Kim Dae-Yoon, Lee Sang-A, Park Minwook, Choi Yu-Jin, Kang Shin-Woong, Jeong Kwang-Un
Polymer Materials Fusion Research Center & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756, Korea.
Soft Matter. 2015 Apr 21;11(15):2924-33. doi: 10.1039/c5sm00073d.
A photochromic chiral molecule with azobenzene mesogens and a (R)-configuration naphthyl moiety (abbreviated as NCA2M) was specifically designed and synthesized for the demonstration of chameleon-like color changes responding to multitudinous external stimuli, such as temperature, light and electric field. The basic phase transition behaviors of NCA2M were first studied by the combination of differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Based on the structure-sensitive X-ray diffraction results obtained at different temperatures, it was comprehended that the NCA2M molecule exhibited the tilted version of highly ordered smectic crystal phase with 5.45 nm layer thickness. Chiral nematic (N*) liquid crystals (LC) with helical superstructures were formed by doping the NCA2M photochromic chiral molecule in an achiral nematic (N) LC medium. By controlling the helical pitch length of N*-LC with respect to temperature, light and electric field, the wavelength of selectively reflected light from the N* photonic crystal was finely tuned. The light-induced color change of N*-LC film was the most efficient method for covering the whole visible region from blue to green and to red, which allowed us to fabricate remote-controllable photo-responsive devices.
一种具有偶氮苯液晶元及（R）-构型萘基部分的光致变色手性分子（简称为NCA2M）被专门设计并合成出来，用于展示其对诸如温度、光和电场等多种外部刺激做出的类似变色龙的颜色变化。首先通过差示扫描量热法（DSC）和偏光显微镜（POM）相结合的方法研究了NCA2M的基本相变行为。基于在不同温度下获得的结构敏感的X射线衍射结果，可以理解NCA2M分子呈现出层厚为5.45 nm的高度有序近晶相的倾斜形式。通过将NCA2M光致变色手性分子掺杂在非手性向列相（N）液晶介质中，形成了具有螺旋超结构的手性向列相（N*）液晶。通过控制N* -液晶相对于温度、光和电场的螺旋节距长度，可以精细调节从N光子晶体选择性反射光的波长。N -液晶薄膜的光致变色是覆盖从蓝色到绿色再到红色的整个可见光区域的最有效方法，这使我们能够制造远程可控的光响应器件。
