Direct imaging of contacts and forces in colloidal gels.
Direct imaging of contacts and forces in colloidal gels.
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DOI：
10.1063/5.0089276
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Jun Dong;F. Turci;R. Jack;M. Faers;C. Royall
中科院分区：
文献类型：
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作者：
Jun Dong;F. Turci;R. Jack;M. Faers;C. Royall
胶体分散体被认为是了解材料基本性质的模型系统，是从化妆品到食品再到农用化学品的广泛行业的核心。在使用胶体来解决凝聚态中的挑战方面，关键的发展之一是在3D中解析粒子坐标，从而实现通常只有在计算机模拟中才能实现的分析水平。然而，在非晶态材料中，将机械性能与微观结构联系起来仍然是个问题。这使得它相当难以理解，例如，机械故障。在这里，我们通过研究粒子之间的接触和作用力以及它们的位置来应对这一挑战。为此，我们使用了胶体模型系统(乳化液)，在该系统中，颗粒间力和局部应力可以与微观结构联系起来。我们展示了我们的方法的潜力，揭示了通过测定胶体凝胶中的局部应力来洞察软无定形固体的破坏机制。特别是，我们确定了承载液滴的“力链”和局部应力各向异性，并研究了它们与液滴局部刚性填充的联系。
Colloidal dispersions are prized as model systems to understand the basic properties of materials and are central to a wide range of industries from cosmetics to foods to agrichemicals. Among the key developments in using colloids to address challenges in condensed matter is to resolve the particle coordinates in 3D, allowing a level of analysis usually only possible in computer simulations. However, in amorphous materials, relating mechanical properties to microscopic structure remains problematic. This makes it rather hard to understand, for example, mechanical failure. Here, we address this challenge by studying the contacts and the forces between particles as well as their positions. To do so, we use a colloidal model system (an emulsion) in which the interparticle forces and local stress can be linked to the microscopic structure. We demonstrate the potential of our method to reveal insights into the failure mechanisms of soft amorphous solids by determining local stress in a colloidal gel. In particular, we identify "force chains" of load-bearing droplets and local stress anisotropy and investigate their connection with locally rigid packings of the droplets.