Investigation of graphene oxide nanosheets dispersion in water based on solubility parameters: a molecular dynamics simulation study
EK Goharshadi and G Akhlamadi and SJ Mahdizadeh, RSC ADVANCES, 5, 106421-106430 (2015).
In this work, the dispersion behavior of graphene oxide (GO) nanosheets in water was studied by a series of MD simulations for water, GO, and the water/GO mixed systems. The simulation results showed that the water/GO system has a well-ordered structure with strong H-bond interactions. The initial value (4.0 angstrom) of the interlayer distance between two GO sheets at the beginning of the simulation clearly increased (similar to 7.2 angstrom) in the presence of water as compared to its value after simulation in the absence of water (5.7 angstrom). The solubility parameter of GO was calculated as a function of both temperature and number of layers. The solubility parameter of GO at 300 K reached a plateau at 44.9 MPa1/2 when the number of layers was five. Hence, water is a good solvent for dispersing GO since their solubility parameters are close to each other especially at temperatures close to the freezing point of water. The strong H-bond between water and oxygen-functional groups of GO makes the enthalpy favorable to form stable GO dispersions in water.
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