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Title
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Graphene-based membranes and nanoconfined water : molecular dynamics simulation study
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Author
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Abstract
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| The primary aim of the thesis is the exploration of structural and dynamical properties of graphene-based membranes and nanoconfined water within the framework of large-scale molecular dynamics (MD) simulations. A membrane can be defined as a selective barrier that can form nanochannels able to efficiently separate specific molecules and ions. Controlled transport of water molecules through membranes and capillaries has important applications in water purification and ion sieving. MD simulation is a powerful tool that helps us to understand the underlying physics at the atomic scale of the interactions between water and graphene surfaces, that can have drastic effects. This thesis predicts, on the basis of intensive MD simulations, coupled with experimental measurements, that the shape of the graphene nanobubble can depend critically on the properties of the trapped substance such as the formation of amorphous but layered structured water bubbles caused by the extreme confinement. It provides insights into the effects of the specific material and the van der Waals pressure on the microscopic details of graphene nanobubbles. For example, nanobubbles filled with small hydrocarbons, or water, have a circular, or non-circular shape. In addition, it investigates water permeation through graphene oxide membranes, predicting a significant change in the slippage dynamics of confined water in the presence of surface functional groups. This explains the extremely strong impact of commensurability induced by nanoconfinement, on the intrinsic dynamical properties of water. We study various organic solvents intercalated in a montmorillonite clay membrane, an ionic nanochannel with interlayer metal cations. We are able to explain the solvents’ observed swelling properties and anomalous permeation, using polarity and aromaticity as fundamental mechanisms at the molecular scale. The thesis also studies nitrogen-doped monolayer graphene, predicting ripples and weaker mechanical strength due to substitutional doping. Furthermore, it proposes an alternative approach for controlling the stochastic motion of a graphene flake over a graphene substrate, by engineering topological defects in the substrate. |
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Language
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English
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Publication
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Antwerpen
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Universiteit Antwerpen, Faculteit Wetenschappen, Departement Fysica
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2019
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Volume/pages
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243 p.
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Note
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Peeters, François [Supervisor]
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Neek-Amal, Mehdi [Supervisor]
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Full text (open access)
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