Polymer Nanoparticles Enable Self‐Adaptive Soft Interface for Vitrimer Elastomer Nanocomposites

Reconciliation of the elasticity, reinforcement, and recyclability in elastomer nanocomposites (ENCs) remains challenging, primarily due to the energy losses of the friction at polymer‐nanoparticle interfaces and the permanent covalent cross‐linking. Here, a self‐adaptive soft interface strategy is introduced, using modulus‐tuned polymer nanoparticles (PNPs) as reinforcement agents and interfacial chemical cross‐linking sites within a vitrimer elastomer matrix. Such a framework promotes synergistic deformation of the PNPs with the matrix chains during mechanical deformation to minimize energy dissipation. Compared to traditional inorganic filler systems, these deformable PNPs exhibit exceptional compatibility and uniform dispersion, endowing the PNPs‐filled ENCs with high mechanical strength, elongation at break, toughness, and low hysteresis loss. Moreover, the dynamic covalent bonds both in the matrix and interface impart excellent reprocessability and recyclability at elevated temperature, such as maintaining 88% of the mechanical performances after ten recycling cycles. This work puts forward a high additional value approach to produce PNPs, which are compounded with elastomer matrix with covalent adaptable networks to successfully balance the long‐standing irreconcilable elasticity, reinforcement, and recycling, thus opening a new avenue for the development of next generation high performance and eco‐friendly ENCs.