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.

中文翻译：

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紫外线照射驱动胆甾型液滴单向旋转

我们研究了与各向同性（Iso）相共存的偶氮苯掺杂的胆甾型（Ch）液滴的新型光诱导动力学。当最初附着在玻璃基板上的半球形Ch液滴被紫外线照射时，由于偶氮苯的光异构化导致的表面紊乱，它们从基板上分离。然后，在Iso相中漂浮的球形液滴表现出意外的运动-沿光传播方向的连续和单向旋转。通过反转样品的手性或紫外线照射方向可以反转旋转方向，并且旋转速度随紫外线强度和掺杂的偶氮苯浓度的增加而增加，其依赖性通过线性和弛豫函数来描述， 分别。