Dielectric Properties of Polyelectrolytes in Solution

MANDEL and F. VAN DER TOUW Gorlaeus Laboratoria, Afdeling Fysische Chemie III, Rijksuniversiteit Leiden, The Netherlands 

In the present paper we shall present a summary of some of these results obtained vv ] th aqueous solutions of the following polyelectrolytes  

2 is of the same order of magnitude regardless of the nature of the macromolecule or its degree of dissociation. Perhaps a slight correlation between 2 and the macro-molecular concentration Cp can be noticed. 

We shall now present a theoretical approach both to the value of and to the mechanism underlying the two dispersion regions. Although the solutions which were investigated were not infinitely diluted with respect to the macromolecular component (C,-10- -5 X 10 eq. 1 ) it will assumed in the theoretical interpretation of the 

We shall use the following model in discussing the dielectric properties of the polyelectrolyte solution. Assume a linear distribution of A identically charged (—e) sites equally spaced and situated symmetrically with respect to the center of mass (origin of the internal coordinate x) at positions 2. .. (The linear distribution of 

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Mandel M, van der Touw F. Dielectric properties of polyelectrolytes in solution. In Seleny E, ed. Charged and Reactive Polymers, Volume I. Polyelectrolytes. Dordrecht Reidel, 1974 285-300. 

The properties of polyelectrolytes in solutions and at charged surfaces depend on the fraction of ionized groups, solvent quality for the polymer, dielectric cmistant of the medium, salt COTicentration, and polymer-substrate interactions [5—7],... 

The electrical properties of polyelectrolyte complexes are more closely related to those of biologically produced solids. The extremely high relative dielectric constants at low frequencies and the dispersion properties of salt-containing polyelectrolyte complexes have not been reported for other synthetic polymers. Neutral polyelectrolyte complexes immersed in dilute salt solution undergo marked changes in alternating current capacitance and resistance upon small variations in the electrolyte concentration. In addition, their frequency-dependence is governed by the nature of the microions. As shown in... 

The purpose of this work is to present a synthesis of the important facts known about DNA when considered as a polyelectrolyte. Amongst the numerous physicochemical properties of this fundamental bio-molecule, its behavior in aqueous salt solution is particulary important since it reflects closely the conditions in vivo. We will center the discussion on the interaction between the polyion and its surrounding ionic atmosphere, leaving apart the dielectric properties of the solution. This latter point has already been largely discussed (see References 1-5). 

These examples show that in certain cases (and under certain conditions) non electrostatic interactions can become a predominant factor controlling the state in solution of polyelectrolyte molecules. A very weak polyelectrolyte with a non hydrophylic chain can allow the illustration of such effects. A great deal of work has been carried out on polyanions but only a relatively limited number of studies is concerned with the properties of polycations. In this paper, we would like to present some properties concerning the polyelectrolytic behavior of aqueous solutions of (non quaternized) isomolecular atactic or isotactic poly-2-vinylpyridine (PVP), which have already been the subject of some of our previous investigations [4]. The experiments were performed on solutions without added salt with a few monovalent or bivalent counter-ions the effect of ionization and concentration on viscosimetric and dielectric properties of PVP was investigated. 

The rotation of large molecules in solution together with their hydration is the basis of many of the properties of solutions containing polyions. One has to ask questions, however, about the decrement of the dielectric constant in the case of linear polyelectrolytes, which include DNA. Substances such as this exhibit dielectric decrements as expected but it is difficult to account for their magnitude in terms of hydration. Thus, there might be a rotation but this cannot be about the long axis because in such a case <5 (Section 2.24) should increase when the molecules are oriented perpendicularly to the electric field and this is not found to be the case. 

Table 8). This permits the interpretation of experimental data by using the electro-optical properties of flexible-chain polymers in terms of a worm-like chain model However, EB in solutions of polyelectrolytes is of a complex nature. The high value of the observed effect is caused by the polarization of the ionic atmosphere surrounding the ionized macromolecule rather than by the dipolar and dielectric structure of the polymer chain. This polarization induced by the electric field depends on the ionic state of the solution and the ionogenic properties of the polymer chain whereas its dependence on the chain structure and conformation is slight. Hence, the information on the optical, dipolar and conformational properties of macromoiecules obtained by using EB data in solutions of flexible-chain polyelectrolytes is usually only qualitative. Studies of the kinetics of the Kerr effect in polyelectrolytes (arried out by pulsed technique) are more useful since in these... 

The properties of ionomer solutions are sensitive to not only the degree of the ionic functionality and the polymer concentration, hut perhaps even to a greater extent, the ability of the solvent to ionize the ion-pairs (64). Thus, non-ionizing solvents, usually those with relatively low dielectric constant, favor association of the ionic groups even in dilute solutions. In contrast, ionomer solutions may exhibit polyelectrolyte behavior in polar solvents due to solvation of the ion-pair that leaves the hound ions unshielded. 

A.S. Michaels and R.G. Miekka, Polycation-polyanion complexes Preparation and properties of poly(vinylbenzyltrimethylammonium) and poly(styrenesulfonate), J. Phys. Chem., 1961, 65, 1765-1773 A.S. Michaels, L. Mir and N.S. Schneider, A conductometric study of polyaction-polyanion reactions in dilute solution, J. Phys. Chem., 1965, 69, 1447-1455 S.J. Reid, J. Th. Overbeek, W. Vieth and S.M. Fleming, Membrane potential differences with the polyelectrolyte complex - poly(vinyltrimethy-lammonium)-poly(styrenesulfonate), J. Colloid Polym. Sci., 1968, 26, 222-229, O. Yano and Y. Wada, Effect of sorbed water on dielectric and mechanical properties nf nnlvinn enmnlex../ Ann Polvm. Sci.. 1980. 25. 1723-1735. 

The simplest polyelectrolyte model of biological relevance is that of a single semiinfinite impenetrable charged plane in equilibrium with a bulk electrolyte solution of known composition. The charged plane also serves as an introduction to the properties of the electric double layer. We simplify the representation of a membrane by assuming that (1) the membrane is impenetrable to ions, (2) the surface charge is uniformly distributed and constant, (3) the electrolyte is modeled as hard-sphere ions of specific size, and (4) the solvent is a structureless continuum described by a uniform dielectric coefficient... 

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