PNNL

Abstract

In this work, methacrylate-type ionic liquid (IL) monomers containing a quaternary ammonium cation and two different counter-anions were synthesized and used as co-monomers to obtain functional poly(alkyl methacrylates) (PAMAs) as friction and wear reducing additives for lubricants. The effect of molecular weight, polymer topology (random or diblock), and IL counter anion on friction and wear behavior of polymer PAO (poly-alpha olefin) solutions have been investigated. The results were compared to those of PAO solutions additized with a small molecule, non-polymeric ionic liquid, or non-ionic copolymers containing 2-(dimethylamino)ethyl methacrylate (DMAEMA) as the polar comonomer. No clear correlation between polymer molecular weight and friction or wear behavior was observed. Random ionic liquid copolymers led to lower wear volumes than their block counterparts. Polymers containing dicyanamide (DCA) counter anion showed lower wear volume compared to those containing bis((trifluoromethyl)sulfonyl)imide (TFSI) anion. Surprisingly, none of the IL copolymers studied outperformed the DMAEMA containing block copolymer in terms of wear volume reduction, suggesting the IL moiety had no beneficial effect on wear.