On the pearl size of hydrophobic polyelectrolytes

¹ Laboratoire des Fluides Organisés, CNRS UMR 7125, Collège de France 11 place Marcelin Berthelot, 75005 Paris, France
² Department of Physics, University of Surrey - Guildford, Surrey GU2 7XH, UK

Corresponding author: claudine.williams@college-de-france.fr

Received: 9 December 2002
Accepted: 22 January 2003

Abstract

Hydrophobic polyelectrolytes have been predicted to adopt a unique pearl-necklace conformation in aqueous solvents. We present in this letter an attempt to characterise quantitatively this conformation with a focus on , the pearl size. For this purpose polystyrenesulfonate (PSS) of various effective charge fractions and chain lengths N has been adsorbed onto oppositely charged surfaces immersed in water in condition where the bulk structure is expected to persist in the adsorbed state. In situ ellipsometry has provided an apparent thickness of the PSS layer. In the presence of added salts, we have found (a is the monomer size) in agreement with the scaling predictions for in the pearl-necklace model if one interprets as a measure of the pearl size. At the lowest charge fractions we have found for the shorter chains, in agreement with a necklace/globule transition.