Stripelike domains of Langmuir monolayers formed by surfactants with partially fluorinated lipid anchors (F-alkyl lipids) are observed at the gas-liquid phase coexistence. The average periodicity of the stripes, measured by fluorescence microscopy, is in the micrometer range, varying between 2 and . The observed stripelike patterns are stabilized due to dipole-dipole interactions between terminal– groups. These interactions are particularly strong as compared with nonfluorinated lipids due to the low dielectric constant of the surrounding media (air). These long-range dipolar interactions tend to elongate the domains, in contrast to the line tension that tends to minimize the length of the domain boundary. This behavior should be compared with that of the lipid monolayer having alkyl chains, and which form spherical microdomains (bubbles) at the gas-liquid coexistence. The measured stripe periodicity agrees quantitatively with a theoretical model. Moreover, the reduction in line tension by adding traces of cholesterol results, as expected, in a decrease in the domain periodicity.
Stripes of partially fluorinated alkyl chains: Dipolar Langmuir monolayers
Author to whom correspondence should be addressed. Present address: Lehrstuhl für Experimentalphysik 1, Biophysics, Universität Augsburg, Universitätsstraße 1, D-86135 Augsburg, Germany. Fax: ++49-821-5983225. Electronic mail: matthias.schneider@physik.uni-augsburg.de
Author to whom correspondence should be addressed. On leave at Department of Physics and Center of Excellence, Kyoto University, Japan. Present address: Lehrstuhl für Biophysik, Technische Universität München, 85748 Garching, Germany. Fax: ++49-89-2891-2469. Electronic mail: mtanaka@ph.tum.de
Matthias F. Schneider, David Andelman, Motomu Tanaka; Stripes of partially fluorinated alkyl chains: Dipolar Langmuir monolayers. J. Chem. Phys. 1 March 2005; 122 (9): 094717. https://doi.org/10.1063/1.1858852
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