Zwitterionic polymer-functionalized nitrogen-doped MXene nanosheets as aqueous lubricant additive

Herein, the zwitterionic polymer functionalized nitrogen-doped MXene (N-MXene) nanosheets were successfully prepared via carbonization method and in-situ surface modification. The N-MXene nanosheets were prepared from MXene with urea assisted carbonization, and then the zwitterionic polymer polyethylenimine-quaternized derivative (PEIS) can in-situ assemble onto the N-MXene surface with tannic acid (TA) via Michael addition to obtain PEIS functionalized N-MXene nanosheets (PEIS@N-MXene). The as-prepared PEIS@N-MXene exhibit good friction reduction and wear resistance as an aqueous lubricant additive. The average coefficient of friction is reduced to 0.109 from 0.633, and the wear volume was reduced by 42.3% compared to pure water, which are attributed to the synergistic effect of the physical and chemical protective film formed by the additive and the hydration layer formed by PEIS.