POLYELECTROLYTE ADSORPTION FROM SALINE SOLUTIONS
1983; Elsevier BV; Linguagem: Inglês
10.1016/b978-0-12-530980-6.50023-1
AutoresJohan Marra, H.A. van der Schee, G. J. Fleer, J. Lyklema,
Tópico(s)Nanopore and Nanochannel Transport Studies
ResumoThis chapter presents an overview of the study of the adsorption of polyelectrolytes from saline solutions. In the method described in the chapter, the intrinsic viscosity of polystyrene sulfonate samples in saline solutions was measured in a Viscometer, equipped with a capillary that had a flow time of ca. 230 s for water. For uncharged polymers, it is possible to define a polymer–solvent interaction parameter from the molecular weight dependency of using a Flory–Fox–Schaefgen or a Burchard–Stockmayer–Fixman plot. For lower potentials or at higher cs, the screening by the salt suppresses the minimum and increases the adsorbed amount, while the profile becomes gradually similar to that of uncharged polymer. Purely electrostatic effects greatly influence the adsorption at very high salt concentration. This is related to the interpenetration of small ions between the individual polyion charges, which is not analogous to the two-dimensional screening effect of salt between two impenetrable colloid particle surfaces. One of the most salient features of this polyelectrolyte adsorption is that the effect of electrolytes can be well represented by the Poisson–Boltzmann picture up to concentrations of order 1-3 M, which is far beyond the usually accepted limit of applicability.
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