Characterisation of mixed semifluorinated alkanes Langmuir films by Grazing Incidence Small Angle X-ray Scattering and Grazing Incidence X-r

The formation of semi-fluorinated alkanes (FnHm diblocks) stable Langmuir films has been known for decades, but their structure at the nanoscale has been only recently elucidated. FnHm diblocks self-assemble at the air-water interface into regular, monodisperse arrays of hexagonally-packed hemimicelles 25 nm to 40 nm in diameter, depending on the chain length, as probed by GISAXS and GIXD. We study mixed binary films of different F8Hm (m between 14 and 20). From thermodynamic measurements, the films might comprise either a segregation of pure hemimicelles, either a mixture of pure or mixed hemimicelles. We intend to perform GISAXS and GIXD experiments to elucidate the structure of the mixed films and determine the intra- and intermicellar structure of the mixed monolayer, towards a better understanding of, and thus ultimately controlling, the mechanism of formation and self-assembly of the hemimicelles.