Bending and interlayer shear moduli of ultrathin boron nitride nanosheet

We investigate the bending rigidity of ultrathin hexagonal boron nitride nanosheet (BNNS) through quantifying its self-folded conformations on flat substrates by using atomic force microscopy and atomistic simulations. The bending stiffness of two to six layers of BNNS is found to follow a power function of its thickness with a power index of ∼2.35 and is substantially higher than that of comparable graphene. In contrast, monolayer graphene possesses a higher stiffness than its h-BN counterpart. We attribute the high bending stiffness of multilayer BNNS to its partially ionic B-N bondings and corrugated electronic structures, which result in one order of magnitude stronger interlayer shear interaction in h-BN than in graphene. The higher out-of-plane bending and interlayer shear rigidities suggest that unlike graphene, BNNS is less prone to interlayer delamination-induced structural inhomogeneities (e.g. shearing, rippling and kinks) and thus is suitable as a building block for atomically thin electronics and a reinforcing filler for nanocomposites.