Title

Surfactant media for chemical applications: Fundamental studies of electrocatalytic phthalocyanine/surfactant films and micellar chromatography

Date of Completion

January 1996

Keywords

Chemistry, Physical|Engineering, Chemical

Degree

Ph.D.

Abstract

This doctoral research involved fundamental studies of electrochemistry and chromatography in organized surfactant media. The first study compared chromatographically determined surfactant-solute binding constants with those obtained using microelectrode voltammetry. The chemical system investigated consisted of ferrocene derivatives partitioned between bulk water and sodium dodecylsulfate micelles. Solute/micelle binding constants were obtained by fitting chromatographic and electrochemical data to different theoretical models. The so-called "surface binding" and "pseudophase" models of solute partitioning were shown to be special cases of a more general "monodisperse ligand binding" model. This ligand binding model gave satisfactory fits to micellar chromatographic data. Electrochemical results, however, were not satisfactorily described, possibly due to inadequacy of the assumption of simple diffusion control. An ancillary micellar chromatographic study investigated the equilibration rate of chromatographic systems after changes in eluant micelle concentration.^ The second study involved the synthesis and characterization of composite surfactant/catalyst film coated electrodes for organohalide reductions. Specifically, the catalysts, copper phthalocyanine tetrasulfonate and cobalt phthalocyanine tetrasulfonate, were incorporated into didodecyldimethylammonium bromide (DDAB) surfactant films. Structural changes induced by exchange of MPCTS$\sp{-4}$ (metal phthalocyanine tetrasulfonate, M = Cu(II) or Co(II)) for Br$\sp{-}$ in liquid crystalline DDAB were studied by DSC, FTIR, UV/VIS, optical microscopy and electrochemical methods. Data suggests that progressive loss of liquid crystallinity accompanies increased MPCTS$\sp{-4}$ concentration. Pure CuPCTS(DDA)$\sb4$ and CoPCTS(DDA)$\sb4$ show no signs of liquid crystallinity from 0-300$\sp\circ$C. In the presence of excess DDAB, the hydrated composites are liquid crystalline above 15$\sp\circ$C. These composites are catalytically active in the reduction of ethylene dibromide. ^