Effect of the Molecular Structure on the Hierarchical Self-Assembly of Semifluorinated Alkanes at the Air/Water Interface
| Autor: | C. O. Klein, Klaus Müllen, Ulrich Jonas, L. de Viguerie, Christopher G. Clark, Thomas Geue, Rüdiger Berger, Dimitris Vlassopoulos, Hans-Jürgen Butt, Rabea Keller |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Halogenation
Surface Properties Dodecane Supramolecular chemistry 02 engineering and technology 010402 general chemistry 01 natural sciences Micelle chemistry.chemical_compound Alkanes Monolayer Electrochemistry Organic chemistry General Materials Science Fluorocarbon Spectroscopy Alkane chemistry.chemical_classification Air Water Surfaces and Interfaces 021001 nanoscience & nanotechnology Condensed Matter Physics 0104 chemical sciences 3. Good health Neutron Diffraction Hydrocarbon chemistry Chemical engineering Self-assembly 0210 nano-technology |
| Zdroj: | Langmuir |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la201377f |
| Popis: | Semifluorinated alkanes (C(n)F(2n+1)C(m)H(2m+1)), short FnHm display local phase separation of mutually incompatible hydrocarbon and fluorocarbon chain moieties, which has been utilized as a structure-forming motif in supramolecular architectures. The packing of semifluorinated alkanes, nominally based on dodecyl subunits, such as perfluoro(dodecyl)dodecane (F12H12) and perfluoro(dodecyl)eicosane (F12H20), as well as a core extended analogue, 1,4-dibromo-2-((perfluoroundecyl)methoxy)-5-(dodecyloxy)benzene) (F11H1-core-H12), was studied at the air/water interface. Langmuir monolayers were investigated by means of neutron reflectivity directly at the air/water interface and scanning force microscopy after transfer to silicon wafers. Narrowly disperse surface micelles formed in all three cases; however, they were found to bear different morphologies with respect to molecular orientation and assembly dimensionality, which gives rise to different hierarchical aggregate topologies. For F12H12, micelles of ca. 30 nm in diameter, composed of several circular or "spherical cap" substructures, were observed and a monolayer model with the fluorocarbon block oriented toward air is proposed. F12H20 molecules formed larger (ca. 50 nm diameter) hexagonally shaped surface micelles that were hexagonally, densely packed, besides more elongated but tightly interlocked wormlike structures. Conversely, F11H1-core-H12 films organized into linear rows of elongated surface micelles with comparable width, but an average length of ca. 400 nm, apparently formed by antiparallel molecular packing. |
| Databáze: | OpenAIRE |
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