Selective incorporation of dyes with fluorocarbon and hydrocarbon chains into coexisting micellar phases of sodium perfluorooctanoate and dimethyl tetradecyl aminoixde

Abstract

Abstract

Solutions of sodium perfluorooctanoate (SPFO) and dimethyl tetradecyl aminoxide (TDMAO) show a miscibility gap which can be determined by surface tension measurements. Within this demixing region, the initially clear viscous solutions are metastable and split after some weeks into two phases of which the lower one is very turbid and contains a lamellar phase.

In metastable solutions, two kinds of micelles coexist. This is shown by contrast variation in light scattering using water-glycerol mixtures. The necessary premise that there is no basic difference between solutions in water and water-glyerol 50 : 50 w/w was proved by ¹⁹F-NMR measurements.

Both kinds of aggregates can be stained slectively by corresponding cyanine dyes. When phase separation occurs, the lower perfluorosurfactant-rich phase contains mainly fluorinated dye, whereas in the upper phase the normal dye is enriched. The phase separation can be accelerated by ultracentrifugation.

Coexisting micellar aggregates can be used for the spatial segregation of two photosystems which are necessary to drive photolytic water splitting by a two-photon process.