  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.
