Polyelectrolytes. III. Viscosities of n‐butyl bromide addition compounds of 4‐vinylpyridine‐styrene copolymers in nitromethane‐dioxane mixtures

Abstract

A series of copolymers, of 4‐vinylpyridine and styrene, covering the range 1.5 to 100% vinylpyridine were prepared in 20% toluene solution at 80°. Strong electrolytes were then made by the addition of n‐butyl bromide in nitromethane solution. The salts with high vinylpyridine content were soluble in water, alcohols, nitromethane, and other polar solvents. Viscosities of the parent copolymers in methyl ethyl ketone were in the range 0.15–0.20; osmotic pressures gave molecular weights in the range 50,000‐80,000. The polyelectrolytes in nitromethane and nitromethane‐dioxane mixtures gave viscosity‐concentration curves which were strongly concave upwards: at 1 mg./100 cc., the reduced viscosity of the salt of polyvinylpyridine in nitromethane was 6.0. The salts of the different copolymers did not differ much in their viscosities at concentrations above a few tenths of a gram per 100 cc., a fact which shows a high degree of ionic association; only as zero concentration is approached, can the detailed polymer structure be seen. The extent of association at a given concentration is controlled by the amount of vinylpyridine in the copolymer and by the dielectric constant of the solvent. Addition of simple one‐one electrolytes, such as tetrabuty lammonium bromide, suppresses the electrostatic increase in viscosity which otherwise appears at low concentrations. The following empirical equation: was found to fit the data for the different systems studied. The constant A depends on copolymerization ratio and probably on molecular weight; it is a measure of the extent to which the polymer coil can spread out at infinite dilution as a consequence of the intramolecular Coulomb repulsion between charges attached to the chain. It is roughly several orders of magnitude larger than the intrinsic viscosity of the parent polymer. The constant B is a measure of the electrostatic forces and increases with decreasing dielectric constant of the solvent.

Conformational Role of Xanthan Gum in its Interaction with Guar Gum

“…The Huggins equation was followed for all samples when the concentration was below the C* (0.075 g/dL for deacetylated xanthan). The characteristic of flexible polyelectrolytes was not noted in any systems in this study, whereas in native xanthan/guar/water systems, when xanthan was the main component in the mixture, instead of following the Huggins equation, the reduced viscosity underwent a marked increase with dilution and approached infinity at zero concentration, a characteristic of flexible polyelectrolytes according to the Fuoss empirical equation (Fuoss and Strauss 1948;Fuoss and Cathers 1949). A possible explanation is that the chain of the deacetylated xanthan was not flexible enough to exhibit the property of flexible chain polyelectrolytes under the experimental condition where the ionic strength of solvent from sodium azide was still higher than that of the xanthan chain (Wang 2001).…”

Electron Microscopy of Dna Molecules "Stained" With Heavy Metal Salts

“…The copolymer of styrene and vinyl pyridine was synthesized as described in the literature (6,9). Films cast on glass slides from a 1 per cent solution in chloroform, as suggested by Birbeck and Stacey (6), were difficult to float off and not of uniform thickness.…”

Phosphorylated polysaccharides. 3. Synthesis of phosphorylated curdlan and its polyelectrolyte behaviour compared with other phosphorylated polysaccharides

“…where A is the intrinsic viscosity and B is a constant (Dragan, Mihai, & Ghimici, 2003;Fuoss & Cathers, 1949;Strauss & Smith, 1953;Wolf, 2007;Ydens, Moins, Degee, & Dubois, 2005). In Fig.…”