Vogel M, Lekkerkerker HN
Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Oct;62(4 Pt B):5397-402. doi: 10.1103/physreve.62.5397.
Suspensions of sterically stabilized colloidal gibbsite platelets have recently been found to exhibit both an isotropic-nematic (I-N) and a nematic-columnar (N-C) phase transition. In the present paper we show that depletion attraction, brought about by the addition of nonadsorbing polymer, enriches the phase behavior of these platelet suspensions even further. Pronounced broadening of the isotropic-nematic gap occurs, with purely nematic samples re-entering the biphasic state by the addition of nonadsorbing polymer. At the same time, depletion attraction enhances size fractionation between coexisting phases, which actually provides an effective means for reducing the polydispersity of the suspensions. An additional isotropic phase emerges, which leads to the appearance of several three-phase equilibria and even a four-phase equilibrium. We explain the observed topology of the phase diagram by the interplay between depletion attraction and the platelets' polydispersity.
最近发现，空间稳定的胶体三水铝石片状颗粒悬浮液表现出各向同性向列相（I-N）和向列柱状相（N-C）两种相变。在本文中，我们表明，通过添加非吸附性聚合物产生的耗尽吸引作用，进一步丰富了这些片状颗粒悬浮液的相行为。各向同性向列相间隙明显变宽，通过添加非吸附性聚合物，纯向列相样品重新进入双相状态。同时，耗尽吸引增强了共存相之间的尺寸分级，这实际上提供了一种有效降低悬浮液多分散性的方法。出现了一个额外的各向同性相，导致出现几个三相平衡甚至一个四相平衡。我们通过耗尽吸引与片状颗粒多分散性之间的相互作用来解释所观察到的相图拓扑结构。
