Irreversible Adsorption from Solution

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This project is in the area of analytical and surface chemistry and in the subfield of interfacial processes. The thrust of this experimental program is the testing of recently developed theoretical models which provide explication of the fundamental molecular interactions that underlie irreversible adsorption from solution. The adsorption of molecules from solution onto a surface is said to be reversible when the kinetics of the adsorption and desorption processes are comparable. In systems where irreversible adsorption is observed, the kinetics of desorption are significantly slower than the kinetics of adsorption. This implies that molecular-level changes take place in the adsorbed layer subsequent to adsorption; such implication has significant fundamental and applied importance. Infrared and photoexcited emission spectroscopy will be used to study both the structures of irreversibly adsorbed layers and the kinetics of their formation and dissolution. Additionally, surface ellipsometry will be employed for fast kinetic studies that are necessary to follow the surface phase change that converts reversible to irreversible behavior. Studies of the effects of pressure and solution conditions and also of substrate composition on adsorption behavior will be pursued to help to define the molecular details of these interfacial processes. This important but largely unexplored phenomenon of irreversible adsorption is important not only to an enhanced understanding of fundamental molecular interactions at interfaces, but also to technologically important areas such as tertiary oil recovery, surface lubrication and wear, photocatalysis, and the interaction of implantable prosthetic devices with their in vivo environments.