Eur. Phys. J. B 12, 253-260 (1999)
https://doi.org/10.1007/s100510051002

Ionic distribution and polymer conformation, near phase separation, in sodium polyacrylate/divalent cations mixtures: small angle X-ray and neutron scattering

¹ Service de Chimie Moléculaire, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
² LURE, Université Paris-Sud, Bâtiment 209 D, 91405 Orsay Cedex, France

Corresponding author: ^a delsant@scm.saclay.cea.fr

Received: 21 January 1999
Published online: 15 November 1999

Abstract

Anomalous small angle X-ray scattering experiments show that before demixion in sodium polyacrylate/cobalt and sodium polyacrylate/calcium mixtures all the divalent counterions are in the close vicinity of the polyacrylate chain. The present results are consistent with previous UV/VIS spectroscopy, which have shown that all cobalt ions are chemically associated with acrylate groups. The chemical association dehydrates the acrylate monomers. However, the hydrophobicity of the complexed monomers is not strong enough to induce a collapse of the polymer chain at small spatial scale before the demixion. Indeed, the scattered intensity (X-ray and neutron scattering) decreases with the scattering vector q as with for which indicates that the local conformation of the chain is Gaussian.