A new outlet for traditional antioxidants: multifunctional additives based on ionic liquid strategy toward excellent lubrication and oxidation resistance

Multifunctional additives are essential to achieve efficient lubrication in practical service. In this work, three novel ionic liquids (ILs) were designed and synthesized based on the traditional antioxidant molecule (3,5-Di-tert-butyl-4-hydroxyphenylpropionic acid). Not only the improvement of oxidation resistance and thermal stability, the strengthening of friction-reducing (decrease by 40 %), anti-wear properties (decrease by 80 %) and stability is more noteworthy when applied as the functional additive of base oil (PAO6). The electrostatic interaction between IL anions and cations and the balance of Van der Waal's forces is favorable for its unique interfacial self-assembly behavior. This work provides theoretical guidance for the design of multifunctional additives and the innovation of high-performance antioxidant lubricants.