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    可拉伸胆甾相液晶弹性体的图案化及力致变色

    Patterning and Mechanochromism of Stretchable Cholesteric Liquid Crystal Elastomers

    • 摘要: 胆甾相液晶弹性体(CLCE)是一种具有周期性螺旋结构的光子晶体材料,兼具光学各向异性和力致变色特性,在柔性光子器件等领域前景广阔,然而,制备图案化CLCE仍面临挑战。本文基于巯基-迈克尔加成反应,合成了聚合度可控、不同链长的温敏变色胆甾相液晶齐聚物(CLCO),系统探索了其液晶相结构与结构色之间的构效关系。利用温度诱导胆甾相-近晶相的相转变效应,实现CLCO结构色覆盖红、绿、蓝三原色区间(波长变化范围(Δλ)为126 nm);在不同温度下通过局部光聚合制备了图案化的可拉伸CLCE;通过降低液晶单体及手性掺杂剂中丙烯酸酯基团与硫醇扩链剂中巯基的物质的量之比(n(Acrylate)/n(Thiol)),可以提高CLCO的聚合度,并降低CLCE的交联密度,使其断裂伸长率提升至200%,力致变色范围覆盖可见光区。本文不仅为CLCE的结构色动态调控与图案化提供了新思路,还为其在信息加密、防伪等领域的应用奠定了材料基础。

       

      Abstract: Cholesteric liquid crystal elastomer (CLCE) is a photonic crystal material with a periodic helical structure that combines unique optical anisotropy with mechanical stimulus-responsive properties, demonstrating broad application prospects in flexible photonic devices. However, the preparation of patterned CLCE still faces challenges. Based on the thiol-Michael addition reaction, thermochromic cholesteric liquid crystalline oligomers (CLCO) with controllable degrees of polymerization and varying chain lengths were synthesized, and the structure-property relationship between their liquid crystal phase structure and structural color was systematically explored. Utilizing the temperature-induced cholesteric-smectic phase transition effect, the structural color of CLCO can be tuned to cover the three primary colors, red, green, and blue, within a wavelength range (Δλ) of 126 nm. Patterned stretchable CLCE films were prepared through local photopolymerization at different temperatures. By further decreasing n(Acrylate)/n(Thiol), the degree of polymerization of CLCO was enhanced and the crosslinking density of CLCE was reduced, resulting in an increase in its elongation at break to 200% and enabling force-induced color changes across the visible spectrum. This study not only provides new insights into the dynamic regulation and patterning of structural color in CLCE, but also establishes a material foundation for applications in information encryption and anti-counterfeiting.

       

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