Ultralow Tribological Properties of Polymer Composites Containing [BMIm]PF₆‐Loaded Multilayer Wall Microcapsule

Multilayer wall microcapsules efficiently loaded with a lubricant (ionic liquid [BMIm]PF 6 ) are successfully synthesized via a combination of interfacial and in situ polymerization reactions based on lignin nanoparticle–stabilized Pickering emulsion templates. The resulting microcapsules are spherical in shape, with an ideal structure of a rough outer surface and a smooth inner surface. The mean diameter and wall thickness of the resultant microcapsules are 52 ± 18 µm and 3–6 µm. The core fraction is ≈71.29 wt%. Compared with the pure epoxy resin, the friction coefficient of self‐lubricating composites decreases by 83.6% (from 0.55 to 0.09) and the wear rate decreases by 218 times (from 76.8 × 10 −14 to 0.352 × 10 −14 m 3 N −1 m −1 ) by incorporating 20 wt% of the resultant microcapsules into the epoxy resin. It is demonstrated that [BMIm]PF 6 , a more efficient lubricant, release from the microcapsules during the friction process produced a boundary lubricating film. The bipolar property of [BMIm]PF 6 makes the lubricating film firmer, which can efficiently prevent direct contact between the resin matrix and counterface. Furthermore, the rough poly(urea‐formaldehyde) outer surface of multilayer microcapsules brings in an improved interface property between the microcapsules and resin matrix.