Mechanistic Principles of Colloidal Crystal Growth by Evaporation-Induced Convective Steering
Mechanistic Principles of Colloidal Crystal Growth by Evaporation-Induced Convective Steering
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DOI：
10.1021/la802180d
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发表时间：
2008-12-02
期刊：
影响因子：
3.9
通讯作者：
Scriven, L. E.
中科院分区：
文献类型：
--
作者：
Brewer, Damien D.;Allen, Joshua;Scriven, L. E.
我们使用等效网络模型模拟了蒸发驱动的胶体晶体自组装。描述了规则的六边形紧密堆积的坚硬、单分散球体阵列、相关的孔隙空间和面心立方微结构扩展的选择性机制之间的关系。通过考虑接触线重排和在一系列暴露的半月板上的蒸发，等效网络模型描述了溶剂在刚性胶体晶体中的蠕动流动。根据对流导向假说解释了有关胶体晶体生长的观察结果，该假说假设溶剂流入和流过晶体的孔隙空间可能在胶体自组装中起主要作用。高Peclet数刚性球形粒子在晶体边界的对流导向和沉积是从空间分辨的溶剂流入晶体中推断出来的。由于边界通道相对于固定的自由面接触线的空间分布，预测了通过边界通道的局部流动的梯度。基于均匀的溶剂和粒子通量作为特定生长面稳定性的判据，这些网络模拟表明，倾斜的{311}晶界是稳定的，这是一个只传播FeE微结构的对称面。交替晶面的网络模拟表明，择优生长前沿向倾斜的{311}界面演化，这与所提出的对流组装中择优取向微结构扩展的稳定机制一致。
We simulate evaporation-driven self-assembly of colloidal crystals using an equivalent network model. Relationships between a regular hexagonally close-packed array of hard, monodisperse spheres, the associated pore space, and selectivity mechanisms for face-centered cubic microstructure propagation are described. By accounting for contact line rearrangement and evaporation at a series of exposed menisci, the equivalent network model describes creeping flow of solvent into and through a rigid colloidal crystal. Observations concerning colloidal crystal growth are interpreted in terms of the convective steering hypothesis, which posits that solvent flow into and through the pore space of the crystal may play a major role in colloidal self-assembly. Aspects of the convective steering and deposition of high-Peclet-number rigid spherical particles at a crystal boundary are inferred from spatially resolved solvent flow into the crystal. Gradients in local flow through boundary channels were predicted due to the channels' spatial distribution relative to a pinned free surface contact line. On the basis of a uniform solvent and particle flux as the criterion for stability of a particular growth plane, these network simulations suggest the stability of a declining {311} crystal interface, a symmetry plane which exclusively propagates fee microstructure. Network simulations of alternate crystal planes suggest preferential growth front evolution to the declining {311} interface, in consistent agreement with the proposed stability mechanism for preferential fee microstructure propagation in convective assembly.