近日，法国蒙彼利埃大学的Luca Cipelletti及其研究小组取得一项新进展。经过不懈努力，他们成功获得了软胶体屈服转变的统一状态图。相关研究成果已于2023年7月27日在国际知名学术期刊《自然—物理学》上发表。

该研究团队对三类互斥软固体的屈服现象进行了研究，发现微观层面上屈服现象是由两种不同动力学状态之间的转变组成的。为了解释这一点，研究人员提出一个晶格模型，该模型具有相邻位置之间的动态耦合，从而得到了一个统一的屈服状态图。采用与真实气体的范德华相图的类比，研究表明，在屈服过程中，与临界点的距离对于类一阶与类二阶特征的出现起着重要作用，从而调和了先前对转变性质的对比观察。

据悉，浓缩的胶体悬浮液和乳液是非晶态软固体，在技术和工业中得到广泛应用，并作为物理和材料科学的模型系统进行研究。通过施加机械应力，这些物质可以轻易地流动，并经历尚未得到统一描述的屈服转变。

附：英文原文

Title: A unified state diagram for the yielding transition of soft colloids

Author: Aime, Stefano, Truzzolillo, Domenico, Pine, David J., Ramos, Laurence, Cipelletti, Luca

Issue&Volume: 2023-07-27

Abstract: Concentrated colloidal suspensions and emulsions are amorphous soft solids, widespread in technological and industrial applications and studied as model systems in physics and materials sciences. They are easily fluidized by applying mechanical stress, undergoing a yielding transition that still lacks a unified description. Here we investigate yielding in three classes of repulsive soft solids and find that at the microscopic level, yielding consists of a transition between two distinct dynamical states. We rationalize this by proposing a lattice model with dynamical coupling between neighbouring sites, leading to a unified state diagram for yielding. Employing the analogy with van der Waals phase diagram for real gases, we show that distance from a critical point plays a major role in the emergence of first-order-like versus second-order-like features in yielding, thereby reconciling previously contrasting observations on the nature of the transition.

DOI: 10.1038/s41567-023-02153-w

Source: https://www.nature.com/articles/s41567-023-02153-w