Hussain Saddam, Park Soo-Young
School of Applied Chemical Engineering, Polymeric Nano Materials Laboratory, Kyungpook National University, Daegu 41566, Republic of Korea.
ACS Appl Mater Interfaces. 2021 Dec 15;13(49):59275-59287. doi: 10.1021/acsami.1c18697. Epub 2021 Dec 2.
The unique combination of the rubber-like property and the photonic helicoidal structure of cholesteric liquid-crystal elastomers (CLCEs) results in one-handed circular polarized light reflection, the wavelength of which is dictated by the Bragg relationship. Herein, a highly stretchable mechanochromic photonic CLCE film was fabricated by cross-linking mesogenic oligomers having thiol terminal groups, which further reacted to form disulfide (-S-S-) linkages. The mechanically stretched photonic CLCE film reflected both right- and left-handed circular polarized lights with a blue-shifted color. The helicoidal pitch and handedness controlled by the applied strain were programmed through a dynamic exchange reaction between the -S-S- linkages, thus realizing the patterning at selective regions. The pattern almost vanished under unpolarized daylight but was visible under circularly polarized light when the patterned photonic CLCE film had been heated above its isotropic temperature. The hidden patterns of the heat-treated CLCE film reappeared under unpolarized daylight when stretched, demonstrating a data encryption ability. These patterned photonic elastomers can be uniquely used in sensors, actuators, soft robotics, flexible displays, data encryption, and anticounterfeiting applications with a mechanochromic camouflage response.
胆甾相液晶弹性体(CLCEs)的橡胶状特性与光子螺旋结构的独特结合导致了单手圆偏振光反射,其波长由布拉格关系决定。在此,通过交联具有硫醇端基的介晶低聚物制备了一种高度可拉伸的机械变色光子CLCE薄膜,该低聚物进一步反应形成二硫键(-S-S-)。机械拉伸的光子CLCE薄膜反射左旋和右旋圆偏振光,颜色发生蓝移。通过-S-S-键之间的动态交换反应,对由施加应变控制的螺旋节距和旋向进行编程,从而在选定区域实现图案化。当图案化的光子CLCE薄膜加热到其各向同性温度以上时,图案在非偏振日光下几乎消失,但在圆偏振光下可见。拉伸时,热处理后的CLCE薄膜的隐藏图案在非偏振日光下重新出现,展示了数据加密能力。这些图案化的光子弹性体可独特地用于具有机械变色伪装响应的传感器、致动器、软体机器人、柔性显示器、数据加密和防伪应用。