Mississippi State University
Walters, Keisha B.
Date of Degree
Dissertation - Open Access
Doctor of Philosophy
James Worth Bagley College of Engineering
Department of Chemical Engineering
Soft materials are ubiquitous in every aspect of our daily life. These materials composed of a wide range of subfields including surfactants, foams, emulsions, pastes, slurries, polymers, gels, and colloidal suspensions. In recent years, there has been a great interest focusing on the understanding of the macroscopic properties of various types of soft materials as a function of their microstructures. For example, the structure-property relationship of physically-associating triblock copolymer gels can be controlled by selecting different types of solvents and changing the temperature. In these systems, gelation occurs due to the significant changes in the solubility of one or more of the blocks with temperature compared to the other blocks. Therefore, changing the temperature can lead to the structural transitions and macroscopic properties. The other strategy that can be used to modify the macroscopic performance of polymer gels is through the incorporation of nanoparticles, such as graphene nanoplatelets and nanotubes. The addition of nanoparticles can also affect the mechanical properties of concentrated suspensions in which, understanding the structure/flow properties is vital for processing and manufacturing of a product. Despite significant advances in the field of soft materials, our understanding in linking the structure-property relationships of polymer gels and concentrated suspensions is incomplete. With this perspective, in this dissertation, shear-rheometry and scattering techniques were used to understand the structural changes of the self-assembled triblock copolymer gels over a wide length-scale and broad temperature-range. Graphene nanoplatelets have been incorporated into this system to investigate the self-assembly behavior and mechanical properties as a function of graphene concentration. On the other hand, in concentrated suspensions of functionalized nanoparticles in a low-molecular- weight polymeric media, the effect of nanoparticles on the rheological properties were investigated. The present work provides a better understanding of the nanoparticles’contributions on microstructure and mechanical behavior of soft materials.
Zabet, Mahla, "Structure-Property Relationships of Polymer Gels and Concentrated Suspensions Modified with Anisotropic Nanoparticles" (2018). Theses and Dissertations. 4097.