Rodlike macroions

STUDIES ON DILUTE SOLUTIONS OF RODLIKE MACROIONS ffl. INTEGRATED INTENSITY AND PHOTON CORRELATION UGHT SCATTERING INVESTIGATION OF ASSOCIATION... 

Solutions of the rodlike macroion were prepared by dissolution in methane sulfonic acid (MSA) of deuterated poly(l,4-phenylene-2,6-benzobisthiazole)(d-PBT), which was supplied by Dr. J. R. Wolfe, SRI International. Solutions were prepared in a glove box with air circulated over drierite. The solvent MSA was distilled under vacuum. The solutions were filtered several times with a teflon millipore filter into the light scattering cells in a glove box filled with dry nitrogen. Cells were sealed with flame under vacuum and then centrifuged for 24 hours before measurements. 

FIGURE 7 Schematic model of the rodlike macroion chains of the polyelectrolyte network. As described in the text, only the macroions parallel to the electric field are considered. (From Ref. 21.)... 

B. Halle,/. Chem. Phys., 102,7238 (1995). Orientation-Dependent Electrical Double-Layer Interactions. I. Rodlike Macroions of Finite Length. 

The intrinsic viscosity (rj) is a characteristic value of a single macromolecule in a given solvent and it is a measure of the hydrodynamic volume occupied by the polymer itself. It depends primarily on the molar mass (Mw), chain rigidity, and solvent quality. For anionic polyelectrolytes the presence of macroions and counterions in aqueous media causes coil expansion by intrachain electrostatic repulsion and extra dissipation of energy, thus explaining why the intrinsic viscosity of a polyelectrolyte can be higher than that of a neutral rodlike macromolecule of equal size. Thus, (rj) usually increases with an increase in the charge density of the macroion. 

In order to simplify the model we present in Figure 8 the DNA in the double helical B form as a rodlike polyion. If the solvent is NaQ, the compensating counterions of negative phosphate sites are Na" and the coions of the electrolyte are Cl . It is possible to show that a correlation exists between the conformation of the macroion and some characteristic parameters of the electrolyte. ... 

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