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arXiv 1902.02846cond-mat.soft
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非成对排斥对纳米粒子组装的影响

Effects of non-pairwise repulsion on nanoparticle assembly

Sawyer S. Hopkins, Amitabha Chakrabarti, Jeremy D. Schmit

摘要:

静电相互作用提供了一种方便的方式来调节纳米颗粒,胶体和生物分子之间的相互作用,因为它们可以通过溶液pH值或盐浓度进行调节。虽然盐的存在提供了一种简单的方法来控制净粒子间的相互作用,由静电屏蔽引起的非线性使得难以量化的相互作用的强度。特别是,当带电粒子聚集成团簇或聚集体时,非线性效应使相互作用强烈非成对。在这里,我们报告的布朗动力学模拟研究的效果,非成对性质的静电相互作用的纳米粒子组装。我们比较这些模拟系统中的静电建模由一个严格的成对汤川势。我们发现,这两个系统显示出一个狭窄的范围内的参数空间的颗粒形成有序的晶体。与该范围相邻的是净相互作用太弱而不能稳定聚集结构的区域,或者是足够强而使系统在动力学上被困在凝胶中的区域。非成对电位不同于成对系统中的外观的非晶相强带电粒子。这个阶段的出现是因为多体静电相互作用限制了组件中可实现的最大密度。

英文摘要:

Electrostatic interactions provide a convenient way to modulate interactions between nanoparticles, colloids, and biomolecules because they can be adjusted by the solution pH or salt concentration. While the presence of salt provides an easy method to control the net interparticle interaction, the nonlinearities arising from electrostatic screening make it difficult to quantify the strength of the interaction. In particular, when charged particles assemble into clusters or aggregates, nonlinear effects render the interactions strongly non-pairwise. Here we report Brownian dynamics simulations to investigate the effect that the non-pairwise nature of electrostatic interactions has on nanoparticle assembly. We compare these simulations to a system in which the electrostatics are modeled by a strictly pairwise Yukawa potential. We find that both systems show a narrow range in parameter space where the particles form well-ordered crystals. Bordering this range are regions where the net interactions are too weak to stabilize aggregated structures, or strong enough that the system becomes kinetically trapped in a gel. The non-pairwise potential differs from the pairwise system in the appearance of an amorphous phase for strongly charged particles. This phase appears because the many-body electrostatic interactions limit the maximum density achievable in an assembly.

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