Interfacial Boron–Nitrogen Coordination Enables Vitrimer Nanocomposites with Decoupled Creep Resistance and Reprocessability

Vitrimers, a class of covalent adaptable networks (CANs), feature thermally triggered dynamic bond exchange to enable reprocessing, yet they suffer severe creep deformation, creating an inherent trade-off between service stability and malleability. Incorporating rigid silica nanofillers suppresses creep by limiting polymer chain mobility, however, high filler loading impedes dynamic bond exchange and compromises reprocessability. To address this dilemma, we construct boron–nitrogen (B–N) coordination at the filler–matrix interface by introducing amine-functionalized silica (SiO2@N) into a boronic ester vitrimer (BEV) matrix. The interfacial B–N coordination acts as dual-functional sites: it strengthens interfacial adhesion to lock chain segments and improve room-temperature creep resistance, while unlocking and catalyzing boronic ester exchange to accelerate high-temperature network rearrangement. A series of characterizations were performed to verify successful preparation of uniformly dispersed nanocomposites with interfacial B–N coordination. Compared with bare silica-filled counterparts, optimized BEV-10Si@N exhibited higher tensile strength, modulus, and glass transition temperature, a broader linear viscoelastic region, and a lower stress relaxation activation energy (25.04 kJ/mol), simultaneously boosting room-temperature creep resistance and high-temperature reprocessability. When utilized as hot-melt adhesives, BEV-10Si@N delivered a maximum lap shear strength of 8.0 MPa with a failure transition from interfacial separation to cohesive fracture. After three thermal compression reprocessing cycles, it retained nearly 84% of its initial bonding strength, whereas unmodified BEV-10Si underwent severe strength degradation caused by cumulative interfacial damage. This interfacial coordination strategy effectively decouples the mutually exclusive creep resistance and reprocessability of vitrimer nanocomposites, providing a facile, sustainable route toward high-performance recyclable hot–melt adhesives.