Hydrodynamic radii of polyethylene glycols in different solvents determined from viscosity measurements

The hydrodynamic radius, rh, of low molar mass polyethylene glycol, MPEG = (200 to 1000) g·mol-1, in a homologous series of primary alcohols, acetone, and toluene has been determined from viscosity measurements. The viscosity data have been collected using a fast one-point method as well as a more generally used multipoint method. The results for both approaches are in good agreement. For a given average molar mass of PEG, rh is the largest in acetone, methanol, and toluene and shows a decrease with the chain length of the alcohol. For the solvents studied, rh shows an increase with MPEG that can be described adequately by the two-parameter Mark-Houwink equation for MPEG = (400 to 1000) g·mol-1. In the range T = (298.2 to 323.2) K, the influence of the temperature is not significant. © 2008 American Chemical Society