Numerical Simulation of Meniscus Shape Evolution in Vertical-Deposition Convective Self-Assembly

Abstract

The convective self-assembly by vertical deposition is a promising template-free technique to arrange colloidal particles into various patterns such as stripes and grids. Through the investigation of the stripe formation process, we proposed a formation mechanism, in which the meniscus shape plays a crucial role to determine the periodicity of the structures. In the present study, we conduct lattice Boltzmann simulations of the meniscus shape evolution to further investigate the formation mechanism of stripe patterns in the vertical-deposition convective self-assembly process. We successfully simulate meniscus shapes attached to a particulate film with varied liquid level, film thickness, and interfacial tension. Our simulations demonstrate that the meniscus becomes concave toward a substrate as the liquid level drops, followed by the rupture at the thinnest point of the liquid film, and that the meniscus shape evolution is described by the Young-Laplace equation as long as the process is quasi-static. Calculated stripe spacing by analyzing the simulation results on the basis of our proposed model agrees well with experimental results, demonstrating the validity of our proposed model for the stripe formation process.