Gels of semifluorinated alkanes: Structural investigations by small angle x-ray scattering

The gels of perfluorododecylalkanes F12Hn in dodecane were investigated wit h small angle x-ray scattering (SAXS). These gels can be categorised into t hree groups according to their stability and optical appearance. The short chain samples with n less than or equal to 6 form highly turbid gels which eventually undergo a phase separation, the samples with 8 less than or equa l to n less than or equal to 12 form opaque stable gels and the long chain homologues form stable gels which are transparent. This categorisation is a lso reflected in the SAXS patterns which show that the F12H6 gel has a mono layered lamellar structure, while the SAXS data from the gels with 8 less t han or equal to n less than or equal to 12 have to be interpreted in terms of double layered undulating stacks. The structure of the gels formed by th e long chain members could not be clarified yet.