DOI
https://doi.org/10.25772/5A9N-YY76
Author ORCID Identifier
https://orcid.org/0000-0002-7674-5346
Defense Date
2023
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Chemical and Life Science Engineering
First Advisor
James K. Ferri
Abstract
The study of multiphase formulations is a difficult task due to inhomogene- ity. Typical methods of study, such as microscopy, suffer from sampling drawbacks and are ill-equipped at probing the system in its native state. Additionally, more concentrated sys- tems, including optically-dense emulsions and suspensions, render common light-scattering techniques, such as dynamic light scattering (DLS), useless. Lastly, macroscopic phase track- ing or transmission intensity techniques can only obtain partial information about a system. Herein, the use of diffusing wave spectroscopy (DWS), a multiple scattering adjunct to DLS, to study optically dense multiphase systems is explored. Three different systems are exam- ined, including concentrated suspensions, emulsions, and ab initio emulsion polymerization. Novel improvements on the data handling workflow, from measurement to extracted physi- cal parameters, are shown to yield accurate particle sizing estimates in highly concentrated suspensions for multiple particle types. Additionally, mechanistic understanding of ageing processes in engine-oil lubrication emulsions is presented for multiple interfacial stabilizing additives. Key results include the role of coalescence on longer term stability and surface activity of additives. Finally, DWS is applied to study the time evolution of an emul- sion polymerization system, where the concentration of droplet and particle populations are dynamically changing with complex kinetics. The results presented show that DWS can suc- cessfully be applied to study a range of multiphase formulations with a variety of industrial use cases.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
9-19-2023