Tunable tribological properties in water-based lubrication of water-soluble fullerene derivatives via varying terminal groups

In this paper,three kinds of water-soluble fullerene derivatives were synthesized via electrophilic addition reaction and cycloaddition reaction,respectively.The chemical composition characterizations of these derivatives indicated the successful preparation of C60(OH)x,C60(C(COOH)2)x and C60(OH)x(NHCH2COOH)y fullerene derivatives.The aggregation and morphology characterizations showed that the three kinds of derivatives had an ideal spherical aggregating structures and excellent dispersibility in water,especially C60(OH)x and C60(C(COOH)2) x.The lubrication performance of the fullerene derivatives acted as lubricant additives were investigated at different concentrations in the range of 0-1 wt%.The results indicated that the addition of polyhydroxyl and carboxylic derivatives could improve the lubrication properties,which led to the reduction of wear to about 40% at most.It is attributed that the optimized substitutions of fullerene molecules may be of benefit to their distribution properties and lubricating behaviors in water based lubrication.