Fundamental and applied studies of polyaniline: Gas separations, Donnan phenomena, and nonlinear optics.

摘要

Conjugated polymers have been studied by others for their potential utility as replacements for metal in certain electrical applications. The problem with these materials centers on the fact that they are difficult to process and lack the requisite environmental stability. This dissertation presents the results of studies on the conjugated polymer polyaniline which is found to be both environmentally stable and processible.;Polyaniline is environmentally stable when synthesized in the emeraldine oxidation state. A procedure for producing high quality fully dense films has been developed. This was achieved by increasing the solubility of the nascent polymer in aprotic polar solvents such as NMP. These films have been studied by routine polymer characterization techniques. They compare favorably to other useful polymeric engineering materials. The physical and morphological properties of these films can be controlled by doping with a wide variety protonic or Lewis acids.;Polyaniline membranes may find use as anion exchange membranes. Doped emeraldine membranes display a rather unusual Donnan phenomenon. Doping studies from aqueous HCl and HCl + NaCl solutions have enabled the development of theory which accounts for this behavior. Further electrochemical studies have allowed for the first direct measurement of charge on the double layer between a solid-liquid interface.;Polyaniline membranes have very extraordinary properties with respect to the separation of mixtures of gases. Permeability studies have shown that the doping process can be exploited to selectively tailor the morphology of the films to optimize the separation of commercially important mixtures of gases such as oxygen and nitrogen from air, and carbon dioxide from methane in natural gas.;A model system for the incorporation of conjugated polymers into inorganic glass via sol-gel techniques has been developed. Robust monoliths and thin films of these have been produced and characterized. These have been evaluated by degenerate four wave mixing spectroscopic techniques (DFWM) to determine the magnitude of the third order polarizability effects for non-linear optical (NLO) applications.