Polyelectrolyte charge distribution

The polyelectrolyte chain is often assumed to be a rigid cylinder (at least locally) with a uniform surface charge distribution [33-36], On the basis of this assumption the non-linearized Poisson-Boltzmann (PB) equation can be used to calculate how the electrostatic potential

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One of the main characteristic of polyelectrolyte is the pK of the - COOH function as usually with polyelectrolyte only the intrinsic pK (pKo) extrapolated to zero charge characterizes the polymer [41] one gets 3.30 which is in same range as other carboxylic polymers the apparent values of pK (pKa) depends on the charge distribution, on the polymer concentration, on the ionic strength of the solution and on the nature of the counterions. 

Polydispersity of molecular weights of heparin was recognized in early studies (reviewed in Refs. 9 and 183). However, the polyelectrolyte nature and heterogeneity of charge distribution have hampered accurate determinations of molecular-weight distribution. 

A polyelectrolyte solution contains the salt of a polyion, a polymer comprised of repeating ionized units. In dilute solutions, a substantial fraction of sodium ions are bound to polyacrylate at concentrations where sodium acetate exhibits only dissoci-atedions. Thus counterion binding plays a central role in polyelectrolyte solutions [1], Close approach of counterions to polyions results in mutual perturbation of the hydration layers and the description of the electrical potential around polyions is different to both the Debye-Huckel treatment for soluble ions and the Gouy-Chapman model for a surface charge distribution, with Manning condensation of ions around the polyelectrolyte. 

This review demonstrated that research on diallyldimethylammoium chloride and its polymers have contributed to the general understanding of the polymerization of ionic monomers, the development of methods for the molecular characterization possibilities of cationic polyelectrolytes, and the understanding regarding polyelectrolyte behavior. However, in comparison to the industrial importance of diallyldimethylammonium chloride polymers, the level of fundamental knowledge is far from adequate. In particular, copolymerization processes with monomers other than acrylamide, the characterization of copolymers related to their chain architecture and charge distribution, the dependence of... 

Non-ionic polymer gel, swollen with dielectric solvent, can be extremely deformed as is the case for non-ionic polymer plasticised with non-ionic plasticiser. Instead of the charge-injected solvent drag as a mechanism of the gel actuation, the principle is based on local asymmetrical charge distribution at the surface of the gel18. The mechanism can also be applied to non-ionic elastomers in which the motion of the polymer chain is relatively free. In spite of their many difficulties for practical actuators, polyelectrolyte gels and related materials are the most interesting electroactive polymer materials. 

These macromolecular compounds when dissolved in a suitable polar solvent (generally water) instantly acquire or can be made to acquire large number of elementary electrical charges distributed along the macromolecular chain. In the former case and when the charge that appears spontaneously has its maximum value, these macromolecules are termed low molar-mass (LMM) electrolytes and in other cases weak polyelectrolytes. 

The intrinsic electrophoretic mobility of polyelectrolytes is directly linked to the charge-to-surface ratio of the solvated molecule. Therefore CZE can quickly deliver valuable results on charge distribution. By using many chemically different types of polyelectrolytes, the influence of polyelectrolyte structure and of the type, pH, ionic strength and temperature of the background electrolyte can be investigated systematically. 

Solution dH Several investigators (2, 12, 13) have indicated that the solution pH is an important determinant in the precipitation efficiency, and the optimum pH level will vary with both the protein (12) and the polyelectrolyte (5). However, the optimum pH for precipitation of protein by CMC did not change with the degree of substitution (DOS) of the CMC (12). This dependence is expected for the formation of an electrostatic complex. Changes in pH will affect the charge on the polyelectrolyte and the charge distribution on the protein. 

Kokufuta E, Wang B, Yoshida R, Khokhlov AR, Hirata M. Volume phase transition of polyelectrolyte gels with different charge distributions. Macromolecules 1988 31 6878-6884. 

The polyelectrolyte acrylamide copolymers poly(acrylamide-cosodium acrylate), poly(acrylamide-co-acrylic acid), and hydrolyzed polyacrylamide were used to study the effect of charge density and charge distribution. The non-polyelectrolyte acrylamide copolymers N,N-dimethylacrylamide and N,N-diethylacrylamide, were prepared to study the effect of N-substituted monomers. 

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