Cholesteric Liquid Crystal/Carbon Fiber Thermochromic Composite Material Based on Liquid Crystal Selective Reflection

Cholesteric liquid crystals are a unique type of optical material. Some varieties of them presented different colors under temperature stimulation, with sensitive color development response and accurate temperature indication. Therefore, they attracted extensive attention in fields such as temperature display and smart textiles. However, due to the circular dichroism of cholesteric liquid crystals, which selectively reflected incident light, their color rendering effect often depended on an appropriate background. In addition, traditional liquid crystal displays usually passively regulated color through ambient temperature, making it difficult to achieve active color control. In this work, based on the analysis of the selective reflection mechanism of cholesteric liquid crystals, we used a simple scraping method to load cholesteric liquid crystals onto the surface of carbon fibers and encapsulated them with Polydimethylsiloxane (PDMS) with good hydrophobicity to prepare cholesteric liquid crystal/carbon fiber electrochromic composites (PTC). In this composite structure, the cholesteric liquid crystal endowed the carbon fiber with unique optical functions, the PDMS layer ensured the excellent durability of the liquid crystal, and the black carbon fiber effectively absorbed the excess transmitted light, further enhancing the color rendering effect. In addition, relying on the Joule heat effect of carbon fibers, PTC presented diverse color changes at different voltages and exhibited excellent cycling stability. Moreover, the active control response time of the composite material reaches 0.5 s. Its temperature–electrical coupling effect enabled PTC to demonstrate broad application potential in the fields of temperature display and smart textiles.