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Linking slow dynamics and microscopic connectivity in dense suspensions of charged colloids†
Soft Matter ( IF 2.9 ) Pub Date : 2017-12-21 00:00:00 , DOI: 10.1039/c7sm01781b
Ruben Higler 1, 2, 3, 4 , Johannes Krausser 5, 6, 7, 8 , Jasper van der Gucht 1, 2, 3, 4 , Alessio Zaccone 5, 6, 7, 8 , Joris Sprakel 1, 2, 3, 4
Affiliation  

The quest to unravel the nature of the glass transition, where the viscosity of a liquid increases by many orders of magnitude, while its static structure remains largely unaffected, remains unresolved. While various structural and dynamical precursors to vitrification have been identified, a predictive and quantitative description of how subtle changes at the microscopic scale give rise to the steep growth in macroscopic viscosity is missing. It was recently proposed that the presence of long-lived bonded structures within the liquid may provide the long-sought connection between local structure and global dynamics. Here we directly observe and quantify the connectivity dynamics in liquids of charged colloids en route to vitrification using three-dimensional confocal microscopy. We determine the dynamic structure from the real-space van Hove correlation function and from the particle trajectories, providing upper and lower bounds on connectivity dynamics. Based on these data, we extend Dyre's model for the glass transition to account for particle-level structural dynamics; this results in a microscopic expression for the slowing down of relaxations in the liquid that is in quantitative agreement with our experiments. These results indicate how vitrification may be understood as a dynamical connectivity transition with features that are strongly reminiscent of rigidity percolation scenarios.

中文翻译:

在带电胶体的密集悬浮液中将慢速动力学和微观连通性联系起来

揭开玻璃化转变的本质的探索仍未解决,在该转变中,液体的粘度增加了多个数量级,而其静态结构仍未受影响。尽管已经确定了玻璃化的各种结构和动力学前体,但仍缺乏对微观尺度上的细微变化如何引起宏观粘度急剧增长的预测和定量描述。最近有人提出,在液体中存在长寿命的键合结构可能会在局部结构和整体动力学之间提供长期的联系。在这里,我们直接观察和量化带电胶体在途中液体的连通性动力学使用三维共聚焦显微镜进行玻璃化。我们从实空间范霍夫相关函数和粒子轨迹确定动态结构,从而提供连通性动力学的上限和下限。基于这些数据,我们扩展了玻璃转变的Dyre模型,以解决颗粒级结构动力学问题。这导致了液体中弛豫减慢的微观表达,这与我们的实验在数量上是一致的。这些结果表明,玻璃化可以理解为动态连接性过渡,其特征强烈地让人联想到刚性渗透的情况。
更新日期:2017-12-21
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