Publication costs assisted by Centre de Recherches sur les MacromoléculesThe electrophoretic mobility of a synthetic, flexible linear polyelectrolyte (an alternating copolymer of maleic acid and ethyl vinyl ether) dissolved in aqueous solutions of NaBr, under various experimental conditions, was measured by inelastic light scattering. We analyzed the influence of the NaBr concentration, the polyacid concentration, the molecular weight of the poly electrolyte, and the degree of neutralization. The results obtained are in agreement with those of previous studies on the subject, but we emphasize the experimental difficulty of obtaining the low polymer concentrations required by limiting laws. An apparent polyion valence was calculated, assuming a Nernst-Einstein relation between the polyion electrophoretic and self-diffusion mobilities. The values obtained were surprisingly low and are discussed in detail.

SynopsisRelations between relaxation and electrophoretic effects in salt-free polyelectrolyte solutions are studied in terms of nonequilibrium thermodynamics and of binary friction coefficients. The significance and the method of determining these coefficients are explained. Consideration of experimental results and of long-and short-range interactions suggests that the concept of "ion condensation" is needed to provide a consistent description of transport processes for linear flexible polyelectrolytes. Empirical relations previously used are shown to have only limited validity.

Publication costs assisted by Centre de Recherches sur les Macromolecules A phenomenological theory of electrical transport in polyelectrolyte-plus-salt solutions is developed. The treatment is based on linear force-flux relationships by using binary frictional coefficients within the framework of linear nonequilibrium thermodynamics. Correlations between conductances and reduced self-diffusion coefficients of counterions and coions are established without taking recourse to an explicit model, and former theories on the subject are generalized. In particular, it is shown that the "intrinsic conductivity" of a polyelectrolyte in excess-of-salt solutions may be related in a simple way to the electrophoretic mobility of the polyion, the transport parameters of small ions in pure salt solutions, and to the lowering of the self-diffusion coefficient of small ions in the presence of the polyelectrolyte. A comparison with recent experimental results displays semiquantitative agreement.

SynopsisElectrophoretic mobilities are studied in polyelectrolyte-plus-salt solutions, using linear irreversible thermodynamics and the concepts of relaxation and electrophoretic effects discussed in paper I. If ionic interactions are treated within the Debye-Huckel approximation, co-ions contribute significantly to the relaxation field experienced by polyions. Moreover, through self-diffusion and electrophoretic measurements, the effective valence of the polyion becomes an experimentally accessible parameter. It should provide another method to check the concept of ion condensation.

Les processus dissipatifs au sein de solutions polyélectrolytiques constituent un ensemble de phénomènes très riche, tant par sa variété que par le nombre de paramètres d'étude intervenant. Nous limitons notre analyse à deux situations-limites, celles de solutions en absence ou avec excès d'électrolyte ordinaire. Le formalisme utilisé est celui de la thermodynamique des processus irréversibles linéaires et les différents coefficients de transport (diffusion, autodiffusion, sédimentation, conductibilité...) sont exprimés en fonction de coefficients de frottement binaires. La signification de ces coefficients de frottement est analysée en établissant le lien avec les classiques effets de relaxation et électrophorétique, et l'on souligne la profonde interdépendance entre interactions hydrodynamiques et électrostatiques. Nous montrons comment les coefficients de frottement peuvent être calculés à partir de données expérimentales ou à partir de théories liées à des modèles. La discussion des résultats obtenus conduit à des conclusions intéressantes concernant : - le phénomène de condensation ionique, - la signification de l'effet de charge en sédimentation et diffusion, - la validité des relations de Svedberg et de Nernst-Einstein. Enfin, la considération de certains résultats théoriques et expérimentaux suggère que l'aspect dynamique des fluctuations de concentration joue sans doute un rôle important, négligé jusqu'à présent dans de nombreuses approches théoriques