Synergistic Strengthening and Toughening of Epoxy Composites via Li + ‐π Interaction Induced Microsphere Rolling Mechanism: Rotational Stability and Wide‐Range Effect

Abstract The intrinsic trade‐off between strength and toughness in epoxy resins significantly constrains the engineering applications. To address this challenge, modified spherical silica nanofillers are incorporated into epoxy resins to induce “rolling behavior” driven by triple interfacial Li + ‐π interactions in this study. Interfacial Li + ‐π interactions, characterized by high binding energy and rotational stabilization, can continuously generate the driving force required to induce long‐range rolling of microsphere fillers. As a result, the composite epoxy resin achieves an elongation at break of 18.48%, a tensile strength of 95.32 MPa, and a static toughness of 12.01 MJ m −3 , representing enhancements of 57.24% in strength and 636.81% in toughness, compared to the original epoxy substrate. The microsphere rolling mechanism, activated by mechanical or thermal stimulation, significantly enhances the strength and toughness of epoxy resins. Moreover, its pronounced “thermos‐force equivalence” offers a conceptual framework for the development of robust room‐temperature mechanically triggered self‐healing thermosets.