J. Phys. II France
Volume 7, Numéro 6, June 1997
Page(s) 931 - 946
DOI: 10.1051/jp2:1997163
J. Phys. II France 7 (1997) 931-946

On the Shape and Rheology of Linear Micelles in Dilute Solutions

W. Carl1, R. Makhloufi2, 3 and M. Kröger2, 4

1  Fraunhofer-Institut für angewandte Materialforschung, Kantstr. 55, 14513 Teltow, Germany
2  Laboratoire de Physique des Liquides et Interfaces, Groupe Rhéophysique des Colloïdes, Université de Metz, 57078 Metz, France
3  Department of Chemical Engineering, University of California, Santa Barbara, USA
4  Fritz Haber Research Center for Molecular Dynamics, Hebrew University, 91904 Jerusalem, Israel

(Received 10 March 1996, revised 20 December 1996, accepted 17 February 1997)

We calculate steady state properties of linear (wormlike) micelles modeled as flexible bead-spring chains from both microscopic and mesoscopic models. The latter model is based on an expression for the free energy of Gaussian chains, modified by a term which takes into account a finite scission energy in order to describe micelles, or breakable polymer chains. In equilibrium, the length distribution then depends on two parameters, namely the micellar concentration and the scission energy. Results of this approach are compared both with previous mesoscopic descriptions and Molecular Dynamics (MD) computer simulation results of the FENE-C model of linear micellar solutions (Phys. Rev. E 53 (1995) 2531). The mesoscopic model is extended to describe flow situations. Implications are discussed and compared with NonEquilibrium MD (NEMD) computer simulation results for the length distribution and flow alignment of linear micelles as well as the corresponding rheological behavior. For the case of steady shear flow both models do predict a decrease of the average micellar size with increasing shear rate.

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