Efficacy of hierarchical pore structure in enhancing the tribological and recyclable smart lubrication performance of porous polyimide

Abstract

Herein, a porous oil-containing material with hierarchical pore structure was successfully prepared through microtexturing large pores on the surface of porous polyimide (PPI) with single-level small pores. Compared to the conventional oil-containing material, the hierarchically porous oil-containing material exhibited high oil-content, and retained excellent mechanical properties and high oil-retention because of the synergistic effects of large pores and small pores. Furthermore, the lubricant stored in the hierarchically porous polyimide could release to the interface under thermal-and-mechano-stimuli, and the released lubricant could be reabsorbed into the hierarchically porous polyimide via the capillary-force offered by the porous channel. Based on the high oil-content and recyclable oil release/reabsorption, the hierarchically porous oil-containing polyimide exhibited excellent lubrication performance (coefficient of friction was 0.057).