Department of Materials Physics and Chemistry, School of Materials Science and Engineering , University of Science and Technology Beijing , Beijing 100083 , China.
CAS Key Laboratory of Bio-Inspired Materials and Interfaces Sciences, Technical Institute of Physics and Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.
ACS Appl Mater Interfaces. 2019 Dec 11;11(49):46124-46131. doi: 10.1021/acsami.9b14202. Epub 2019 Nov 22.
Photonic shape memory (SM) polymers based on liquid crystalline blue phase (BP) films have been fabricated by self-assembly and subsequent photopolymerization of liquid-crystal mixtures. These freestanding BP films exhibit narrow photonic band gaps and high reflectivity in the visible wavelength range. Multiple blue-shift colors are achieved by SM programming process at different mechanical pressures. The blue-shift colors can be attributed to a decrease of effective BP pitch along the viewing direction caused by the compressed deformation of the BP films, which are confirmed by a three-dimensional interometric profile. The deformed BP films can recover to their original shapes and reflecting colors by heating the polymer films to temperatures above the glass-transition temperature. Quantitative relationships between the shape change and optical response are established for understanding this SM effect. What is more, the temporary photonic patterns can be reversibly written and erased for dozens of cycles without apparent degradation, making these freestanding BP films appealing as rewritable photonic papers and optical sensors.
基于液晶蓝相（BP）薄膜的光子形状记忆（SM）聚合物已通过液晶混合物的自组装和随后的光聚合来制备。这些独立的 BP 薄膜在可见光波长范围内表现出窄的光子带隙和高反射率。通过在不同机械压力下的 SM 编程过程，可以实现多种蓝移颜色。蓝移颜色可归因于 BP 薄膜压缩变形导致沿观察方向的有效 BP 节距减小，这通过三维干涉轮廓得到证实。通过将聚合物薄膜加热到玻璃化转变温度以上，可以使变形的 BP 薄膜恢复到其原始形状和反射颜色。为了理解这种 SM 效应，建立了形状变化和光学响应之间的定量关系。更重要的是，临时光子图案可以在没有明显降解的情况下可逆地写入和擦除数十次循环，这使得这些独立的 BP 薄膜成为有吸引力的可重写光子纸和光学传感器。
