New Biased-Reptation Model For Charged Polymers

We study entangled charged polymers in an electric field with a new biased-reptation model. Two microscopic time scales are relevant: the usual tube disengagement time $T_D$, and a new chain stretching time constant ${\tau }_{\mathrm{str}}$. When ${\tau }_{\mathrm{str}}<T_D$, i.e., for long chains and/or high electric fields, the chains are stretched in the field direction. As an example, we discuss DNA gel electrophoresis in terms of these results. Experimental and theoretical investigations are suggested.