Experimental Insight into Thermally Driven Structural Evolution and Metastable Dynamics of Cholesteric Liquid Crystal Droplets.

Understanding the thermo-responsive behavior of confined liquid crystals is essential for advancing their use in functional photonic devices. In this study, the temperature-driven phase transitions, molecular arrangements, and intermediate structural states of cholesteric liquid crystals (CLCs) confined within microdroplets are investigated. Monodispersed CLC droplets exhibiting a stable radial-spherical-structure (RSS) are fabricated via microfluidics to explore continuous transitions between highly ordered helical architectures and disordered isotropic phases. During heating, localized distortions appear within the concentric-ring pattern of the RSS texture, followed by ordered domains shrinking as the CLC becomes isotropic. This behavior could be mainly attributed to the fact that the system overcomes the free-energy barrier stabilizing the RSS configuration once the temperature is raised to 54 °C. Interestingly, the change process of CLC during cooling is not entirely the reverse process of the heating process. The "radical" multidomain and the blue phase-like texture are sequentially formed during the process from isotropic to cholesteric. Furthermore, faster cooling rates directly increase nucleation density and accelerate tactoid growth. In addition, the elimination of tactoid boundaries during nucleation and self-assembly enables the formation of large aggregates, which ultimately relax back to the stable RSS configuration driven by overall free-energy minimization. These experimental insights into the spatially confined self-assembly and thermo-responsive kinetics of CLCs provide a critical foundation for advancing their application in sensing, displays, and functional photonic devices.