Interparticle Interactions in Colloidal Systems: Toward a Comprehensive Mesoscale Model.
Interparticle Interactions in Colloidal Systems: Toward a Comprehensive Mesoscale Model.
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胶体系统中的粒子间相互作用：走向综合的介观尺度模型。
DOI：
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发表时间：
2017
影响因子：
9.5
通讯作者：
M. J. Abdolhosseini Qomi
中科院分区：
文献类型：
--
作者：
S. Masoumi;H. Valipour;M. J. Abdolhosseini Qomi
分子间的相互作用控制着胶体团簇的集体行为。绝大多数的文献都集中在分子间力的内聚属性，因为它们支配着干扰过程。然而，被忽视的滑动组件中起着关键作用的胶体聚集体的缓慢松弛动力学和出现不连续的剪切增稠在稠密的悬浮液。在这里，我们使用结晶硅酸钙水合物（C-S-H）作为一个模型系统，探索协同的凝聚力和滑动的相互作用。我们利用自由能微扰方法重建了水溶液中两个有限尺寸纳米层之间的平均力分布势。我们发现，滑动自由能垒衰减指数的间距增加。衰变的特征长度尺度与界面的介电常数有关。我们引入了一个简单而有效的机制来捕捉与表面粗糙度的胶体的滑动行为。此外，我们开发了一个全球的自由能景观模型并列的凝聚力和滑动的相互作用。该模型使我们能够测量的能量势垒的高度，这是必不可少的，以阐明胶体聚集体的变形机制和动力学。对于粘性胶体，我们的方法预测在滑动开始时施加的法向应力和剪切应力之间的亚线性关系，这与Amontons的摩擦定律相反。我们证明，亚线性的趋势是由于在纳米级的软接触的粘附和性质。拟议的框架提供了一个新的路线，绘制一个更现实的图片，如地质材料，水泥系统，复杂的胶体组件，和致密的悬浮液中的纳米颗粒系统的分子间相互作用。
Intermolecular interactions control the collective behavior of colloidal clusters. The overwhelming majority of literature focuses on cohesive attributes of intermolecular forces as they govern the jamming process. However, the overlooked sliding component plays a critical role in the slow relaxation dynamics of colloidal aggregates and the emergence of discontinuous shear thickening in dense suspensions. Here, we use crystalline calcium-silicate-hydrate (C-S-H) as a model system to explore synergistic cohesive and sliding interactions. We use the free energy perturbation approach to reconstruct potential of mean force profile between two finite-sized nanolayers in an aqueous environment. We show that sliding free energy barriers decay exponentially as the separation distance increases. The characteristic length scale of the decay is related to the interface corrugation. We introduce a simple yet effective mechanism to capture the sliding behavior of colloids with surface roughness. Moreover, we develop a global free energy landscape model by juxtaposing cohesive and sliding interactions. This model enables us to measure the height of energy barriers, which is essential to elucidate deformation mechanism and dynamics of colloidal aggregates. For cohesive colloids, our approach predicts a sublinear relation between applied normal and shear stress at the onset of sliding that is in contrast to Amontons' laws of friction. We demonstrate that the sublinear trend is due to the adhesion and nature of soft contact at the nanoscale. The proposed framework provides a new route to draw a more realistic picture of intermolecular interactions in nanoparticulate systems such as geomaterials, cementitious systems, complex colloidal assemblies, and dense suspensions.
影响因子：
3.4
作者：
Evans, E;Ritchie, K
通讯作者：
Ritchie, K