Molecular dynamics simulation of interface-mediated GO-GO interaction at the air-water interface

ZB Zhou and ZJ Xu and XN Yang, JOURNAL OF MOLECULAR LIQUIDS, 291, UNSP 111340 (2019).

DOI: 10.1016/j.molliq.2019.111340

Developing self-assembly of two-dimensional GO nanosheets at the air- liquid interface requires the knowledge of how interfaces affect the effective GO-GO interaction. In this work, we use molecular dynamics simulation to compute the potentials of mean force between two GO sheets in the vicinity of the air-water interface. Our simulation result shows that the thermodynamic interaction between GOs is enhanced in the interface, suggesting that GO aggregation at the air-liquid interface is more favorable than that in the bulk. The air-water interface environment can lead to reduced repulsive solvent-induced solvation force, and, more specifically, decreases the interlayer solvent effect, as compared with the bulk water phase. It is further found that GO sheets with different oxidation degrees demonstrate diverse colloidal kinetics stability in the interface. In particular, GO sheets with high oxidation degree exhibit similar stability both at the interface and in the bulk phase, which is attributed to the enhanced hydrogen-bonding interaction between interlayer water molecules and oxygen functional groups. The interface-mediated GO-GO interaction, revealed in this work, provides new insight into the effect of the air-water interface on the self-assembly processes of two-dimensional GO nanosheets. (C) 2019 Elsevier B.V. All rights reserved.

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