Interface Adhesion between 2D Materials and Elastomers Measured by Buckle Delaminations

2D systems have great promise as next generation electronic materials but require intimate knowledge of their interactions with their neighbors for device fabrication and mechanical manipulation. Although adhesion between 2D materials and stiff substrates such as silicon and copper has been measured, adhesion between 2D materials and soft polymer substrates remains difficult to characterize due to the large deformability of the polymer substrates. In this work, a buckling-based metrology for measuring the adhesion energy between few layer molybdenum disulfide (MoS2) and soft elastomeric substrates is proposed and demonstrated. Due to large elastic mismatch, few layer MoS2 flakes can form spontaneous wrinkles and buckle-delaminations on elastomer substrates during exfoliation. MoS2-elastomer interface toughness can therefore be calculated from the buckle delamination profile measured by atomic force microscopy. The thickness of the MoS2 flake is obtained by analyzing coexisting wrinkles on the same flake. Using this approach, adhesion of few layer MoS2 to 10:1 Sylgard 184 polydimethylsiloxane is measured to be 18 +/- 2 mJ m(-2), which is about an order of magnitude below graphene-to-stiff-substrate adhesion. Finally, this simple methodology can be generalized to obtain adhesion energies between various combinations of 2D materials and deformable substrates.