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Title: Simulation studies of surface and bulk properties of materials
Author: Ojo, Sonia
ISNI:       0000 0001 3455 6902
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2002
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This thesis addresses three related problems of substantial interest in contemporary Chemistry: first, crystal growth inhibition; second, molecular diffusion in microporous materials and third, the interaction of sucrose at the ice-water interface which is of importance in the development of commercial ice-cream. The crystal growth studies have involved the utilisation of robust modelling methodologies which included energy minimisation and molecular dynamics methods. The mode of interaction of a selection of newly designed phosphonate crystal inhibitors was modelled in order to elucidate their mode of interaction with respect to the stepped and planar {1014} planes of calcite. The phosphonates were chosen to elucidate the variation in their activity as a function of structure. It has also been shown in this study that; a) poisons have a greater affinity for the defect containing surfaces compared to planar surfaces in accordance with experimental observations; b) the presence of a hydrophobic functional group depletes poison efficacy; c) the presence of electronegative atoms promotes the operation of the poison; d) the diphosphonate HEDP is a superior poison to monophosphonate species. The mechanism of action for these phosphonates is proposed. Insights into long-range molecular diffusion have been investigated in the purely siliceous form of Faujasite and CIT-1 zeolites. Atomistic simulation studies involving the diffusion routes of molecules and the calculation of diffusion coefficients, obtained from the Einstein relation, have been undertaken for the rigid ion and shell model descriptions of the zeolites using NVT, NVE and NPT simulation protocols. Inclusion of oxygen polarizability via the shell model gives rise to decreased calculated diffusion coefficients as well as enhanced molecular contact with the zeolite channel walls, in contrast to the rigid ion model. In appendix A, a representation of the ice-water interface has been produced enabling the favourable sucrose interaction modes to be predicted.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available