Springer LINK: The European Physical Journal B - Abstract Volume 3 Issue 3 (1998) pp 353-358

The European Physical Journal B

ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)

Table of Contents

Abstract Volume 3 Issue 3 (1998) pp 353-358

Scattering from solutions of star polymers

C.M. Marques (1) (a), D. Izzo (2), T. Charitat (3), E. Mendes (4)

(1) CNRS - Rhodia, Complex Fluids Laboratory, Cranbury, NJ 08512-7500, USA
(2) Instituto de Física da Universidade Federal do Rio de Janeiro, 21945-970 Rio de Janeiro, Brazil
(3) Université Joseph Fourier, LPNSC, CNRS, 25 avenue des Martyrs, B.P. 166, 38042 Grenoble Cedex 09, France
(4) Laboratoire d'Ultrasons et de Dynamique des Fluides Complexes, 4 rue Blaise Pascal, 67070 Strasbourg, France

Received: 3 September 1997 / Revised: 13 January 1988 / Accepted: 31 March 1998

Abstract: We study the scattering intensity of dilute and semi-dilute solutions of star polymers. The star conformation is described by a model introduced by Daoud and Cotton. In this model, a single star is regarded as a spherical region of a semi-dilute polymer solution with a local, position dependent screening length. For high enough concentrations, the outer sections of the arms overlap and build a semi-dilute solution (a sea of blobs) where the inner parts of the actual stars are embedded. The scattering function is evaluated following a method introduced by Auvray and de Gennes. In the dilute regime there are three regions in the scattering function: the Guinier region (low wave vectors, $q R \ll 1$) from where the radius of the star can be extracted; the intermediate region ($1 \ll q R \ll f^{2/5}$) that carries the signature of the form factor of a star with f arms: $I(q) \sim q^{-10/3}$; and a high wavevector zone ($q R \gg f^{2/5}$) where the local swollen structure of the polymers gives rise to the usual q^-5/3 decay. In the semi-dilute regime the different stars interact strongly, and the scattered intensity acquires two new features: a liquid peak that develops at a reciprocal position corresponding to the star-star distances; and a new large wavevector contribution of the form q^-5/3 originating from the sea of blobs.

PACS. 87.22.Bt Membrane and subcellular physics and structure - 82.70.Dd Colloids

(a) email: marques@phoenix.princeton.edu

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