Pure and binary associating fluids near active surfaces
Nordlander, Peter J.
Doctor of Philosophy
The properties of associating fluids in contact with adsorbing surfaces are essential for the control of many processes of current industrial and scientific interest. Potential applications are diverse. Despite the need for a molecular understanding of interfacial properties, only in the past a few years have simple, accurate theories been developed for even simple fluids. Our group has developed a new density functional theory which applies the weighting from Tarazona's hard sphere density functional theory to Whertheim's bulk first-order perturbation theory to investigate inhomogeneous pure associating fluids confined between hard walls. This theory has been shown to be in good agreement with computer simulation results. In this work, we extend this promising theory to binary mixtures of hard spheres and associating fluids, and apply the mixture theory to non-additive hard spheres. We have accurately predicted phase separation, critical temperature and structural properties for this model. We then extend this theory to describe the properties of associating fluids near active surfaces. Metropolis Monte Carlo computer simulations are performed for one-sited (dimerizing), two-sited (linear chain forming) and four-sited (cluster forming) molecules near active surfaces. Our theory compares favorably with simulation results for a wide range of fluid density and bonding energy for surface coverage, density profiles and faction of monomers.