Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
Soft Matter. 2017 Sep 27;13(37):6569-6575. doi: 10.1039/c7sm00982h.
We investigated the novel photo-induced dynamics of azobenzene-doped cholesteric (Ch) droplets coexisting with the isotropic (Iso) phase. When the hemispherical Ch droplets initially stuck to glass substrates were irradiated by UV-light, they were parted from the substrates due to the surface disordering caused by the photo-isomerization of azobenzene. Then, the spherical droplets floating in the Iso phase exhibited an unexpected motion - a continuous and unidirectional rotation along the light propagation direction. The rotational direction was reversed by the inversion of either the sample's chirality or the UV irradiation direction, and the rotational velocity increased with both the UV-light intensity and the concentration of the doped azobenzene, the dependences of which were described by linear and relaxation functions, respectively. We proposed a possible scenario based on Leslie's theory combining mass fluxes and torques, which well explained the photo-driven rotation of the Ch droplets.
我们研究了偶氮苯掺杂胆甾相（Ch）液滴与各向同性（Iso）相共存时的新型光致动力学。当最初附着在玻璃基底上的半球形 Ch 液滴受到紫外光照射时，由于偶氮苯的光致异构化引起的表面无序化，它们会从基底上分离。然后，在 Iso 相中漂浮的球形液滴表现出一种意想不到的运动——沿着光的传播方向连续且单向旋转。通过反转样品的手性或紫外光照射方向，可以反转旋转方向，旋转速度随着紫外光强度和掺杂偶氮苯的浓度的增加而增加，其依赖性分别由线性和弛豫函数描述。我们基于 Leslie 理论提出了一种可能的情景，该理论结合了质量通量和扭矩，很好地解释了 Ch 液滴的光驱动旋转。
