Facile preparation of high-temperature-resistant ionic liquid@porous hollow glass microcapsules for self-lubricating PA6 composites

Abstract

A novel type of ionic liquid-loaded microcapsules with high loading capacity and high temperature resistance were fabricated by a facile environmentally friendly microencapsulation. Porous hollow glass bubbles were prepared by a subcritical water treatment method and used as microcontainers. The formation process of porous structure and the relationship between the morphology of the porous hollow glass bubbles and the subcritical treatment conditions were studied in detail. 1-propyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl) imide ionic liquid (PMImNTf2 IL) was selected as a lubricant, and IL@porous hollow glass bubbles microcapsules were prepared by simple physical impregnation. The average diameter and wall thickness of microcapsules were 20 µm and 0.6 µm, respectively, and the loading capacity of IL therein was 68.4 wt%. The prepared IL@porous hollow glass microcapsules shown high temperature resistance, with an initial thermal decomposition temperature of 340 ℃. The tribological properties of self-lubricating PA6 composites with different contents of the microcapsules were evaluated under different friction temperature. At room temperature, the friction coefficient and wear rate of the PA6 composites containing 15 wt% microcapsules were reduced by 73.3 % and 92.8 %, respectively, and the excellent friction resistance was maintained below 100 ℃. The macro and micro morphologies of wear surfaces were observed and analyzed to reveal the self-lubricating mechanism of PA6 composites.