Quantized Self-Assembly of Discotic Rings in a Liquid Crystal Confined in Nanopores.
Quantized Self-Assembly of Discotic Rings in a Liquid Crystal Confined in Nanopores.
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DOI：
10.1103/physrevlett.120.067801
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发表时间：
2018-01
影响因子：
8.6
通讯作者：
K. Sentker;A. Zantop;M. Lippmann;T. Hofmann;O. Seeck;A. Kityk;A. Yıldırım;A. Schönhals;M. Mazza;P. Huber
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作者：
K. Sentker;A. Zantop;M. Lippmann;T. Hofmann;O. Seeck;A. Kityk;A. Yıldırım;A. Schönhals;M. Mazza;P. Huber
具有芳香核的类芳香分子自发地堆积在具有高的线性柱中，一维电荷载流子迁移率沿柱轴沿着，使它们成为功能性自组织物质的突出模型系统。我们通过高分辨率的光学双折射和基于同步加速器的X射线衍射表明，将热致dispersion液晶限制在圆柱形纳米孔中会导致由同心圆弯曲柱组成的环形层的量子化形成，这在体状态下是未知的。从壁开始，该环自组装逐层传播到块体各向同性柱状过渡的过冷域中的孔中心，从而允许通过小的温度变化可逆地打开和关闭单个纳米级环。通过建立一个吉布斯自由能相图，我们跟踪的相变量子化的层的多余的弯曲变形能的离散性相比的热能，即使对于这个近室温系统。蒙特卡罗模拟产生空间分辨的有序参数，密度图，和键取向的顺序参数证实了约束诱导的柱状环形成的普遍性和鲁棒性，以及它的量化性质。
Disklike molecules with aromatic cores spontaneously stack up in linear columns with high, one-dimensional charge carrier mobilities along the columnar axes, making them prominent model systems for functional, self-organized matter. We show by high-resolution optical birefringence and synchrotron-based x-ray diffraction that confining a thermotropic discotic liquid crystal in cylindrical nanopores induces a quantized formation of annular layers consisting of concentric circular bent columns, unknown in the bulk state. Starting from the walls this ring self-assembly propagates layer by layer towards the pore center in the supercooled domain of the bulk isotropic-columnar transition and thus allows one to switch on and off reversibly single, nanosized rings through small temperature variations. By establishing a Gibbs free energy phase diagram we trace the phase transition quantization to the discreteness of the layers' excess bend deformation energies in comparison to the thermal energy, even for this near room-temperature system. Monte Carlo simulations yielding spatially resolved nematic order parameters, density maps, and bond-orientational order parameters corroborate the universality and robustness of the confinement-induced columnar ring formation as well as its quantized nature.