Gregorc Marko, Li Hui, Domenici Valentina, Ambrožič Gabriela, Čopič Martin, Drevenšek-Olenik Irena
J. Stefan Institute, Jamova 39, Ljubljana, SI 1000, Slovenia.
Nankai University, TEDA APS, 23 Hongda Street, Tianjin 300457, China.
Materials (Basel). 2012 Apr 25;5(5):741-753. doi: 10.3390/ma5050741.
The optical mechanism for imprinting one-dimensional grating structures into thin films of a light-sensitive monodomain liquid crystal elastomer is investigated by analyzing the time dependence of optical diffraction properties. The recording kinetics shows an irregular oscillatory behavior, which is most expressed at small grating spacings and at temperatures close to the nematic-isotropic phase transition. The oscillations are attributed to the opto-mechanical response of the film, i.e., to contraction of the film during the recording process. At temperatures far below the nematic-isotropic phase transition, the spontaneous erasure kinetics exhibits exponential relaxation with relaxation time following the Arrhenius activation law. However, at temperatures close to the nematic-isotropic phase transition, the erasure process shows an interesting nonmonotonic behavior that we attribute to the non-linear relation between the concentration of the photo-transformed chemical groups and the nematic order parameter.
通过分析光学衍射特性的时间依赖性，研究了将一维光栅结构印刻到光敏单畴液晶弹性体薄膜中的光学机制。记录动力学呈现出不规则的振荡行为，这种行为在小光栅间距以及接近向列相 - 各向同性相转变的温度下最为明显。这些振荡归因于薄膜的光机械响应，即在记录过程中薄膜的收缩。在远低于向列相 - 各向同性相转变的温度下，自发擦除动力学呈现指数弛豫，弛豫时间遵循阿仑尼乌斯活化定律。然而，在接近向列相 - 各向同性相转变的温度下，擦除过程表现出一种有趣的非单调行为，我们将其归因于光转化化学基团浓度与向列序参量之间的非线性关系。
