Long Cheng, Lei Qun-Li, Ren Chun-Lai, Ma Yu-Qiang
National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China.
School of Chemical and Biomedical Engineering , Nanyang Technological University , 637459 Singapore.
J Phys Chem B. 2018 Mar 29;122(12):3196-3201. doi: 10.1021/acs.jpcb.8b00441. Epub 2018 Mar 14.
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.
在胶体中实现非密堆积结构具有挑战性。我们使用布朗动力学模拟研究了带相反电荷粒子悬浮液中的非平衡自组装，这些粒子的电荷量对溶液的pH值有响应。在快速pH振荡条件下，可获得各种非密堆积（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态结构的有效方法。为阐明动态自组装的潜在机制，我们采用了有效势分析方法。引入一个无量纲参数，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。我们发现排斥力与吸引力之间的不平衡是结构多样性的原因。利用马德隆能量研究这些结构的稳定性。我们的结果为在胶体中制造非密堆积结构提供了一种新方法，这在光子晶体的合成中具有潜在应用。
