Stable films of cationic surfactants and phthalocyaninetetrasulfonate catalysts.
Films made from cationic surfactants and well-retained redox catalysts were investigated. Full loading of metal phthalocyaninetetrasulfonates (MPcTS4-) into water-insoluble dialkyldimethylammonium surfactants by ion exchange from aqueous solutions yielded coatings on electrodes that retain these catalyst ions for 1-2 weeks in electrolyte solutions. In contrast, partly loaded films lost most MPcTS4- ions in a few hours. All films showed gel-to-liquid crystal phase transitions at temperatures characteristic of surfactant bilayers. Cross-sectional views by SEM showed layers of 0.1-0.2 micron, as well as some disordered regions. Each larger layer is probably made up of stacks of many molecular bilayers. Retention of MPcTS4- ions seems related to their dimerization. Dimers of MPcTS4- associated with ammonium head groups may crosslink adjacent surfactant bilayers. The MPcTS4- ions that enhance stability in these films are also good redox catalysts.
Hu
N
N
Department of Chemistry, University of Connecticut, Storrs 06269-3060.
Howe
D J
DJ
Ahmadi
M F
MF
Rusling
J F
JF
D002151:Calorimetry; D002384:Catalysis; D004563:Electrochemistry; D007211:Indoles / Q000032:analysis; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D013501:Surface-Active Agents / Q000032:analysis*
D007211:Indoles; D013501:Surface-Active Agents; C028418:tetrasulfophthalocyanine