Size-based separation of synthetic polyelectrolytes in entangled polymer solution capillary electrophoresis: the effect of binary mixtures of separating polymers differing in molecular mass

The influence on the electrophoretic behavior of polystyrenesulfonates of the percentage of high-molecular-mass chains in an entangled poly(ethylene oxide) solution having a bimodal molecular mass distribution has been investigated and compared with the results obtained for similar solutions of unimodal molecular mass distribution. The comparisons between the different separating polymer solutions were made at a constant total mass concentration, so as to keep constant the mesh size and to highlight the sole effect of the network dynamics. The use of binary polymer mixtures of two different molecular masses but of same nature can be a convenient alternative to modulate the dynamics of the network and the viscosity of the separating medium. A 20-30% content of high-molecular-mass chains in an entangled poly(ethylene oxide) solution having a binary molecular mass distribution appears to be a good compromise for a moderate viscosity and a good separation selectivity in comparison with a solution containing only chains of high molecular mass at the same concentration.