SYNTHESIS, CHARACTERIZATION AND APPLICATIONS OF AZO-CONTAINING PHOTODESTRUCTIBLE SURFACTANTS

Photodestructible surfactants, sodium 4-(2-cyano-2-undecylazo)benzoate and a series of sodium 4-alkylphenylazosulfonates, have been synthesi zed and were shown to be surface active in solution, each exhibiting a distinct critical micelle concentration (CMC). UV irradiation of aque ous solutions of the alkylazobenzoate led to a distinct increase in su rface tension, but even after complete photolysis significant surface activity remained, indicating a substantial amount of cage recombinati on after nitrogen evolution. UV irradiation of sodium 4-dodecylazosulf onate caused a photoscission reaction, completely destroying its surfa ce active properties. In the case of azosulfonates with shorter alkyl chains, however, some residual surface activity remained after complet e removal of the azo linkage, indicating that secondary surfactants we re formed by the photolysis. The 4-alkylphenylazosulfonates were able to solubilize an oil-soluble dye in water to produce isotropic coloure d solutions. Photoirradiation of these solutions led to complete-loss of colour, presumably as a result of microprecipitation of the dye. Th e azosulfonate surfactants also-readily emulsified vinyl monomers, suc h as styrene, in water. Attempts to achieve emulsion polymerization le d to only low conversion of monomer, most likely owing to side reactio ns between initiating radicals and the azo linkage of the surfactant, leading in turn to disruption of the micelle.