Dilute solution properties and degree of chain branching for dextran

Hydrodynamic volume, radius of gyration, and viscometric constants, K and a, for dextran, with a wide molecular weight range were calculated using experimental reported average-molecular weights (Mn, Mw), and intrinsic viscosity, [η], data in water and 0.05 M Na2SO4. Degree of chain branching for dextran was also determined using different procedures. This study demonstrated that hydrodynamic volume and radius of gyration of a dextran sample with Mw < 20 kDa and its linear counterpart with equal Mw are almost identical, whereas the latter parameters for a dextran sample with Mw > 20 kDa was smaller than that of its linear counterpart. Values of 0.506 in water and 0.512, 0.425 and 0.273 in 0.05 M Na2SO4 for the exponent a were obtained. A smaller value for a was obtained for a larger Mw range. Molecular weights of desirable nano-particles for various branches of nanotechnology can be estimated from a derived radius of gyration–molecular weight relationship.

► Radius of gyration and viscometric constants for dextrans were calculated.
► Degree of chain branching for dextrans was estimated using four procedures.
► The results can be used for synthesized, fractionated, and depolymerized dextrans.
► The results can be also used to characterize fractionated dextrans as standards.