Mechanical‐Bond‐Toughened Epoxy Resins

Epoxy resins, while indispensable for their excellent mechanical strength, face fundamental limitations due to their inherent brittleness. Here we present a novel advancement in epoxy toughening through the strategic incorporation of [2]rotaxane-based mechanical bond as mechanically interlocked cross-linker, whose unique intramolecular motion enables efficient energy dissipation and stress redistribution under external force. As a result, the as-prepared mechanically interlocked epoxy networks (^MINEP) exhibit elongation of 272% and toughness of 37.9 MJ m^-3, both representing an order-of-magnitude improvement over the conventional counterpart while showcasing notable properties compared to other epoxy materials. Further, we capitalize on the adhesive effect and good toughness of ^MINEP to toughen graphene films. Compared to pristine graphene films, the ^MINEP-bonded films show significantly enhanced toughness (30.2 versus 3.4 MJ m^-3), elongation (26.5% versus 9.9%), and maximum strength (237 versus 72.3 MPa). This work not only provides an effective strategy for the development of high-performance epoxy resins, but also exploits their application potential in toughening two-dimensional (2D) materials.