Polyelectrolyte dynamics electrophoretic mobility

Although the theory of polyelectrolyte dynamics reviewed here provides approximate crossover formulas for the experimentally measured diffusion coefficients, electrophoretic mobility, and viscosity, the validity of the formulas remains to be established. In spite of the success of one unifying conceptual framework to provide valid asymptotic results, in qualitative agreement with experimental facts, it is desirable to establish quantitative validity. This requires (a) gathering of experimental data on well-characterized polyelectrolyte solutions and (b) obtaining the relationships between the various transport coefficients. Such data are not currently available, and experiments of this type are out of fashion. In addition to these experimental challenges, there are many theoretical issues that need further elaboration. A few of these are the following ... 

Here Vp has been replaced with the pressure difference between the two points is AP, K°, and K are, respectively, the usual conductivity and the complex conductivity of the electrolyte solution in the absence of the particles, (f> is the particle volume fraction, (j)c is the volume fraction of the particle core, Vc is the volume of the particle core, volume fraction of the polyelectrolyte segments, I4 is the total volume of the polyelectrolyte segments coating one particle, and po, are respectively, the mass density of the particle core and that of the electrolyte solution, and ps is the mass density of the polyelectrolyte segment, V is the suspension volume, and p(cai) is the dynamic electrophoretic mobility of the particles. Equation (26.4) is an Onsager relation between CVP and pirn), which takes a similar form for an Onsager relation between sedimentation potential and static electrophoretic mobility (Chapter 24). 

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 ... 

This chapter deals with the layer-by-layer (LbL) assembly of polyelectrolyte multilayers of polypeptides (poly L-ly sine/poly L-glutamic acid) and polysaccharides (chitosan/dextran suliate) onto soft and porous thermo-responsive poly (N-isopropylacrylamide-co-methacrylic acid) (P(NiPAM-co-MAA)) nanogels. The formation of the LbL structures and characterization of hydro-dynamic radius, electrophoretic mobility, bilayer thickness and stability over time of the systems will be comparatively discussed. Further, the assembly of biopolymers onto similar microgels will be analyzed. The results presented demonstrate that the structure and properties of biocompatible multilayer films can be finely tuned by confinement onto soft and porous gels, which provides new perspectives for biomedical plications, particularly storage and controlled release of biomolecules. 

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