Viscometric Investigation of Chain Conformation and Crosslinking of Dextran in Dilue Aqueous Solutions

Dextran chain conformation and its crosslinking reaction kinetics in dilute aqueous solutions was investigaed as a function of the solution alkalinity. To this end, aqueous solutions of dextran were prepared in the presence of different concentrations of sodium hydroxide. According to the results, the intrinsic viscosity and hydrodynamic coil radius were increased and overlap concentration decreased with increasing in dextran solution pH. Data were interpreted considering the effects of increasing in the solution pH on a corresponding increment in quality of solvent for dextran chains. Finally, the effects of adding a crosslinking agent i.e., epichlorohydrin on the relative viscosity of dextran solutions was investigated. As the solutions were under their critical overlap concentration, viscosity decrement was attributed to the formation of intramolecular crosslinking and the resulting microgels.