1070-4272/05/7806-0971 + 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 6, 2005, pp. 971!974. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005,
Original Russian Text Copyright + 2005 by Alekseeva, Rozhkova, Eliseeva, Prusov.
AND POLYMERIC MATERIALS
Structural and Hydrodynamic Characteristics of Dextrans
in Liquid-Phase Media
O. V. Alekseeva, O. V. Rozhkova, O. V. Eliseeva, and A. N. Prusov
Institute of Chemistry of Solutions, Russian Academy of Sciences, Ivanovo, Russia
Received February 9, 2005
Abstract-Viscous and volume properties of solutions of dextran with various molecular weights in water
and dimethyl sulfoxide were studied.
In recent years, the researchers’ attention has been
attracted by natural polymer systems based on poly-
saccharides, which are not only biologically active
compounds, but also an adequate model of amorphous
regions of cellulose for studying solvation interac-
tions in solution. Of particular interest are bacterial
polymers, dextrans. Owing to their unique physico-
chemical properties, they are widely used in medicine
and pharmacology. The practical use of these polysac-
charides as effective blood substitutes makes a study
of their behavior in dilute solutions a matter of current
interest. Unfortunately, publications devoted to this
issue are scarce .
In the present study, viscous and volume properties
of solutions in water and dimethyl sulfoxide (DMSO)
of dextrans with various molecular weights were sub-
jected to a systematic analysis.
Dextrans of Fluka AG Buchs brand, with molec-
ular weights of 70 0 10
3500 0 10
, served as objects
of study. The dextrans were dried in a vacuum at
330 K for 24 h. Water (twice distilled) and DMSO
purified and dehydrated by the procedure described
in  were used as solvents. The content of water
in the solvent was determined by amperometric ti-
tration by the Fisher method to be +0.002%. Poly-
mer solutions were prepared gravimetrically using
a VLR-200 balance with an accuracy of +5 0 10
The viscosity of polymer solutions with concentra-
tions of 3316 kg
was measured with a capillary Ub-
belohde viscometer at 2933303 K. The root-mean-
square error in viscosity measurements was +0.5%.
The dependences of the reduced viscosity of dilute
solutions of dextrans, h
/c, on the polymer concentra-
tion c were linear for all the systems studied (r = 0.98).
The viscometric Huggins constant was found using
the equation from :
is the Huggins constant, which describes
the interaction of segment of polymer macromolecules
with the solvent, and [h] is the characteristic viscosity.
The solvent was characterized by K
,[h], and av-
erage statistical dimensions of macromolecular coils.
The volume V
of a polymer macromolecule and
the root-mean-square distance (
between the chain
ends of polymer macromolecules were calculated by
the formulas [4, 5]:
[h] = 2.5N
were F is the Flory coefficient, which accounts for
the deviation of the actual volume of the macromol-
ecules from the spherical volume and for the partial
permeability of the coil to the solvent; M, molecular
weight of dextran; 2,5, form factor of a spherical par-
, Avogadro number.
The density of dextran solutions was studied with
a vibrational densitometer. The design of the den-
sitometer and the experimental procedure were de-
scribed in . The error in density measurements was
+2 0 10
, which made it possible to calculate
the volume characteristics of dextran with a sufficient
reliability. The volume parameters were evaluated by
an efficient procedure based on the experimentally
measured solution density as the input value.