Ultrahigh adhesion between carbon nanotube and free-standing monolayer graphene

Abstract

Using a self-prepared individual carbon nanotube (CNT) mechanical force sensor, we measured the adhesion between CNT and free-standing monolayer graphene and other bulk substrates. All the measurements were made by using the same CNT force sensor under the same conditions, such as moving speed, observation angle, temperature, and vacuum pressure, confirming the reliability and accuracy of experimental data. The adhesion at contact is proportional to the deformation of the curved CNT, which can be directly measured in a scanning electron microscope. It was found that the deformation of CNT was the largest on the suspended graphene, showing that the suspended graphene has the largest adhesion on CNT. This unusually high adhesion on suspended monolayer graphene is related to the low bending stiffness and extreme flexibility of this atomically thin layer. The main contribution of this work is to demonstrate the unusually high adhesion on suspended graphene experimentally. More advanced modeling needs complicated molecular dynamics simulation and surface energy computation in our future work.