Department of Chemistry, University of California, Berkeley, California 94720, USA.
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA.
Phys Rev Lett. 2019 Sep 6;123(10):100602. doi: 10.1103/PhysRevLett.123.100602.
We present a model for glassy dynamics in supercooled liquid mixtures. Given the relaxation behavior of individual supercooled liquids, the model predicts the relaxation times of their mixtures as temperature is decreased. The model is based on dynamical facilitation theory for glassy dynamics, which provides a physical basis for relaxation and vitrification of a supercooled liquid. This is in contrast to empirical linear interpolations such as the Gordon-Taylor equation typically used to predict glass transition temperatures of liquid mixtures. To understand the behavior of supercooled liquid mixtures we consider a multicomponent variant of the kinetically constrained East model in which components have a different energy scale and can also diffuse when locally mobile regions, i.e., excitations, are present. Using a variational approach we determine an effective single component model with a single effective energy scale that best approximates a mixture. When scaled by this single effective energy, we show that experimental relaxation times of many liquid mixtures all collapse onto the "parabolic law" predicted by dynamical facilitation theory. The model can be used to predict transport properties and glass transition temperatures of mixtures of glassy materials, with implications in atmospheric chemistry, biology, and pharmaceuticals.
我们提出了一个过冷液体混合物的玻璃态动力学模型。给定各过冷液体的弛豫行为，该模型可以预测混合物在温度降低时的弛豫时间。该模型基于玻璃态动力学的动力学促进理论，为过冷液体的弛豫和玻璃化提供了物理基础。这与通常用于预测液体混合物玻璃化转变温度的经验线性插值（如 Gordon-Taylor 方程）形成对比。为了理解过冷液体混合物的行为，我们考虑了动力学受限的 East 模型的多组分变体，其中各组分具有不同的能量标度，并且在局部移动区域（即激发态）存在时也可以扩散。我们使用变分方法确定了一个最佳逼近混合物的有效单组分模型，该模型具有单个有效能量标度。当按此单个有效能量进行缩放时，我们表明许多液体混合物的实验弛豫时间都符合动力学促进理论预测的“抛物线律”。该模型可用于预测玻璃态材料混合物的输运性质和玻璃化转变温度，在大气化学、生物学和药物学等领域具有重要意义。
