Molecular Insights Into the Barrier and Reinforcement Mechanisms of <scp>HNBR</scp> / <scp>SWCNT</scp> Composites: A Combined Experimental and Molecular Dynamics Study

ABSTRACT To develop high‐performance sealing materials for harsh high‐temperature and high‐pressure oil‐gas environments in tank breather valves, this study incorporated single‐walled carbon nanotubes (SWCNTs) into hydrogenated nitrile butadiene rubber (HNBR). The systematic investigation of SWCNT content (0–2 phr) revealed that at a critical 2 phr loading, SWCNTs can significantly accelerate vulcanization (t90 reduced by 12.6%), enhancing crosslink density (17.7%) and modulus (141%), while reducing gas permeability by over 50% and suppressing oil‐swelling (18%) and thermal‐oxidative aging (99.4% tear strength retention). Molecular dynamics simulations elucidated the mechanism: strong interfacial interaction (~128 eV) restricts polymer chain motion (MSD reduced 36%), fundamentally inhibiting molecular diffusion (oil diffusion coefficient reduced &gt; 60%). This work provides critical formulation and theoretical guidance for designing extreme‐environment rubber seals.