Theory of electrophoretic mobility of a polyelectrolyte in semidilute solutions of neutral polymers

An explicit formula is derived for the electrophoretic mobility of a polyelectrolyte molecule in a semidilute solution of neutral polymers in terms of the molecular weight N of a polyelectrolyte, concentration c of neutral polymers, Debye length and solvent quality. The nature of the crossover between different regimes, as c, N , and the salt concentration are varied, is presented. The calculations show that one progressively enters into regimes of no‐separation, separation, and no‐separation in the electrophoresis of polyelectrolytes as c is increased. If c is very high, one returns to the mechanism of separation in gel electrophoresis.