Thermal expansion of surface-frozen monolayers of semifluorinated alkanes

The linear coefficient of thermal expansion of a quasi-2D surface-frozen crystalline layer is measured, using surface X-ray diffraction, for three different semifluorinated alkane diblocks. The values obtained are in good agreement with those of surface-frozen monolayers of fully protonated alkanes. An unexpected strong dependence on the protonated block's length is found and discussed.