Mild stratification in drying films of colloidal mixtures

• Published in: Soft matter Vol. 18; no. 18; pp. 3487 - 3497
• Main Authors: Park, Jin Seok, Yun, Jinseong, Chun, Byoungjin, Jung, Hyun Wook
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 11.05.2022
• Subjects: Concentration gradient; Drying; Mixtures; Simulation; Solvents; Stratification
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/d2sm00205a

Size stratification of bidisperse colloidal mixtures during vertical drying was investigated using the implicit solvent Langevin dynamics (LD) simulation and the explicit solvent lattice Boltzmann (LB) method. Simulations were performed for the Péclet number ( Pe ) over a wide range of 1-1000. In the case of a low size ratio of 2, mild stratification was observed in both simulation methods, in contrast to distinct stratification with thick "small-on-top" or "large-on-top" layers. The LD simulations exhibited a "small-on-top" stratification or mixed state. In contrast, the LB simulations exhibited a "large-on-top" or mixed state, according to the variation in Pe . The results demonstrated that the explicit solvent reduced the collective diffusion under moderate Pe conditions. This suppressed the steep concentration gradient of small particles in the packed region of particles near the air-solvent interface. Thus, distinguishable stratification patterns were obtained for the implicit and explicit solvent models. Analysis on the size stratifications in bidisperse colloidal film drying using the implicit and explicit solvent simulations.