Elastic sheets in shear flows, from single sheet behavior to exfoliation process: an experimental study.*

Graphene has attracted much attention as a candidate material for applications in a variety fields. However, the fabrication of graphene at industrial scale remains a challenge. One of the most promising techniques is so-called liquid-phase exfoliation: graphite is sheared in a liquid until layers of graphene detach.
While being poorly understood, the mechanism of exfoliation is known to rely on three physical ingredients: adhesion, bending rigidity and the imposed viscous flow. For the dynamic processes, exfoliation can be composed of different modes of deformation: peeling of two sheets, sliding between two sheets or a buckling instability. To investigate the role of the three ingredients and the modes of deformation, here we present the first model experiment of elastic adhesive sheets in shear flows at the macroscopic scale. As a requirement one needs to understand the characteristics of viscous forces exerted on a single elastic sheet, to answer that question, we performed systematic studies of the dynamic a single sheet suspended in a viscous shear flow. Those original results allow verifying and comparing with numerical results^1,2).

1) S. Gravelle, C. Kamal, L. Botto J. Chem. Phys. (2020)
2) C. Kamal, S. Gravelle, L. Botto. Nat. comm. 2020