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Title: Classical and ReaxFF molecular dynamics simulations of fuel additives at the solid-fluid interface
Author: Chia, Chung Lim
ISNI:       0000 0004 7657 967X
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2019
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In the automotive industry, a kind of fuel additives, known as surfactant, is used to protect metallic surfaces. Its efficiency strongly depends on factors such as temperature, solvent properties and the presence of other surfactants in the system. In this thesis, both classical and ReaxFF molecular dynamics (MD) simulations are used in studying the impacts of these factors on the adsorption of organic surfactants at the fluid-solid interface. Firstly, a classical MD simulation study of competitive adsorption is carried out on a multi-functional phenol and amine surfactant model with ethanol at the oil/iron oxide interface. As the concentration of ethanol increases, the ethanol molecules effectively compete for the adsorption sites on the iron oxide surface. This observation concurs with the experimental findings of similar oil/iron oxide systems. Unlike most MD interfacial studies, ReaxFF MD uses a fully flexible and polarizable solid surface. The second part of the thesis includes a study on the effect of polarity of organic molecules on the structure of iron oxide using ReaxFF-based MD simulations. The simulation results suggest that care must be taken when parameterising empirical and transferable force fields because the fixed charges on a solid slab may not be a perfect representation of the real system, especially when the solid is in contact with polar compounds. Lastly, but not the least, missing ReaxFF interaction parameters for Fe/N have been developed to simulate the adsorption of amine based surfactant on iron oxide. The parameterisation of the force field is done by fitting these interaction parameters to a set of quantum mechanical data involving iron-based clusters. These newly developed parameters are able to capture chemisorption and proton transfer between hexadecylamine and iron oxide.
Supervisor: Siperstein, Flor ; Avendano Jimenez, Carlos Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Computational Chemistry ; Molecular Dynamics ; Force Field Parameterisation ; Fuel Additive ; Surfactant