Revealing the Reinforcing Mechanism of Modified Hexagonal Boron Nitride on Mechanical and Tribological Properties of Polytetrafluoroethylene Composites: Insights From Experiments and Molecular Dynamics Simulations

The interfacial interactions between nanofillers and polymer matrices critically determine the overall performances of composites. In this study, we systematically investigated the effect of modifying hexagonal boron nitride (hBN) with 3‐aminopropyltriethoxysilane (APTES) on the mechanical and tribological performances of polytetrafluoroethylene (PTFE), using both experiment testing and molecular dynamics simulations. Mechanical and tribological tests show that, compared to neat PTFE, the APTES‐hBN/PTFE composite exhibits a 29.14% higher Young's modulus, a 25.24% higher fracture energy, a 29.15% lower coefficient of friction, and a 79.44% lower wear rate. Furthermore, APTES‐modified hBN promotes a transition in friction mechanism from adhesive wear and plastic deformation of PTFE to abrasive wear and interlaminar shear of hBN nanosheets, owing to improved dispersion and interfacial bonding. Simulation results reveal that APTES‐hBN provides the highest interfacial cohesive stress and interfacial shear stress among the modified fillers, which directly explains the enhanced stiffness, toughness, and wear resistance observed experimentally. Together, this work offers atomic‐level insights and a practical route for developing high‐performance polymer composites with superior mechanical properties and low friction and wear.