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Title: Molecular modelling of stimuli responsive gate effects in flexible metal organic frameworks
Author: Tam, Benjamin
ISNI:       0000 0004 7964 8933
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Metal-Organic Frameworks (MOFs) are new remarkable nano-porous materials that exhibit exceptional thermal and chemical stabilities. They have a broad range of applications ranging from, not limited to, gas storage/separation, molecular separations, sensor, catalysis, drug delivery and removal of toxic chemicals and detoxification of warfare agents. The properties of the materials are highly dependent on the nature of the atomic interactions and structural arrangement of the crystallise material. This thesis focused on the MOFs that respond to stimuli where the structure will undergo reversible transformation in which it can lead to remarkable sorption properties that enhance the material performance. The selected MOFs, ZIF-8 and Mg-MOF-74 were studied in this thesis. The materials were evaluated at atomistic and quantum levels. Here, we proposed a new theoretical concept regarding controlling molecular movements by implanting molecular machines in Mg-MOF-74. We designed the molecular machines to respond to external electric field and the machines are anchored within the onedimensional pore channel of Mg-MOF-74. The pore opening and closing was simultaneously controlled by the induced electric field; thus, the flow directions of methane can be controlled at molecular level. Moreover, this thesis moved onto the study regarding mechanical 'gate' opening movements in ZIF-8 which are stimulated by introduction of water molecules to the system. First, we examined with water models response in ZIF-8. Five types of different water models and six different ZIF-8 force fields were chosen and simulated with Grand Canonical Monte Carlo method. We found that the simulated adsorption isotherms are significant diverse in relation to water models. Afterward, we mimicked experimental water adsorption set up through the use of a graphene piston in molecular dynamics simulation. Here, we demonstrated through the use of water that we witnessed experimental 'gate' effect. However, we also found that current atomics force fields in literature were unable to replicate the adsorption isotherm at experimental conditions, resulting in the development and modifications for new force field that tune to water responses in ZIF-8.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available