Mejia Andres F, Chang Ya-Wen, Ng Ratna, Shuai Min, Mannan M Sam, Cheng Zhengdong
Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jun;85(6 Pt 1):061708. doi: 10.1103/PhysRevE.85.061708. Epub 2012 Jun 20.
We demonstrate the strong dependency of the isotropic-nematic (I-N) transition of discotic suspensions on the aspect ratio (ξ = thickness/diameter) via control of the sizes of pristine ZrP crystals and subsequent exfoliation to monolayers. The size fractionation of the I-N transition facilitates the analysis of the effect of polydispersity. A systematic variation in the aspect ratio in the low aspect ratio region (0.001 < ξ < 0.01) showed that the I-N transition volume fraction increases with the aspect ratio in agreement with computer simulations. It was found that the transition volume fractions scale with aspect ratio φ_{I,N} = mξ^{1.36±0.07}, where the prefactor m strongly depends on size polydispersity for φ_{N} but does not depend on size polydispersity for φ_{I} with φ_{I} and φ_{N} being the volume fractions of the isotropic and the nematic phases on the cloud curves, respectively.
我们通过控制原始ZrP晶体的尺寸并随后将其剥离成单层，证明了盘状悬浮液的各向同性-向列相（I-N）转变对长径比（ξ = 厚度/直径）的强烈依赖性。I-N转变的尺寸分级有助于分析多分散性的影响。在低长径比区域（0.001 < ξ < 0.01）中长径比的系统变化表明，I-N转变体积分数随长径比增加，这与计算机模拟结果一致。研究发现，转变体积分数与长径比成比例关系φ_{I,N} = mξ^{1.36±0.07}，其中前因子m对于φ_{N}强烈依赖于尺寸多分散性，但对于φ_{I}不依赖于尺寸多分散性，φ_{I}和φ_{N}分别是云曲线上各向同性相和向列相的体积分数。
