A study of dextran hydration in dilute,aqueous solution by the proton magnetic relaxation method

The times of proton magnetic relaxation in dilute (<1%), aqueous solutions of dextrans, having a molecular weight range of 17 x 10³?500 x 10³, are highly sensitive to the temperature—time prehistory of the samples investigated. Reliable results have been obtained only after preliminary heating of the solutions at 100° for 30 min. On the basis of the model of “two states of water in a solution”, the dependence of the degree of hydration of a dextran on its molecular weight has been obtained. In the molecular weight range 17 x 10³?110 x 10³, only a fraction of the D-glucose residues are hydrated, the degree of hydration increasing with the molecular weight. The data obtained are considered to be a consequence of intersegmentary interaction in a dextran macromolecule.