High‐Performance Self‐Lubricating Epoxy Composites Using Bioinspired Silica Microcapsules: Interfacial Engineering and Tribological Performance

ABSTRACT This study introduces high‐performance self‐lubricating epoxy composites incorporating bioinspired silica microcapsules. Fabricated via optimized oil‐in‐water emulsion, the microcapsules (8–22 μm diameter, 0.5–0.6 μm shell thickness) demonstrate excellent thermal stability (200°C for 1 h) and high polyalphaolefin (PAO) encapsulation efficiency. At 5.0 wt% loading, the composite achieves outstanding tribological performance with an 89% reduction in both friction coefficient (from 0.56 to 0.08) and wear rate (from 120 to 13 × 10 −6 mm 3 /Nm) under 5 N load, while retaining 85% of compressive strength. Microstructural analysis confirms uniform microcapsule dispersion and strong interfacial adhesion with the epoxy matrix. The composite exhibits a unique stress‐responsive lubrication mechanism where mechanical triggers cause microcapsule rupture, releasing PAO to form continuous lubricating films combined with silica fragments. This dynamic process is quantitatively described by a conceptual kinetic framework model that accounts for stress‐dependent rupture and lubricant entrainment. The excellent balance of tribological properties and mechanical integrity demonstrated under laboratory conditions makes these composites promising candidates for further investigation toward demanding applications.