Molecular Dynamics study of the effect on the interfacial activity of Alkylamine-Modified graphene oxide

BA Arenas-Blanco and L Munoz-Rugeles and R Cabanzo-Hernandez and E Mejia-Ospino, JOURNAL OF MOLECULAR LIQUIDS, 362, 119724 (2022).

DOI: 10.1016/j.molliq.2022.119724

Several experimental studies have shown that chemical modification of graphene oxide with n-alkylamines allow to control its interfacial activity in oil-water systems, altering its dispersibility and favoring the formation of emulsions. However, due to the complexity of its chemical structure and exper-imental limitations, the emulsification mechanism and interfacial properties have not been fully under-stood. In order to understand the behavior at the oil-water interface of alkylamine functionalized Graphene Oxide (GO) based materials, in this research we evaluated the interfacial activity of GO func-tionalized with different alkylamines (aGO) with different aliphatic chain lengths of 1, 3, 5, 7, 9 and 12 carbon atoms by Molecular Dynamics simulations. The dispersibility of the GO-based materials was ana-lyzed and it was found that the Hydrophilic-Lipophilic Balance (HLB) of the GO can be controlled with the alkylamine chain length, making the GO more hydrophobic as the aliphatic chain length of the alkylami-nes becomes longer. Alkylamine chains bonded on the GO structure were capable to modifying the ori-entation relative to the Toluene/Water interface, going from parallel for the GO case to orthogonal for the aGO nanosheets, adopting a "head-tail" configuration due to the hydrophobic effect between the alipha-tic chains and the Water molecules. Simulations also revealed that synergistic effect of aGO can decrease the interfacial tension of the Toluene-Water system as the aliphatic chain length and number of sheets increase obeying the Traubes rule, indicating a behavior like molecular surfactant, where the IFT of the system decreases as the amount of surfactant increases. (c) 2022 Elsevier B.V. All rights reserved.

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