Hollow Cholesteric Liquid Crystal Elastomer Fiber with Synergistically Enhanced Resilience and Mechanochromic...

Mechanochromic cholesteric liquid crystal elastomer (CLCE) are unique anisotropic rubbers with programmable optical properties in response to external stimuli, bringing considerable interest in display, sensing, and smart textiles. However, creating mechanochromic CLCE fibers with high sensitivity, excellent resilience, and stable color-changing reversibility is still a challenge. This work describes mechanochromic CLCE symmetric hollow fibers with excellent radial helix alignment prepared by solvent evaporation-induced assembly and template assistance. The cylindrical symmetry renders the response identical in all directions perpendicular to the fiber axis. The hollow fibers show mechanochromic ability in the full visible spectrum, a large wavelength blueshift of 2.25 nm·%^-1 under low strain. Excellent mechanochromic reversibility of 100 cycles and resilience are both devoted by cross-linking structure in the wall layer, which also contributes to reversible orientation-recovery of liquid crystal units during stretching-recovery cycles. Numerical models and experimental measurements demonstrate the hollow structure enabled fibers to produce air pressure inside when being stretched, and the fiber wall layer is subjected to greater stress compared to solid fibers, thus achieving high mechanochromic sensitivity. In addition, hollow fiber can still change color when subjected to the expansion stress inside the cavity, and programmable information display in fabric prolongs its application in intelligent textiles.