SUPA and School of Physics and Astronomy, The University of Edinburgh, Edinburgh, UK.
J Phys Condens Matter. 2011 May 18;23(19):194116. doi: 10.1088/0953-8984/23/19/194116. Epub 2011 Apr 27.
We study phase separation and transient gelation experimentally in a mixture consisting of polydisperse colloids (polydispersity: ≈ 6%) and non-adsorbing polymers, where the ratio of the average size of the polymer to that of the colloid is ≈ 0.062. Unlike what has been reported previously for mixtures with somewhat lower colloid polydispersity (≈ 5%), the addition of polymers does not expand the fluid-solid coexistence region. Instead, we find a region of fluid-solid coexistence which has an approximately constant width but an unexpected re-entrant shape. We detect the presence of a metastable gas-liquid binodal, which gives rise to two-stepped crystallization kinetics that can be rationalized as the effect of fractionation. Finally, we find that the separation into multiple coexisting solid phases at high colloid volume fractions predicted by equilibrium statistical mechanics is kinetically suppressed before the system reaches dynamical arrest.
我们在由多分散胶体（分散度：≈6%）和非吸附聚合物组成的混合物中进行相分离和瞬态胶凝的实验研究，其中聚合物的平均尺寸与胶体的平均尺寸之比约为 0.062。与之前报道的胶体多分散性（≈5%）略低的混合物不同，聚合物的加入并没有扩大流体-固体共存区域。相反，我们发现了一个具有近似恒定宽度但出乎意料的再进入形状的流体-固体共存区域。我们检测到存在亚稳的气-液双节线，这导致了两步结晶动力学，这可以解释为分馏的影响。最后，我们发现，在系统达到动力学停止之前，平衡统计力学预测的高胶体体积分数下的多相共存相的分离被动力学抑制。
