ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The finding of Pouyet and Sadron that, at extreme dilutions of thymonucleic acid, the specific viscosity at low shear rates is either unaffected or only slightly affected by salts is confirmed with two samples prepared in different ways. The specific viscosity in these solutions increases considerably above the limiting value at very low concentrations and is then markedly sensitive to the presence of salts even at very small concentrations of the latter. The rapid increase of the specific viscosity with increasing concentration must be due to increasing interaction between the particles, and as these interactions are sensitive to small salt concentrations they must be electrostatic in nature. It is suggested that they arise from the Debye-Hückel forces between the particles and their counter ions. When no added salt is present the counter ions can only complete their ion atmospheres by interacting with two of the polyelectrolyte particles and this will give rise to interactions between the particles, which will be greatly reduced by even small concentrations of added electrolytes. Interactions of this type will vary in strength according to the distances of the interacting charges and may be so weak that the shearing stresses can over come them. This will produce the high shear dependence observed in solutions of this kind. The differences between the behaviour of deoxyribonucleic acid and various synthetic polyelectrolytes which have been studied may arise from the fact that in the former the charges are carried by the “backbone” of the fiber and in the latter on side chains which are capable of rotation.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1954.120120116
Permalink
