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Title: Elucidation of the formation of cubic mesoporous silicas
Author: Qin, Ling
ISNI:       0000 0004 2740 3002
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2013
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Four cubic mesoporous silicas, SBA-1, SBA-16, AMS-8 and AMS-10, were synthesized and the iso-electron density maps were built based on the amplitudes of structure factors recorded from SAXS and the phases retrieved from reference to HREM. A mesopore fraction to the total volume of the unit cell measured from the nitrogen adsorption was applied to identify the contour of the silica interface.Further, minimal surfaces which correspond to the space groups of the mesostructures were refined in Surface Evolver. The global mean curvatures of the surfaces were adjusted slightly to fulfill the consistent void fractions given by the gas sorption. A comparison has thereby been made between the experimental iso-electron density contours and their corresponding simulated constant-mean-curvature surfaces. A resistance of the silica interface on reducing to the constant-mean-curvature surface was found at the connections between mesocages according to the comparison. It can be concluded that the inorganic moiety undergoes a stronger affinity with the connections where water is filled than the spherical surfactant micelles.Moreover, the surfactant templates of SBA-1 and SBA-16 were removed at temperatures lower than 100 °C in order to maintain the inorganic morphology identical to the as-synthesized samples and avoid any structural shrinkage caused by calcination. The optimum method used was based on the properties of the surfactants: cationic C16TEABr was extracted by the supercritical CO2-MeOH fluid; neutral triblock PEO-PPO-PEO copolymers were broken down by O3.
Supervisor: Anderson, Michael Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available