Prediction of strain-controlled adhesion in a single-layer covalent organic framework

MY Suarez-Villagran and T Botari and JH Miller and LD Machado, CARBON, 143, 172-178 (2019).

DOI: 10.1016/j.carbon.2018.11.002

Recent research has revealed that strain can be used to control electronic properties, thermal conductivity, and permeability in two- dimensional (2D) materials. The use of deformation to tune physical properties is often termed strain engineering, and applications in photoelectronics and gas separation have been proposed. In the present contribution, we employ reactive molecular dynamics to show that strain can also be used to tune adhesion in a porous 2D covalent organic framework (COF-1). In our simulations, we apply uniaxial strain to single-layers of COF-1, and use a graphene monolayer to measure work of adhesion values. Our results show that strain forces COF-1 to assume a non-planar configuration, decreasing the effective contact area with graphene and, consequently, the adhesion - by more than 25%. This reduced 'stickyness' can be reversed, simply by removing the external strain. We then present a proof-of-concept simulation, where we apply strain-controlled adhesion to transfer a graphene membrane between substrates. Finally, we characterize the mechanical properties of COF-1 under uniaxial strain. (C) 2018 Elsevier Ltd. All rights reserved.

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