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Functional silica films: preparation and applications of porous films produced from waterglass

Chapman-Fortune, John Maurice; (2021) Functional silica films: preparation and applications of porous films produced from waterglass. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Waterglass is a commercially available silicate solution composed of anionic silicates with counter cations. In comparison to commonly used alkoxide sources of SiO2, these systems are fully inorganic and produced directly from natural silica sources. The objective of this work is to explore the uses and properties of functional films made from waterglass. To this end, spin or dip coating methods were used to cast these solutions onto glass and silicon wafer substrates. The as casted films were not stable, requiring heating and washing with acid to convert the alkali silicate films to SiO2. XPS, ATR, EDX and solid-state Si29 NMR were used to identify the change in the chemical speciation of these materials. After establishing the preparation procedure, porous films were made via introduction of a sacrificial template, potato starch in this example, into the waterglass solutions before casting, which was then removed via annealing. The optical and wetting properties of the porous films were measured. Addition of a TiO2 coating to the porous films and annealing, produced multifunctional films with photocatalytic, superhydrophilic and antifogging properties. In a separate synthesis thick sodium waterglass films were annealed to produce a foam which was able to support fully inorganic CsPbX3 perovskite quantum dots. The stability of the supported quantum dots was observed over time and their sensing capabilities for volatile organic solvents (acetone and formaldehyde) were evaluated. In addition to the creation of random pores with and without potato starch, polystyrene nanospheres were used to produce ordered porous systems and their properties were investigated. Finally, potassium waterglass solutions were dip coated onto stainless steel mesh and annealed. The coating enabled over 90% separation of oil-water mixtures for a range of oil-water ratios and oil densities encompassing that of crude oil.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Functional silica films: preparation and applications of porous films produced from waterglass
Event: UCL
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10140116
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