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UBC Theses and Dissertations

Development of methods for studying the rheology of interfaces and microparticles Huang, Yun-Han


The rheological characterization of interfaces and microparticles is important in various applications. For instance, interfacial rheology of aveoli plays a vital role in the diagnosis and treatment of respiratory diseases or damage. The rheology of viscoelastic microcapsules is also significant in drug delivery and predicting deformation behaviors through capillaries and digestive tracts. Furthermore, the interfacial rheology of oil-water interfaces is also important in the processing of wastewater and cleaning up oil spills. This dissertation develops methods for characterizing the rheology of interfaces and microparticles, including a new instrument for interfacial dilational rheology and mathematical models for several microparticles. This dissertation aims to contribute to the field by improving the methods of rheological characterization from the aspects of measurement techniques and mathematical models. We approached this by introducing a new instrument for characterizing the dilational rheology of air-liquid interfaces, which includes a mechanism of deformation that is different from existing techniques. The validation the interfacial dilational rheometer was done by frequency sweep measurements with soluble surfactants, and we also demonstrated integrating the design with a Langmuir trough. In terms of improving the models, we study the viscoelasticity of gellan-gum microcapsules and proposed a simple but effective mathematical models for relating the overall modulus of core-shell microcapsule with their shell modulus. We also present a work on characterizing the viscoelasticity of neurospheres, where we observede size-dependent elastic moduli of them. Our findings further suggest that the trends between elastic moduli and the size of tissue remain the same for the treated and untreated group. Therefore, it would be an incorrect oversimplification to take average of moduli for neurospheres with various sizes and claim that there is a significant difference in moduli among the two groups. The findings along with the developed instrument in this dissertation can serve as useful tools and guidelines for future studies of the rheological characterization of interfaces and microparticles.

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