Production, characterization, and solution properties of dextran fractions of narrow molecular weight distributions

Fractional solution, fractional precipitation, and fractionation by incompatibility with polyethylene glycol are described for the preparation of dextran fractions in the molecular weight (MW) range from 10,000 to 500,000. Polydispersity (Mw/Mn) was about 1.1 at low MWs, increasing up to 1.3 for high MWs. Dextran fractions of lower polydispersity ( 2000 are almost perfect statistical coils in solution and that interactions between dextran molecules in solution are small, so that no association occurs. For MWs < 2000 solution properties give support to the assumption that transition to rodlike conformation occurs.