Electrophoretic mobility reversal of polyampholytes induced by strong electric fields or confinement

We investigate the mobility of polyampholytes consisting of both negatively and positively charged sections. The simulations are carried out using molecular dynamics simulations with electrohydrodynamical effects taken into account via a simple coupling scheme to a lattice-Boltzmann fluid. Our results show a previously predicted mobility reversal of the polyampholytes as the applied electric field is increased due to stretching of the polyampholytes. Further, we show that a similar mobility reversal can be induced due to confinement between parallel plates. At high electric field strengths, the polyampholytes' electrophoretic mobility is a non-monotonic function of the distance between the plates. These results help to clarify the role of deformation and confinement on the electrophoretic mobility of polyampholytes.