Mechanical properties of giant folds in a Langmuir monolayer

ORAL

Abstract

We study the mechanical properties of giant folds in a catanionic monolayer at the air water interface. The system of study is a dioctadecyldimethylammonium bromide (DODAB) and sodium dodecyl sulfate (SDS) monolayer which folds upon compression in a Langmuir trough. Carboxylate-coated polystyrene beads (1~micron~diameter) are attached to the monolayer in order to track its displacement with epifluorescence microscopy and particle image velocimetry. This analysis yields a measurement of the velocity of the monolayer around the fold. The quantities of monolayer material entering and leaving the fold are recorded as well. Maximum material velocities and fold depths are found to be on the order of 0.1 mm/s and 1 mm, respectively. Analysis also reveals that the unfolded material displacement follows a characteristic curve. Mechanical properties of the monolayer are also probed with optical tweezer microrheology.

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Authors

  • Thomas Boatwright

    Department of Physics and Astronomy, University of California, Irvine

  • Jeffrey Yu-Chieh Yang

    Department of Physics and Astronomy, University of California, Irvine

  • Alex Levine

    University of California, Los Angeles, UCLA, Department of Chemistry and Biochemistry, UCLA, Department of Chemistry and Biochemistry, University of California, Los Angeles, Department of Chemistry \& Biochemistry and The California Nanosystems Institute, UCLA, Los Angeles, CA, USA

  • Michael Dennin

    Department of Physics and Astronomy, University of California, Irvine