Electric-field frictional effects in confined zwitterionic molecules

We theoretically explore the effect of a transverse electric field on the frictional response of a bi-layer of packed zwitterionic molecules. The dipole-moment reorientation promoted by the electric field can lead to either stick-slip or smooth sliding dynamics, with average shear stress values varying over a wide range. A structure-property relation is revealed by investigating the array of molecules and their mutual orientation and interlocking. Moreover, the thermal friction enhancement previously observed in these molecules is shown to be suppressed by the electric field, recovering the expected thermolubricity at large-enough fields. The same holds for other basic tribological quantities, such as the external load, which can influence friction in opposite ways depending on the strength of the applied electric field. Our findings open a route for the reversible control of friction forces via electric polarization of the sliding surface.

Automated summary

This article theoretically explores the effect of a transverse electric field on the frictional response of a bi-layer of packed zwitterionic molecules. The reorientation of dipole moments caused by the electric field can result in either stick-slip or smooth sliding dynamics, with average shear stress values varying widely. The study reveals a structure-property relationship by investigating the arrangement and mutual orientation of the molecules. Additionally, the electric field suppresses the thermal friction enhancement previously observed in these molecules, restoring the expected thermolubricity at sufficiently large fields. Other basic tribological quantities, such as external load, also exhibit opposite influences on friction depending on the strength of the applied electric field.