Ultrastrong adhesion of graphene membranes. Nat Nano 6

As mechanical structures enter the nanoscale regime, the influ-ence of van der Waals forces increases. Graphene is attractive for nanomechanical systems1,2 because its Young’s modulus and strength are both intrinsically high, but the mechanical behaviour of graphene is also strongly influenced by the van der Waals force3,4. For example, this force clamps graphene samples to substrates, and also holds together the individual gra-phene sheets in multilayer samples. Here we use a pressurized blister test to directly measure the adhesion energy of graphene sheets with a silicon oxide substrate. We find an adhesion energy of 0.45+0.02 J m22 for monolayer graphene and 0.31+0.03 J m22 for samples containing two to five gra-phene sheets. These values are larger than the adhesion energies measured in typical micromechanical structures and are compar-able to solid–liquid adhesion energies5–7. We attribute this to th