Nonlinear Continuum Theory¶of Smectic-A Liquid Crystals
Nonlinear Continuum Theory¶of Smectic-A Liquid Crystals
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DOI：
10.1007/s002050050026
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发表时间：
1997-06
影响因子：
2.5
通讯作者：
Weinan E Courant
中科院分区：
文献类型：
--
作者：
Weinan E Courant
近晶A是一种液晶相，其中不仅存在一定程度的取向有序性，还存在一定程度的位置有序性。在近晶A相中，分子自组织成层。在每一层内，分子像在普通液体中一样自由扩散。我们可以认为近晶A液晶是垂直于层的一维晶体，层内是二维液体。在这个意义上，近晶A液晶提供了结晶液体的最简单的例子。请注意，向列相并不符合结晶的条件，因为它们没有任何位置顺序。近晶A的动力学之所以独特是因为渗透的可能性--分子的速度和同一空间位置上的层的速度可能不同。因此，分子可能会渗透到这些层中[7]。这种渗透过程的独特之处在于，渗透剂和底层的多孔介质是由同一种物质组成的--组成分子。事实上，这种独特的渗透过程是近晶A液晶动力学和相变中观察到的许多不寻常行为的原因[4]。
Smectic A is a liquid crystalline phase in which not only some degree of orientational order is present, there is also some degree of positional order. In the smectic A phase, molecules organize themselves into layers. Within each layer the molecules diffuse freely just as in ordinary liquids. We can think of smectic A liquid crystals as being a one-dimensional crystal in the direction normal to the layers, and a two dimensional liquid within the layers. In this sense smectic A liquid crystals provide the simplest example of crystalline liquids. Notice that nematics do not qualify as being crystalline since they do not have any positional order.What makes the dynamics of smectic A unique is the possibility of permeation–the velocity of the molecules and the velocity of the layers at the same spatial location may not be the same. As a result, molecules may permeate through the layers [7]. What makes this permeation process unique is that the permeating agent and the underlying porous medium are made of the same thing–the constituent molecules. Indeed this unique permeation process is responsible for many of the unusual behavior observed in the dynamics and phase transition of smectic A liquid crystals [4].