Buckling of a monolayer of plate-like particles trapped at a fluid-fluid interface

Abstract

Particles trapped at a fluid-fluid interface by capillary forces can form a monolayer that jams and buckles when subject to uni-axial compression. Here we investigate experimentally the buckling mechanics of monolayers of millimeter-sized rigid plates trapped at a planar fluid-fluid interface subject to uni-axial compression in a Langmuir trough. We quantified the buckling wavelength and the associated force on the trough barriers as a function of the degree of compression. To explain the observed buckling wavelength and forces in the two-dimensional monolayer, we consider a simplified system composed of a linear chain of plate-like particles. The chain system enables us to build a theoretical model which is then compared to the two-dimensional monolayer data. Both the experiments and analytical model show that the wavelength of buckling of a monolayer of plate-like particles is of the order of the particle size, a different scaling from the one reported for monolayers of spheres. A simple model of buckling surface pressure is also proposed, and an analysis of the effect of the bending rigidity resulting from a small overlap between nanosheet particles is presented. These results can be applied to the modeling of the interfacial rheology and buckling dynamics of interfacial layers of 2D nanomaterials.