Mondiot Frédéric, Loudet Jean-Christophe, Mondain-Monval Olivier, Snabre Patrick, Vilquin Alexandre, Würger Alois
Centre de Recherche Paul Pascal, Université de Bordeaux and CNRS, 33600 Pessac, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jul;86(1 Pt 1):010401. doi: 10.1103/PhysRevE.86.010401. Epub 2012 Jul 5.
We report the experimental observation of anisotropic diffusion of polystyrene particles immersed in a lyotropic liquid crystal with two different anchoring conditions. Diffusion is shown to obey the Stokes-Einstein law for particle diameters ranging from 190 nm up to 2 μm. In the case of prolate micelles, the beads diffuse four times faster along the director than in perpendicular directions, D||/D[Symbol: see text] ≈ 4. In the theory part we present a perturbative approach to the Leslie-Ericksen equations and relate the diffusion coefficients to the Miesovicz viscosity parameters η(i). We provide explicit formulas for the cases of uniform director field and planar anchoring conditions which are then discussed in view of the data. As a general rule, we find that the inequalities η(b) <η(a) <η(c), satisfied by various liquid crystals of rodlike molecules, imply D||>D[Symbol: see text].
我们报告了在两种不同锚定条件下，浸没在溶致液晶中的聚苯乙烯颗粒各向异性扩散的实验观察结果。对于直径范围从190纳米到2微米的颗粒，扩散遵循斯托克斯 - 爱因斯坦定律。在长棒状胶束的情况下，珠子沿指向矢方向的扩散速度比垂直方向快四倍，D||/D[符号：见正文]≈4。在理论部分，我们提出了一种对莱斯利 - 埃里克森方程的微扰方法，并将扩散系数与米索维奇粘度参数η(i)联系起来。我们给出了均匀指向矢场和平面锚定条件情况下的明确公式，然后根据数据进行讨论。一般来说，我们发现由各种棒状分子液晶满足的不等式η(b)<η(a)<η(c)意味着D||>D[符号：见正文]。
