Nonstoichiometric polyelectrolyte complexes: A mathematical model and some experimental results

Abstract

A mathematical model is presented to describe nonstoichiometric water‐soluble polyelectrolyte complexes, and the predictions are compared with some experimental results. The theory is a mixture of Madelung's theory for ionic crystals and Manning's counterion condensation theory. The central parameters are the degree of complexation, φ, and the degree of counterion binding, θ. All other quantities are known in principle. It is found that there is a competition between complexation and counterion binding. When φ is large, θ is small, or vice versa. The degree of complexation, φ, depends sensibly on the concentration, cs, of the added low molecular salt, the polyanion chain length, N, and the dielectric constant, ϵ, of the solvent. There exists a critical salt concentration, cs,c, at which the complexes salt out and where for cs > cs,c the complexes dissociate back into their single strands, the polyanions, and polycations. Further, φ is larger the smaller the polyanion length and the smaller the solvent dielectric constant are. To prove these predictions we have formed nonstoichiometric complexes between IONENE and PAA and IONENE and PMAA, respectively. The degree of complexation was determined by ultracentrifugation and checked by viscometry. The accord found between theory and experiment is both qualitatively as well quantitatively quite well. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 335–348, 1999

Structure and Physico-Mechanical Properties of Polyelectrolyte Complexes Based on Sodium Carboxymethylcellulose Polysaccharide and Polyacrylamide

“…The possibility of independent variation of formation conditions, the ratio of reagents, and their molecular structure is essentially the basis for controlling the process of formation and production of IPC with a given set of properties [12][13][14][15][16].…”

Influence of Nonstoichiometry on the Viscoelastic Properties of a Polyelectrolyte Complex

“…While preparing PECs simply by mixing polyelectrolyte, usually in aqueous solutions, is straightforward, the resulting material may not be a stoichiometric mixture with equal numbers of Pol + and Pol – . − If the PEC composition is nonstoichiometric, additional counterions are required to balance the leftover polymer charge, as shown in Scheme .…”

Complex coacervate core micelles

“…The focus lies on experimental work. See references [21][22][23][24][25][26] for theoretical and modelling papers. Recent developments in selected applications and micelles with heterogeneous coronas are emphasized.…”