Bistable Color‐Tunable Liquid Crystal Fiber by the Method of Mechanical Drawing with Synchronous Ultraviolet Polymerization

Abstract

A color‐tunable fiber is demonstrated to reflect colors by switching the electric field on a chiral liquid crystal (CLC) with different helical twisting powers. With the purpose of bistability and low power consumption, the mechanism of the CLC fiber proposed in this study is an electric‐field‐induced phase change. To maintain the balance of wearable flexibility and mechanical stability, the liquid crystal fiber is constructed by the method of mechanical drawing with synchronous ultraviolet polymerization. To be a typical 1D structure, the central core of the CLC fiber is made of an aluminum wire, which is used to load the driving voltage as well as a mechanical support. In addition, there are three claddings surrounding the central core: the color‐tunable cladding filling with CLC material, the polymer cladding to anchor the liquid crystal, and the outer transparent electrode cladding. Bistable color change is realized by switching two given voltages corresponding to the planar state (P‐state) and focal conic state (FC‐state). Furthermore, to knit N fibers together, 2N colors can be realized by applying electric voltages to the fiber bundle.

Research Progress of Electrically Driven Multi-Stable Cholesteric Liquid Crystals

“…Multi-stable cholesteric liquid crystal devices have been continuously developed and optimized. They exhibit increasingly excellent electronic control optical performance and can be applied in multiple fields such as smart windows, handwriting boards, liquid crystal fibers, and light valves [ 24 , 86 , 87 , 88 , 89 ].…”

“…In addition to smart windows, devices are often used in the fields of handwriting boards and liquid crystal fibers [ 87 , 88 , 89 ]. The reflection wavelength of cholesteric liquid crystal in handwriting boards is in the visible light region.…”

“…Wang et al reported a color-tunable liquid crystal fiber, which was constructed by mechanical stretching and UV polymerization with good thermal and mechanical stability. Under the stimulation of an electric field, the liquid crystal fiber has three states, and the fiber has considerable potential for applications in the fields of color-tunable clothing, flexible smart fabrics, and military camouflage [ 89 ]. In addition to the above two fields, tri-stable devices can also be applied in the field of gratings.…”

“…Notably, planar texture can be used as a glare reduction mode due to the dye's enhanced absorption of incident light. At the same time, the author introduced the color-changing ability into the device by controlling the cholesteric liquid crystals pitch within the wavelength range of visible light and demonstrated a color-tunable glass, as shown in Figure 16b In addition to smart windows, devices are often used in the fields of handwriting boards and liquid crystal fibers [87][88][89]. The reflection wavelength of cholesteric liquid crystal in handwriting boards is in the visible light region.…”

“…Xing et al studied the dynamics of the switching process of liquid crystal grating by digitally processing recorded image sequences and reported a tunable liquid crystal grating [90]. In addition to smart windows, devices are often used in the fields of handwriting boards and liquid crystal fibers [87][88][89]. The reflection wavelength of cholesteric liquid crystal in handwriting boards is in the visible light region.…”