Three-Dimensional Non-Close-Packed Structures of Oppositely Charged Colloids Driven by pH Oscillation
Three-Dimensional Non-Close-Packed Structures of Oppositely Charged Colloids Driven by pH Oscillation
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pH 振荡驱动的带相反电荷胶体的三维非密堆积结构
DOI：
10.1021/acs.jpcb.8b00441
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发表时间：
2018
影响因子：
3.3
通讯作者：
Ma Yu-qiang
中科院分区：
文献类型：
--
作者：
Long Cheng;Lei Qun-li;Ren Chun-lai;Ma Yu-qiang
在胶体中实现非紧密堆积结构是具有挑战性的。利用布朗动力学模拟，我们研究了相反电荷粒子悬浮液中的非平衡自组装，其电荷量与溶液的pH值有关。在快速pH振荡条件下，得到了各种非紧密堆积(如石墨状和钻石状)结构。在这里，改变pH振荡的幅度是构建胶体动力学结构的有效方法。为了阐明动态自组装的内在机制，采用了有效势分析方法。引入了一个无量纲参数--有效斥力与有效吸力之比来反映系统中的微妙相互作用。我们发现，排斥力和吸引力之间的不平衡是结构多样性的原因。马德隆能量被用来研究这些结构的稳定性。我们的结果为在胶体中制备非紧密堆积结构提供了一种新的方法，在合成光子晶体方面具有潜在的应用前景。
The implementation of non-close-packed structures in colloids is challenging. Using Brownian dynamics simulations, we study the nonequilibrium self-assembly in suspensions of oppositely charged particles, whose charge magnitude is responsive to the pH of the solution. Under the fast pH-oscillating condition, various non-close-packed (e.g., graphitelike and diamondlike) structures are obtained. Here, changing the amplitude of the pH oscillation is an effective way to fabricate colloidal dynamic structures. To clarify the underlying mechanism of the dynamic self-assembly, the analysis of effective potential is adopted. A dimensionless parameter, the ratio of effective repulsion and attraction, is introduced to reflect the subtle interactions in the system. We find that the imbalance between repulsion and attraction is the cause of structural diversity. Madelung energy is used to study the stability of these structures. Our results provide a new way to fabricate non-close-packed structures in colloids, which has potential applications in the synthesis of photonic crystals.