Persistence length for a model semirigid polyelectrolyte as seen by small angle neutron scattering: a relevant variation of the lower bound with ionic strengthE. Buhler1, 2 and F. Boué3
1 Centre de Recherches sur les Macromolécules Végétales-CNRS, UPR 5301, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
2 Groupe de Dynamique des Phases Condensées, UMR 5581, CC26, Université de Montpellier 2, 34095 Montpellier Cedex 5, France
3 Laboratoire Léon Brillouin (CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette, France
(Received 20 June 2002 and Received in final form 21 January 2003 Published online: 16 April 2003 )
In a SANS experiment, we have directly determined for the first time the conformation of hyaluronan, a model semirigid polyelectrolyte. At high ionic strength, this is completely possible, where the scattered intensity crosses over (when decreasing q) from a q-1 rod variation to a q-2 and, where fitting to the "wormlike" chain model gives the backbone, intrinsic, persistence length: L0=86.5 Å. At low ionic strength, we can safely check that the measured persistence length appears increased by at least the amount predicted by Odijk for the electrostatic contribution, (~ , square of the Debye screening length). However, the intensity at the lowest q is not only due to the single chain, since it crosses over from a q-1 to a q-4 variation, characteristic of polymer associations.
61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling.
82.35.Rs - Polyelectrolytes.
83.85.Hf - X-ray and neutron scattering.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003