Abstract
The self-assembly of materials is known to have a strong impact on their properties such as diffusion, opacity, viscosity and reactivity. Lipids are a class of material that is known to self-assemble and to exhibit rich polymorphism in the phases that are adopted. These phases are known to be concentration dependent and to vary with water content.Aerosols are found across a wide range of applications. They are used in industry with spray drying, in drug delivery to the lungs and are present in the atmosphere. Many aerosols contain lipidic components which are known to self-assemble in solution. Despite this, there is little understanding of the self-assembly of lipids within aerosols, and where this research has been carried out is has focused on urban pollutants such as cooking emissions.
This thesis aims to further our understanding of the self-assembly of lipids in aerosols. To do this, we develop new techniques such as the simultaneous combination of Quartz Crystal Microbalance with Grazing Incidence Small Angle X-ray Scattering in a humidity-controlled environment, adapt existing techniques to the study of levitated lipids with X-ray diffraction techniques such as acoustic or electrodynamic levitation. We also study aerosols offline by collecting them on droplets conditioned in a Falling Droplet Column on a substrate and using imaging techniques to understand their morphology.
We show that deep lung respiratory aerosol proxies self-assemble into lamellar phases under ambient conditions, both as thin films and levitated droplets. We demonstrate the power of our developed techniques in accelerating previous research into phase diagrams and sorption isotherms and in making X-ray diffraction analysis of levitated droplets more accessible. We study the effect of relative humidity and concentration on the morphology and phase of D-mannitol, and, finally, we develop a model for the neutralisation of charged aerosol droplets due to exposure to X-ray radiation.
| Date of Award | 11 Dec 2024 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Adam Squires (Supervisor) & Bernardo Castro Dominguez (Supervisor) |