Gels are colloidal states of matter in which a solid matrix is dispersed in a liquid phase. Supramolecular gels are formed due to the self-assembly of small gelator molecules in a suitable solvent as a result of specific weak non-covalent interactions between the gelators. The last several decades have witnessed an upsurge in research activities in the area of supramolecular gels not only for academic interests but also for applications in material science. Gels have been investigated as potential avenues for drug delivery and oil recovery applications. Despite their huge potential, the properties of gels are discovered through trial-and-error approaches, which makes control of properties a challenging task. The control becomes extremely hard in a multicomponent gel system, which is a common model for applications in material science.
The aim of this thesis is to design a pathway to gain a fundamental understanding on how multiple components in the gel contribute to new properties. This pathway is an attempt to move away from trial-and-error approaches for the development of gels and allows us to make correlations between structure, dynamics and function.
The studies reported in this thesis were performed on a two-component gel system comprising a gelator and an additive. The gelator, sodium deoxycholate (NaDC), is a bile salt known for its ability to form a supramolecular gel within a certain pH range. NaDC gels are made up of aggregates distributed between the aqueous phase and the gel structure. NaDC gels are reversible and considered as promising candidates from a functional point of view. The additive, cucurbit[6]uril (CB[6]), is a macrocycle and is known to affect the mechanical properties of NaDC gels at the macroscopic level.
In the first project, I studied the effect of CB[6] on the NaDC gel at the microscopic level using dynamic light scattering and fluorescence microscopy experiments. These techniques were used to determine the effect of CB[6] on the gel’s morphology, size of NaDC aggregates, thermo-reversible properties of NaDC gels and the kinetics of NaDC gel formation. My results showed that the effect of CB[6] on NaDC aggregates begins in solutions and is translated to sols and gels. Thermo-reversibility and kinetic studies showed that the effect of CB[6] on NaDC gels goes beyond changes to the gel’s structure and CB[6] was also shown to affect both the gel-sol transition temperatures and time of the gel formation.
In the second project, I studied how the release of dyes of different hydrophobicities from NaDC gels was affected by the addition of CB[6]. The release of the dyes pyrene and rhodamine 6G was investigated using a static diffusion method, which was referred to as the top layer method. My results showed that CB[6] has a different effect on the release kinetics of a hydrophilic dye compared to the release of a hydrophobic dye. The observed difference in the release kinetics was attributed to differences in the localization of the dyes in NaDC gels and the role of CB[6] in affecting the distribution of dyes in different regions in the gel.
In the third project, I studied the colocalization of a hydrophobic and a hydrophilic dye in NaDC-CB[6] gels with the goal to confirm my hypothesis from the release studies. Dynamics of diffusion of dyes within NaDC-CB[6] gels was investigated using the fluorescence recovery after photobleaching (FRAP) technique. Results from colocalization experiments showed that the addition of CB[6] changes the distribution of hydrophilic dye in the gel. Through colocalization experiments, I was able to showcase the active role of CB[6] in incorporating aggregates from the aqueous phase into the gel structure. Results from FRAP studies showed that, in the presence of CB[6], recovery after bleaching of a hydrophobic dye in the gel structure is slower compared to the dye in the NaDC gel structure. / Graduate
Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/13847 |
Date | 04 April 2022 |
Creators | Talluri, Sree Gayathri |
Contributors | Bohne, Cornelia |
Source Sets | University of Victoria |
Language | English, English |
Detected Language | English |
Type | Thesis |
Format | application/pdf |
Rights | Available to the World Wide Web |
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