Volume 79, Number 6, September 2007
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||28 August 2007|
Single-particle Brownian dynamics for characterizing the rheology of fluid Langmuir monolayers
Institut Curie, Section de Recherche - 26 rue d'Ulm, 75248 Paris cedex 05, France
2 School of Engineering and Applied Sciences, Harvard University - Cambridge, MA 02138, USA
Accepted: 31 July 2007
The Brownian movement of a submicron diameter sphere has been used to study the rheology of Langmuir monolayers of short-chain surfactants in the low-density limit (liquid-expanded phase). We show how the shear viscosity can be derived from previously measured diffusion coefficients (Sickert M. and Rondelez F., Phys. Rev. Lett. 90 (2003) 126104) by using recent theoretical models for a sphere of size much larger than the monolayer thickness. We report the surface viscosity as a function of the occupied surface fraction, which we believe are the first such estimates based on physically consistent experiments and theory. The two models yield values of the surface viscosity 1-510-10 Ns/m and 2-810-10 Ns/m over the entire range of surface densities of the liquid-expanded phase.
PACS: 68.15.+e – Liquid thin films / 66.20.+d – Viscosity of liquids; diffusive momentum transport / 83.85.Jn – Viscosity measurements
© Europhysics Letters Association, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.