Aggregation behavior of a semifluorinated n-alkane in perfluorooctane

The phase behavior of solutions of two semifluorinated n-alkanes, heptadecafluorotetracosane (F(CF2)8(CH2)16H) and pentacosafluorooctacosane (F(CF2)12(CH2)16H), in perfluorooctane and isooctane is studied. Viscosity, dynamic light-scattering, and small-angle neutron-scattering data show the presence of small, nearly spherical aggregates in heptadecafluorotetracosane/perfluorooctane solutions in the liquid phase above the critical micelle concentration. We determined the size and average aggregation number of these aggregates as a function of the fluorohydrocarbon concentration. Small-angle neutron-scattering results show that the perfluorooctane solvent penetrates appreciably into the micellar core.