Optical Properties and Applications of Photonic Shells

Uniformly sized cholesteric liquid crystal (CLC) shells are fabricated from a reactive CLC mesogen mixture via a microfluidic method with a fine-tuned density of the inner phase of the CLC shell by controlling the mixing ratio of glycerol and water. The solid-state CLC (CLCsolid) shell is obtained after UV curing and chiral-dopant extraction. Stable CLCsolid shells are obtained when the density of the inner phase is comparable to that of the CLC shell during UV curing. The CLCsolid shells display three modes of reflection patterns: central reflection (R-cent), cross-communications among adjacent CLC shells (R-comm), and reflection within the shell interior (R-in). The three different modes of reflection of the CLCsolid shells are utilized for solvent sensors, anti-counterfeiting patches, and labeled templates for monodispersed droplets using their characteristics of differing swellings of CLCsolid shells in different organic solvents, the complexity of the R-cent, R-comm, and R-in patterns, and the pores formed in the CLCsolid after chiral-dopant extraction, respectively. Thus, CLCsolid shells have intriguing photonic properties and can be applied in many different fields, which have previously not been explored with liquid crystal-state CLC shells.