从悬浮液到多孔多层膜：胶体薄膜干燥过程中的微结构形成与颗粒堆积
From suspensions to porous multilayers: microstructure formation and particle packing in drying colloidal films
AI总结：
本研究通过数值模拟结合理论模型，揭示胶体薄膜干燥时颗粒间相互作用决定最终多孔结构，为定制功能层提供指导。
AI中文摘要：
干燥颗粒悬浮液被广泛用于组装颗粒并制备适用于各类应用的多孔功能层，其中微结构特性对器件整体性能至关重要。因此，理解干燥诱导微结构形成的机制，对实现所得结构的可预测控制具有重要意义。本研究通过数值方法探究颗粒悬浮液薄膜干燥过程中的微结构演化，重点关注颗粒间相互作用的作用。对于弱相互作用颗粒，颗粒在界面处组装成六边形结构，干燥时触发后续逐层组装；我们提出一个简单理论模型预测层厚的时间演化，并用模拟结果验证该模型。对于强颗粒相互作用，颗粒在干燥过程中聚集形成网状结构，最终得到多孔沉积物；该结构的孔隙率遵循与无量纲粘附参数的幂律关系，该参数表征颗粒间相互作用力与毛细管力的相对大小。通过系统改变粘附参数，确定了最终结构的三种堆积 regime：密排六方堆积、随机密堆积和粘附堆积。总体而言，本研究结果表明颗粒间相互作用对最终多孔结构起决定性作用，为通过可控调节颗粒相互作用来定制功能层提供了实用指导。
英文摘要：
Drying particle suspensions is widely used to assemble particles and to fabricate porous functional layers for various applications, in which microstructural properties critically influence the overall device performance. Understanding the mechanisms governing drying-induced microstructure formation is therefore essential for predictive control of the resulting structures. In this work, we numerically investigate the evolution of microstructures during the drying of particle suspension films, with a particular focus on the role of particle-particle interactions. For weakly interacting particles, the particles assemble into hexagonal structures at the interface, and upon drying, trigger subsequent layer-by-layer assembly. We present a simple theoretical model to predict the time evolution of the layer thickness, validated against our simulation results. With strong particle interactions, the particles aggregate and form a network-like structure during drying, leading to a porous deposit. The porosity of the structure follows a power-law relationship with a dimensionless adhesion parameter that characterizes the particle-particle interaction force relative to the capillary force. By systematically varying the adhesion parameter, three packing regimes of the final structure are identified: hexagonal close packing, random close packing, and adhesive packing. Overall, our results demonstrate that particle-particle interactions play a decisive role in determining the final porous structure, providing practical guidance for tailoring functional layers through controlled manipulation of particle interactions.
