In this simulation, we have considered a PMETAC chain that is of the same size (number of monomers) as the PMETAC brushes considered in this study. Therefore, we can infer that the antielectrophoretic response of the PMETAC brushes is due to a combination of its interaction with the Cl -counterions and the fact that they are grafted and hence cannot undergo a physical displacement like a free chain. Of course, such counterion screening is true for all brushes. We have studied the response of several other brushes (e.g., Poly-acrylic or PAA brushes, Polystryrene Sulfonate or PSS brushes) to applied axial electric fields (of similar strengths ~V/nm). In none of these previous studies, we have noted such anti-electrophoretic responses of these brushes. For these cases, the counterions (e.g., Na + ions) are very tightly bound to the brushes: consequently, these counterions do not experience a very large velocity in presence of the applied electric field and hence cannot dictate the brush motion. On the other hand, for the present case, the specific chemical architecture of the {N(CH3)3} + group of the PMETAC brushes ensure that the Cl - counterions are loosely bound to the brush layer, although they do not completely leave the brushes. Such very unique set-up ensures that in the presence of the applied electric field the Cl - ions experience a very large velocity, which in conjunction to the fact that these ions never completely leave the brush layer (and thus exert enough electrostatic pull on these brushes) and that the brushes are grafted and hence cannot undergo any physical displacement, enforces the brush layer to follow the counterion motion and demonstrate anti-electrophoretic response.