Molecular weight, polyelectrolyte dynamics

Y. Li, J. Xia, and P.L. Dubin Complex Formation Between Polyelectrolyte and Oppositely Charged Mixed Micelles Static and Dynamic Light Scattering. Study of the Effect of Polyelectrolyte Molecular Weight and Concentration. Macromolecules 27, 7049 (1994). 

FIG. 2 Relaxation times of dynamic modes observed in polyelectrolyte solutions and mixtures over a broad range of experimental conditions 0 diffusion of low molecular weight salt diffusion of polyions or polyion segments in semidilute solutions 3 interaction mode in polyelectrolyte mixtures and diffusion of polyelectrolyte domains (clusters). The data are based mostly on the work on linear flexible polyelectrolytes. Relaxation times correspond to scattering at 90°. See text for more details. 

Sedlak M, Amis EJ. Dynamics of moderately concentrated salt-free polyelectrolyte solutions molecular weight dependence. J Chem Phys 1992 96 817-825. 

Forster S, Schmidt M, Antonietti M. Static and dynamic light scattering by aqueous polyelectrolyte solutions effect of molecular weight, charge density and added salt. Polymer 1990 31 781-792. 

Some of the relevant questions primarily motivated by scientific interest are the following. How is the size of a polyelectrolyte affected by molecular weight, intrinsic stiffness, solvent quality, or ionic strength Which observables are well characterized by coarse-grained quantities such as a linear charge density, and which depend on chemical details How are dynamic quantities like viscosity or electrophoretic mobility related to static properties of poly electrolytes ... 

In [93-95] a combination of turbidimetry and static and dynamic light scattering was applied to study the structure of complexes between PDADMAC samples of different molecular weights and charged mixed micelles. A review on such studies of polyelectrolyte-protein complexes is given in [96]. 

Li Y, Xia J, Dubin PL. Complex-formation between polyelectrolyte and oppositely charged mixed micelles—static and dynamic light-scattering study of the effect of polyelectrolyte molecular-weight and concentration. Macromolecules 1994 27 7049-7055. 

The existing theoretical models may be characterized by the number of dynamic components (polyions, co-ions, counterions) being considered explicitly. One-component theories most closely resemble the theories developed for neutral polymer solutions. A rationale for using this approach is that, in the limit of vanishing electrostatic interactions, polyelectrolytes behave as neutral polymers. On the other hand, multi-component theories are based on models developed for low molecular weight electrolytes. This approach is most powerful for strong electrostatic interactions, where polymer effects are less important. 

At higher polymer concentrations with chains interpenetrating, the intrachain hydrodynamic interaction is screened. Under these conditions, the model chain dynamics, called the Rouse model, may be used as far as the molecular weight dependence is concerned, and not for the dependence of the polymer concentration. The Rouse model is inapplicable for describing any dynamical properties of polyelectrolyte chains or uncharged macromolecules in dilute solutions. 

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