Interactions of counterions with dextran sulfate in aqueous solutions |
| |
Authors: | Iwao Satake Masao Fukuda Tomohisa Ohta K
zaburo Nakamura Noboru Fujita Akira Yamauchi Hideo Kimizuka |
| |
Institution: | Iwao Satake,Masao Fukuda,Tomohisa Ohta,Kōzaburo Nakamura,Noboru Fujita,Akira Yamauchi,Hideo Kimizuka |
| |
Abstract: | Counterion activity coefficients in solutions of dextran sulfate with and without added salts were determined potentiometrically by using a cation-exchange membrane and a sodium glass electrode. Dextran sulfate was shown to interact with monovalent cations in the order of preference: K+ > Cs+ > Na+ > Li+, whereas no specificity was found for bivalent cations. On the basis of light-scattering measurements, the expansion of the dextran sulfate polyion in solutions of alkali metal salts was found to fall in the same order as the counterion activity coefficients in salt-free solutions. It was also shown that the dextran sulfate polyion assumes a more extended conformation in magnesium chloride solution than in calcium chloride. These results were substantiated by measurements of solution viscosities. |
| |
Keywords: | |
|
|