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 (CLC_solid) shell is obtained after UV curing and chiral-dopant extraction. Stable CLC_solid shells are obtained when the density of the inner phase is comparable to that of the CLC shell during UV curing. The CLC_solid 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 CLC_solid shells are utilized for solvent sensors, anti-counterfeiting patches, and labeled templates for monodispersed droplets using their characteristics of differing swellings of CLC_solid shells in different organic solvents, the complexity of the R_cent, R_comm, and R_in patterns, and the pores formed in the CLC_solid after chiral-dopant extraction, respectively. Thus, CLC_solid 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.