title: Long-range nanometer-scale organization of semifluorinated alkane monolayers at the air/water interface.
abstract: We have determined the structure formed at the air-water interface by semifluorinated alkanes (C(8)F(17)C(m)H(2m+1) diblocks, F8Hm for short) for different lengths of the molecule (m = 14, 16, 18, 20) by using surface pressure versus area per molecule isotherms, Brewster angle microscopy (BAM), and grazing incidence x-ray experiments (GISAXS and GIXD). The behavior of the monolayers of diblocks under compression is mainly characterized by a phase transition from a low-density phase to a condensed phase. The nonzero surface pressure phase is crystalline and exhibits two hexagonal lattices at two different scales: a long-range-order lattice of a few tens of nanometers lateral parameter and a molecular array of about 0.6 nm parameter. The extent of this organization is sufficiently large to impact larger scale behavior. Analysis of the various compressibilities evidences the presence of non organized molecules in the monolayer for all 2D pressures. At room temperature, the self-assembled structure appears generic for all the F8Hm investigated.
authors: Institut des Nano Sciences de Paris, UMR 7588 CNRS, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France.
authors: Lisa
authors: L
authors: Bardin
authors: Marie-Claude
authors: MC
authors: Fauré
authors: Denis
authors: D
authors: Limagne
authors: Corinne
authors: C
authors: Chevallard
authors: Oleg
authors: O
authors: Konovalov
authors: Eduardo J M
authors: EJ
authors: Filipe
authors: Gilles
authors: G
authors: Waton
authors: Marie Pierre
authors: MP
authors: Krafft
authors: Michel
authors: M
authors: Goldmann
authors: Philippe
authors: P
authors: Fontaine
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D012542:Scattering, Radiation; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000473:Alkanes; D013501:Surface-Active Agents; D005461:Fluorine