Poly counterion distribution

Colloidal sulfide, selenide, telluride, phosphide, and arsenide semiconductor particles are prepared by the controlled precipitation of appropriate aqueous metal ions by H2S, H2Se, H2Te, PH3, and AsH3, respectively. Colloids are stabilized, typically, by sodium poly-phosphate. A large number of experimental parameters determine the size, size distribution, morphology, and chemical composition of a semiconductor particles in a given preparation. Concentrations, rates, and the order of addition of the reagents the counterions selected ... 

H. Gordon and S. Goldman,/. Pbys. Cbem., 96,1921 (1992). Simulations on the Counterion and Solvent Distribution Functions Around Two Simple Models of a Poly electrolyte. 

In this section, we discuss a recent advance in the cell model of poly electrolytes. In the cell model, a cylindrically shaped polyion with all its counterions reside in a cell. The cell is assumed to be cylindrical. The total charge in each cell is zero. Within the framework of cell model, thermodynamic quantities including counterion and co-ion distributions have been studied and compared with the counterion condensation model [45, 46]. 

Consider a dilute suspension of polyelectrolyte-coated spherical colloidal particles (soft particles) in a salt-free medium containing counterions only. We assume that the particle core of radius a (which is uncharged) is coated with an ion-penetrable layer of polyelectrolytes of thickness d. The polyelectrolyte-coated particle has thus an inner radius a and an outer radius b = a + d (Fig. 6.4). We also assume that ionized groups of valence Z are distributed at a uniform density N in the poly electrolyte... 

Rivas BL, Moreno-Villoslada I. Evaluation of the counterion condensation theory from the metal ion distributions obtained by ultrafiltration of the system poly(sodium 4-styrenesulfonate)/Cd2+/Na+. J Phys Chem B 1998 102 11024-11028. 

Carlo studies of counterion DNA interactions - comparison of the radial-distribution of counterions with predictions of other poly-electrolyte theories. J Phys Chem 89 3984-3994. doi 10.1021/... 

With isotopic labelling experiments, not only the polyion-polyion structure factor, but also other partial structure factors such as counterion-counterion structure factors, have been determined [137, 138]. First experiments provide evidence that the counterion-counterion structure factor also exhibits a peak at nearly the same position as the peak in the polyion-polyion structure factor. This is interpreted to originate from condensation of counterions onto the polyions. A similar observation was also made using SAXS by studying poly-potassiumstyrenesulphonate (KPSS) and NaPSS [139], where the scattering curve is mostly determined by the distribution of counterions because of their high contrast factor. 

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