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.

中文翻译：

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pH振荡驱动的带相反电荷的胶体的三维非密堆积结构

胶体中非紧密堆积结构的实施具有挑战性。使用布朗动力学模拟，我们研究了带相反电荷的粒子悬浮液中的非平衡自组装，其电荷量对溶液的pH值有响应。在快速的pH振荡条件下，获得了各种非密堆积的（例如，类石墨和类金刚石）结构。在此，改变pH振荡的幅度是制造胶体动力学结构的有效方法。为了阐明动态自组装的潜在机制，采用了有效势的分析。引入了无量纲参数，即有效排斥力与吸引力之比，以反映系统中的微妙相互作用。我们发现排斥和吸引之间的不平衡是结构多样性的原因。马德隆能量用于研究这些结构的稳定性。我们的结果提供了一种在胶体中制备非紧密堆积结构的新方法，该方法在光子晶体的合成中具有潜在的应用。