Interfacial Covalent Bonding Enables Self‐Limiting Wear in CNTFKM Composites at High Temperature

ABSTRACT Fluoroelastomers (FKM) suffer from synergistic degradation of adhesive wear and thermal oxidation under extreme thermal conditions, severely limiting their reliability in aerospace sealing applications. Herein, we demonstrate that carboxyl‐functionalized carbon nanotubes (CNTs) chemically bond with FKM molecular chains during vulcanization at 177°C, forming COC covalent linkages that reconstruct the crosslinking network and fundamentally redirect wear trajectories. This interfacial covalent architecture enables a paradigm shift from catastrophic “long‐and‐deep” adhesive grooving (pit depth: 392.2 μm) to controllable “short‐and‐wide” self‐limiting abrasion (pit depth: 238.3 μm, −39.2%), with wear volume decreased by 48.2% under 175°C reciprocating friction. Mechanistically, the high‐aspect‐ratio CNTs (> 1000) establish a tripartite reinforcement framework: (i) axial rigidity resists tensile deformation (tensile strength: 17.5 ± 0.8 MPa, +12.2%), (ii) radial bridging arrests crack propagation (tear strength: 25.9 ± 0.6 kN/m, +13.6%), and (iii) core–shell interfacial friction dissipates energy. Concurrently, the CNT network constructs efficient thermal channels (thermal conductivity: 0.3183 W/(m·K)), extending pyrolysis completion time from 29.5 to 35.8 min and suppressing localized overheating that triggers oxidative chain scission. This work establishes a chemical‐bonding‐directed design principle for elastomeric composites, providing a materials‐level solution for state‐aware sealing systems in high‐altitude aviation environments where thermal–mechanical–tribological coupling dictates service life.