Direct link between mechanical stability in gels and percolation of isostatic particles
Direct link between mechanical stability in gels and percolation of isostatic particles
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DOI：
10.1126/sciadv.aav6090
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发表时间：
2019-05-01
期刊：
影响因子：
13.6
通讯作者：
Tanaka, Hajime
中科院分区：
文献类型：
--
作者：
Tsurusawa, Hideyo;Leocmach, Mathieu;Tanaka, Hajime
胶体凝胶具有独特的机械和运输性质，这源于其双连续性质，其中胶体网络与粘性溶剂交织在一起，并且已经在食品、化妆品和建筑材料以及医学应用（例如软骨替代物）中发现了许多应用。到目前为止，我们对胶体凝胶化过程的理解仅限于长时间的动力学效应，其中凝胶化被视为被玻璃化转变中断的相分离过程。然而，这种纯粹的不平衡热力学图景并没有解决机械稳定性的出现。与共聚焦显微镜实验，我们发现，只有在各向同性渗流的局部均衡环境，建立凝胶的承载能力和均衡条件之间的直接联系，达到机械亚稳。我们的工作提出了一个操作性的描述凝胶的基础上的机械平衡和等静压，这些材料的稳定性和流变性提供了物理基础。
Colloidal gels have unique mechanical and transport properties that stem from their bicontinuous nature, in which a colloidal network is intertwined with a viscous solvent, and have found numerous applications in foods, cosmetics, and construction materials and for medical applications, such as cartilage replacements. So far, our understanding of the process of colloidal gelation is limited to long-time dynamical effects, where gelation is viewed as a phase separation process interrupted by the glass transition. However, this purely out-of-equilibrium thermodynamic picture does not address the emergence of mechanical stability. With confocal microscopy experiments, we reveal that mechanical metastability is reached only after isotropic percolation of locally isostatic environments, establishing a direct link between the load-bearing ability of gels and the isostaticity condition. Our work suggests an operative description of gels based on mechanical equilibrium and isostaticity, providing the physical basis for the stability and rheology of these materials.