(216s) Lattice Boltzmann Simulation of the Meniscus Shape Evolution in Vertical-Deposition Convective Self-Assembly

Patterned structures of colloidal particles exhibit physically and chemically peculiar characteristics for various applications, including plasmonic materials, photonic materials, and sensors. Establishment of patterning techniques is thus of increasing importance for engineering materials functions. Among the fabrication techniques, bottom-up self-assembly methods are promising because of their inexpensive and energy saving approach. In the present study, we focus on the vertical-deposition convective self-assembly technique. In this technique, particles are carried into the contact line by a solvent convective flow induced by the evaporation, and arranged into an ordered array by attractive capillary forces acting between particles. So far, we have succeeded in producing colloidal patterns, such as stripes, grids and cluster arrays, and investigated the formation mechanism of the patterned structures by directly observing the processes. Through the investigation, we have found out that the deformation of the meniscus shape plays a crucial role in the pattern formation process. However, detailed mechanism has not yet been clarified, which is firstly because the self-organization process intrinsically contains intricate nano- and microscale phenomena, such as evaporation, convective flow, heat transfer, meniscus shape evolution, and particles motion, and secondary because experimental approaches are limited in giving one a deep understanding of the complex phenomenon due to finite time and space resolutions. In this regard, numerical simulation is a possible alternative and quite suitable for revealing the key physics behind the assembly process. In the present study, we conduct a lattice Boltzmann simulation of the meniscus shape evolution in order to capture the complex phenomena involved in the vertical-deposition convective self-assembly process. We clarify the relationship between self-assembled structure and dynamics of the meniscus and particles under different conditions.