Mechanical Properties of Monolayer Graphene Oxide

TLDR

The study aims to evaluate the elastic modulus and prestress of ultrathin graphene oxide membranes by combining AFM measurements with finite element modeling. The authors investigated the mechanical properties of monolayer, bilayer, and trilayer graphene oxide membranes using AFM imaging in contact mode and finite element analysis to map elastic modulus and prestress. Monolayer graphene oxide exhibits a lower effective Young's modulus (~208 GPa) and an order‑of‑magnitude lower prestress (≈40–77 MPa) than pristine or mechanically cleaved graphene, demonstrating the effectiveness of the AFM–FEM mapping approach.

Abstract

Mechanical properties of ultrathin membranes consisting of one layer, two overlapped layers, and three overlapped layers of graphene oxide platelets were investigated by atomic force microscopy (AFM) imaging in contact mode. In order to evaluate both the elastic modulus and prestress of thin membranes, the AFM measurement was combined with the finite element method (FEM) in a new approach for evaluating the mechanics of ultrathin membranes. Monolayer graphene oxide was found to have a lower effective Young's modulus (207.6 ± 23.4 GPa when a thickness of 0.7 nm is used) as compared to the value reported for "pristine" graphene. The prestress (39.7−76.8 MPa) of the graphene oxide membranes obtained by solution-based deposition was found to be 1 order of magnitude lower than that obtained by others for mechanically cleaved graphene. The novel AFM imaging and FEM-based mapping methods presented here are of general utility for obtaining the elastic modulus and prestress of thin membranes.