Pyridinium based dicationic ionic liquids as base lubricants or lubricant additives

•Synthesis of eight new dicationic ionic liquids derived from pyridinium.•N-alkylpyridinium cations linked by polyethylene glycol chains.•Thermal analysis of the pure ionic liquids by DSC and TGA.•The dicationic ILs with [NTf2] anion have shown good properties as neat lubricants.•Decrease in COF with low concentration of [NTf2] DLIs in mixtures with glycerol.

A series of eight new dicationic ionic liquids incorporating polyethylene glycol chains linking two N-alkylpyridinium moieties through rings position 2, were synthesized and investigated for their potential use as lubricants or lubricant additives. Alkylsulfate and bis(trifluoromethanesulfonyl)imide [NTf2] were selected as anions. Dicationic ionic liquids containing [NTf2] anion demonstrated good properties as neat lubricants showing low coefficient of friction and wear comparable with the reference lubricant (glycerol). Even more interesting could be their use as friction modifier additives since an important decrease in the coefficient of friction was achieved with a really low concentration of ionic liquid. The thermal analysis of all ionic liquids by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) is also described.