Structural correlations in highly asymmetric binary charged colloidal mixtures,Physical Chemistry Chemical Physics

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Structural correlations in highly asymmetric binary charged colloidal mixtures
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2022-06-13 , DOI: 10.1039/d2cp01343f
Elshad Allahyarov _{1,

2,

3} , Hartmut Löwen ₂ , Alan R Denton ₄

Affiliation

We explore structural correlations of strongly asymmetric mixtures of binary charged colloids within the primitive model of electrolytes considering large charge and size ratios of 10 and higher. Using computer simulations with explicit microions, we obtain the partial pair correlation functions between the like-charged colloidal macroions. Interestingly the big–small correlation peak amplitude is smaller than that of the big–big and small–small macroion correlation peaks, which is unfamiliar for additive repulsive interactions. Extracting optimal effective microion-averaged pair interactions between the macroions, we find that on top of non-additive Yukawa-like repulsions an additional shifted Gaussian attractive potential between the small macroions is needed to accurately reproduce their correct pair correlations. For small Coulomb couplings, the behavior is reproduced in a coarse-grained theory with microion-averaged effective interactions between the macroions. However, the accuracy of the theory deteriorates with increasing Coulomb coupling. We emphasize the relevance of entropic interactions exerted by the microions on the macroions. Our results are experimentally verifiable in binary mixtures of micron-sized colloids and like-charge nanoparticles.

中文翻译：

高度不对称二元带电胶体混合物中的结构相关性

考虑到 10 或更高的大电荷和尺寸比，我们探索了电解质原始模型中二元带电胶体的强不对称混合物的结构相关性。使用具有显式微离子的计算机模拟，我们获得了类似电荷的胶体宏观之间的部分对相关函数。有趣的是，大-小相关峰幅度小于大-大和小-小宏观相关峰的幅度，这对于加性排斥相互作用是不熟悉的。提取宏观之间的最佳有效微离子平均对相互作用，我们发现除了非加性 Yukawa 样排斥之外，还需要小宏观之间额外的移位高斯吸引力势来准确再现它们正确的对相关性。对于小型库仑联轴器，该行为在粗粒度理论中重现，宏观之间具有微离子平均的有效相互作用。然而，该理论的准确性随着库仑耦合的增加而下降。我们强调由微离子对宏观施加的熵相互作用的相关性。我们的结果可以在微米级胶体和类似电荷纳米粒子的二元混合物中进行实验验证。

更新日期：2022-06-16

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