Switching the mechanical performance of graphene oxide paper by integrating small molecules into nano-sheets

The mechanical performance o f graphene oxide (GO) paper was switched from brittle to relatively tough by integrating small molecules, such as glutaraldehyde (GA) or H2O, into the galleries between nano-sheets. X-ray photoelectron spectroscopy and Fourier-transformed infrared spectra characterizations indicated that the chemical cross-linked structure of GO paper was formed by modifying with GA. Therefore, the strain transfer efficiency of GO paper under tension was significantly improved as measured with Raman spectroscopy, which is probably due to the enhanced interaction between nano-sheets. Consequently, the modulus and strength were increased promisingly. However, this is different for H2O molecules which act as lubricants between GO layers. H2O is of help to the slippage of GO nano-sheets under external loading, which performs tough behavior of the macro-scale paper. As a result, based on the integration of GA or H2O, and even a combination of both, the tensile modulus of GO paper can be adjusted from 6.4 to 30.2 GPa, strength from 65 to 105 MPa, and elongation from 0.4 up to 2.2%. Creep test further confirmed that the mechanical performance of GO paper can be switched due to these small molecules wh ich affect the interactions between nano-sheets.EI