Recognition of Spatial Finiteness in Meniscus Splitting Based on Evaporative Interface Fluctuations

Abstract The geometric deformation of viscous fingering is useful for understanding natural multiscale patterns and designing dissipative structures in materials. Although the spatio‐temporal patterns in soft materials are reported previously, there is a lack of research on the spatial finiteness and boundary effects. In this study, the recognition of spatial finiteness in “meniscus splitting phenomena” in aqueous polymer dispersions during water evaporation is demonstrated. By providing heat energy to polymer dispersions in a Hele‐Shaw cell, an interface fluctuation with concentration unevenness is induced to split the evaporative interface. The spatial finiteness of the interface causes asynchronous nucleation, which is demonstrated using polysaccharide dispersions. The results of the quasi‐natural experiments revealed that the nonequilibrium drying/wetting period for repositioning polymer clusters allows for considerable changes in Reynolds number in a low range (<10⁻⁶) to form multiple nuclei. This splitting method will be universally useful in various fields, including fluid dynamics, biology, and microfluidics, as well as non‐equilibrium, colloid, interface, polymer, and materials sciences.