UBC Theses and Dissertations
Transport in ion dense media and recyclable polymers Petel, Yael
In order to guide the development of innovative materials and their applications, a better understanding of the mechanisms that drive their unique properties is necessary. It has been widely observed that the well-established theory of driven and self-diffusion in highly diluted solutions does not directly apply to higher concentrations. The deviation from the existing theory of transport in high concentration materials is responsible, in part, for some interesting phenomena that present opportunities for innovative applications. Due to a limited number of direct measurement techniques, the mechanisms behind these phenomena remain unknown. In this dissertation, nuclear magnetic resonance (NMR) is deployed as a tool to track the migration of magnetically visible species in complex systems. We track the transport of chromophores in electro-optical devices that can change their light-transmission properties with the application of voltage. We investigate room temperature ionic liquids and electrolyte salts in piezoionic materials, which are the basis for artificial nerves and muscles. Finally, we explore the initiating factors of crosslinker diffusion in vitrimers, a class of polymers that presents an opportunity for truly recyclable plastics. We use the well-established technique of pulsed field gradient NMR (PFG-NMR) to measure self-diffusion and extend our measurements to electrophoretic mobility by using a new, low-cost, home-built electrophoretic NMR (eNMR) probe. eNMR development still faces a variety of application challenges. We overcome some of them by setting the driven diffusion in a direction perpendicular to the majority of undesired flows such as convection currents or bubbles. Using this new probe, we successfully measure electrophoretic mobilities of individual ions which accurately predict conductivities in concentrated solutions. By measuring both driven and self-diffusion in a variety of materials, we explain some of the transport mechanisms that are behind unique material behaviours. In all the systems investigated, we find that some interaction between the ions, solvent, polymer, or a combination of the three, create interesting phenomena that alter the description of diffusion and mobility from known theory.
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