Theoretical Modeling of Interactions Between Electrolytes and Surfaces

Electrolytes are ubiquitous in science and engineering and are of active interest, owing to their applications biology, energy storage, colloidal suspensions, and even climate. Near a surface, electrolyte solutions exhibit a plethora of rich thermodynamic and structural phenomena, owing to the interplay of long-ranged electrostatics and nonelectrostatic interactions between ionic species, solvent, and the surface. In this thesis, we present a pedagogical formulation for the thermodynamics of electrolyte solutions near charged surfaces, followed by an examination of interactions and structure of different types of electrolytes near surfaces. Specifically, we investigate the difference between constant surface charge and constant surface potential boundaries in electrolyte solutions, the capacitance applications, double-layer structure, and screening behavior of a zwitterionic polymers, as well as the effect of image charge on structure, capacitance, and forces in simple electrolytes near metal, dielectric, and dielectrically-saturated metal surfaces. We conclude with a Gaussian-fluctuation model for ions with soft-core excluded volume interactions.