Preparation of Flexible Liquid Crystal Films with Broadband Reflection Based on PD&SLC

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

Liquid crystals (LCs) are well known for inherent responsiveness to external stimuli, such as light, thermal, magnetic, and electric fields. Cholesteric LCs are among the most fascinating, since they possess distinctive optical properties due to the helical molecular orientation. However, the good flow, easy contamination, and poor stability of small-molecule LCs limit their further applications, and microencapsulation as one of the most effective tools can evade these disadvantages. Microencapsulation can offer shell-core structure with LCs in the core can strengthen their stability, avoiding interference with the environment while maintaining the stimuli-responsiveness and optical properties. Here, we report recent progress in the fabrication and applications of cholesteric LC microcapsules (CLCMCs). We summarize general properties and basic principles, fabrication methods including interfacial polymerization, in-situ polymerization, complex coacervation, solvent evaporation, microfluidic and polymerization of reactive mesogens, and then give a comprehensive overview of their applications in various popular domains, including smart fabrics, smart sensor, smart displays, anti-counterfeiting, information encryption, biomedicine and actuators. Finally, we discuss the currently facing challenges and the potential development directions in this field.

Temperature Self-Adaptive and Color-Adjustable Smart Window Based on Templated Cholesteric Liquid Crystals

Cholesteric liquid crystals (CLCs) exhibit selective reflection due to their self-assembled helical superstructures. Reconfigurable templates can achieve integration functions via inducing processes of molecular assemblies. Here we demonstrate temperature self-adaptive and color-adjustable smart windows using CLCs, which are fabricated via the templating method and exhibit simultaneous reflections in the visible and infrared spectra. Reflection bands formed by the refilled CLC materials can be adjusted reversibly both upon thermal and electrical actuation. In CLC with adjustable reflection in the infrared, the central wavelength of the infrared reflection band can be adjusted from 950 nm to 1305 nm via temperature, and from 1150 nm to 950 nm via electric field. A temperature variation of 10.3 °C within 55 s was induced by the single-layer templated CLC cell, and a comfortable temperature range could be effectively maintained by the CLC cell in a varied environment. In CLC with dynamic color in the visible spectrum, color shifts from 530 nm to 650 nm tuned by temperature and from 530 nm to 440 nm adjusted by electric field were obtained. Temperature-responsive reflection in the infrared spectrum contributes to automatic thermal management, and electric-field-induced band shift in the visible spectrum enables active dynamic color adjustment. The presented templated CLC smart windows show considerable potential in energy conservation and biological clock regulation fields.