Polyelectrolyte theoretical consideration

According to theoretical considerations, fa increases if the charge distance on the polyelectrolyte chain becomes larger. This could be shown for DADMAC/AAM copolymers for charge distances in the range of 0.5 to 1.9 nm (Table 10). For b < 1B the fa values are within the limits of the Manning theory and below the values calculated by Gueron. However, for b > 1B the experimental values are remarkably below the theoretical values (Table 10). 

Studies on the interaction between oppositely charged polyelectrolytes date back to 1896 when Kossel389 precipitated egg albumin with protamine. Since that time extensive studies have been made on pairs of strong polyelectrolytes, pairs of strong and weak polyelectrolytes, pairs of weak polyelectrolytes, as well as on amphoteric complexes. However, the theoretical considerations of intermacromolecular interactions between polyelectrolytes were only based on extremely simplified model systems. However, even in the case of such systems, there are many unsolved problems such as the determination of the local dielectric constant in domains of macromolecular chains, the evaluation of other secondary binding forces, especially hydrophobic interactions, and so on. 

Theoretical considerations of the coulombic interactions of dissolved biopolymers have produced a complete picture of the distributions of counter and coions under the influence of the electrostatic charge on the macroion(56,57). The counterion condensation theory of Manning(56) has stimulated a great deal of activity in the study of dissolved macroions, especially because it provides a group of limiting laws describing the contribution of electrostatic effects to the thermodynamic and transport properties of polyelectrolyte solutions. Data... 

In the following paper, the possibility of equilibration of the primarily adsorbed portions of polymer was analyzed [20]. The surface coupling constant (k0) was introduced to characterize the polymer-surface interaction. The constant k0 includes an electrostatic interaction term, thus being k0 > 1 for polyelectrolytes and k0 1 for neutral polymers. It was found that, theoretically, the adsorption characteristics do not depend on the equilibration processes for k0 > 1. In contrast, for neutral polymers (k0 < 1), the difference between the equilibrium and non-equilibrium modes could be considerable. As more polymer is adsorbed, excluded-volume effects will swell out the loops of the adsorbate, so that the mutual reorientation of the polymer chains occurs. 

This chapter is devoted to a miscellaneous group of aqueous acid-base cements that do not fit into other categories. There are numerous cements in this group. Although many are of little practical interest, some are of theoretical interest, while others have considerable potential as sustained-release devices and biomedical materials. Deserving of special mention as biomedical materials of the future are the recently invented polyelectrolyte cements based on poly(vinylphosphonic adds), which are related both to the orthophosphoric acid and poly(alkenoic add) cements. 

If we take into consideration that the lowest experimentally possible polyelectrolyte concentration cp is approximately 10 6 monomol L 1, it follows from Table 8 that the diluted solution state, cp 2000, i.e. if Mn >320,000 g-mol The theoretical treatment and the experimental studies of the concentration dependent behavior of polyelectrolytes in solution is usually restricted to the case with or without an excess of a low molecular electrolyte. A relatively limited amount of data exist for similar concentrations of polyelectrolytes and low molecular mass salt [97]. 

Polyelectrolyte brushes are macromolecular monolayers where the chains are attached by one end on the surface and, at the same time, the chains carry a considerable amount of charged groups. Such poly electrolyte structures have received thorough theoretical treatment, and experimental interest has been vast due to the potential of brushes for stabilising colloidal particle dispersions or for... 

To end, we must emphasize that methacrylates in medicine are made use of in diverse areas including bone and dental cements (109), and as surface modifiers to prevent or delay process of rejection (110), and that each commands a formidable literature. The reader should also be aware of the considerable effort which has been directed towards a phenomenological and theoretical understanding of the solution and swelling properties of synthetic hydrogel and polyelectrolyte polymers (111-116). 

In the above calculation, the volume fraction is estimated without the counter ion layer. If we include the counter ion layer (with the Debye-Hiickel radius approximately 200 A. at the ionic strength used for measurements), the volume fraction will be larger than that used above by a factor of 15 to 20. Therefore, the volume fraction of the solution used for the measurement is 6.0 instead of 0.375%. Thus the observed specific dielectric increment would be 2.5 X 104, which is still considerably larger than the theoretical value. As we have seen, there are great uncertainties concerning the estimation of the volume fraction of polyelectrolytes. Under these conditions, it may be better to discuss the problem on a qualitative basis and not take the numerical agreement as conclusive. 

Regulation of the physico-chemical properties of colloid dispersions by polyelectrolytes is of great interest from the theoretical and practical points of view [89]. A consideration of the peculiarities of absorption of polyelectrolytes on disperse particles can be of help to clarify some aspects of kinetics and mechanism of flocculation, elemental acts of flocculation, as well as to provide the se-... 

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