colloidal stability for the detection of aqueous analytes.