Eur. Phys. J. B 3, 353-358 (1998)
https://doi.org/10.1007/s100510050322

Scattering from solutions of star polymers

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

Corresponding author: ^a marques@phoenix.princeton.edu

Received: 3 September 1997
Revised: 13 January 1988
Accepted: 31 March 1998
Published online: 15 June 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, ) from where the radius of the star can be extracted; the intermediate region () that carries the signature of the form factor of a star with f arms: ; and a high wavevector zone () where the local swollen structure of the polymers gives rise to the usual 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 originating from the sea of blobs.