Electric-Field-Driven Assembly of Dipolar Spheres Asymmetrically Confined between Two Electrodes
Electric-Field-Driven Assembly of Dipolar Spheres Asymmetrically Confined between Two Electrodes
复制标题
电场驱动的不对称限制在两个电极之间的偶极球体组装
DOI：
10.1021/acsnano.0c04939
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发表时间：
2021
期刊：
影响因子：
17.1
通讯作者：
Wu, David T.
中科院分区：
文献类型：
--
作者：
Maestas, Joseph R.;Ma, Fuduo;Wu, Ning;Wu, David T.
外部施加的电场先前已被用于引导限制在表面处的胶体颗粒组装成各种各样的胶体低聚物和非密堆积的蜂窝晶格（J. Am. 2013，135，7839-7842）。观察到在这种限制和场作用下的胶体在电极附近自发地组织成双层。为了扩展和更好地理解粒子如何聚集在一起形成准二维材料，我们对在施加的交流电场下强烈限制在两个电极之间的胶体进行了Monte Carlo模拟和补充实验，控制场强和粒子面积分数。特别重要的是，我们控制的uppervslower平面，我们描述为不对称的限制，并有效地调制在每个平面中的粒子的配位数的粒子的分数。我们使用Stockmayer势来模拟粒子-粒子相互作用，以捕获由电场引起的偶极相互作用。相图，然后描绘为控制参数的函数，并开发了一个理论模型，其中几个理想化的晶格的能量进行计算和比较。我们发现，所得的理论相图与模拟吻合得很好。我们不仅使用接近实验条件的参数再现了实验中观察到的结构，而且还在模拟中发现了几个以前未观察到的相，包括矩形带，zig zags和sigma晶格的网络，然后我们能够在实验中确认。我们进一步提出了一种简单的方法来精确控制不同平面之间的粒子的数量比，即叠加一个直流电场与交流电场，这可以在实验中方便地实现。我们的工作表明，可以从相对简单的成分中组装出各种材料，通过模拟、理论和实验的比较，可以有效地分析这些材料。我们的模型进一步解释了不同阶段之间的可能途径，并为检查尚未在实验中观察到的阶段提供了一个平台。
Externally applied electric fields have previously been utilized to direct the assembly of colloidal particles confined at a surface into a large variety of colloidal oligomers and nonclose-packed honeycomb lattices (J. Am. Chem. Soc.2013,135, 7839–7842). The colloids under such confinement and fields are observed to spontaneously organize into bilayers near the electrode. To extend and better understand how particles can come together to form quasi-two-dimensional materials, we have performed Monte Carlo simulations and complementary experiments of colloids that are strongly confined between two electrodes under an applied alternating current electric field, controlling field strength and particle area fraction. Of particular importance, we control the fraction of particles in the uppervslower plane, which we describe as asymmetric confinement, and which effectively modulates the coordination number of particles in each plane. We model the particle–particle interactions using a Stockmayer potential to capture the dipolar interactions induced by the electric field. Phase diagrams are then delineated as a function of the control parameters, and a theoretical model is developed in which the energies of several idealized lattices are calculated and compared. We find that the resulting theoretical phase diagrams agree well with simulation. We have not only reproduced the structures observed in experiments using parameters that are close to experimental conditions but also found several previously unobserved phases in the simulations, including a network of rectangular bands, zig zags, and a sigma lattice, which we were then able to confirm in experiment. We further propose a simple way to precisely control the number ratio of particles between different planes, that is, superimposing a direct current electric field with the alternating current electric field, which can be implemented conveniently in experiments. Our work demonstrates that a diverse collection of materials can be assembled from relatively simple ingredients, which can be analyzed effectively through comparison of simulation, theory, and experiment. Our model further explains possible pathways between different phases and provides a platform for examining phases that have yet to be observed in experiments.