Single chain entanglement: A Monte Carlo simulation of dilute solution capillary electrophoresis

The configurational interactions of a single flexible polyelectrolyte probe chain driven at moderate electric field through a single neutral frozen host chain are investigated using the Monte Carlo simulation method. The simulated probe length varies from 25 to 200 Kuhn steps, while the host length remains fixed at 200 Kuhn steps; the probe's charge density and the medium's Debye-Huckel screening length constitute additional parameters. The simulations reveal a strong and chain length dependent entanglement coupling between probe and host, consistent with recent experiments demonstrating that polyelectrolytes can be electrophoretically separated by molecular weight in a dilute solution of neutral polymers. Additionally, charge density and Debye-Huckel screening length are shown to be important factors in the separation mechanism, affecting both the probability of coupling and the duration of resulting entanglements. The scaling exponent relating entanglement time to molecular weight lies between the values of 2 and 3, the respective limits for Rouse and reptation disentanglement dynamics.