Synergistic Reinforcement of Compression Set Resistance in Silicone Rubber by Dry‐Modified Silica Nanoparticles and Silicone Resin

ABSTRACT Compression set of liquid silicone rubber (LSR) gaskets critically challenges the long‐term operational stability of proton exchange membrane fuel cells (PEMFCs). Conventional silica nanoparticles suffer from poor interfacial compatibility and solvent‐induced agglomeration. Herein, a high‐performance silicone rubber seal is developed via solvent‐free synergistic dry modification of silica nanoparticles using vinyltrichlorosilane (VTCS) and hexamethyldisilazane (HMDS) alongside vinyl MQ (VMQ) silicone resin. This simple, high‐purity dry modification overcomes the poor flowability of single‐VTCS treatment and the weak reinforcement of single‐HMDS treatment. Specifically, VTCS supplies reactive vinyl sites (–CH═CH 2 ) to form a robust crosslinked network, while HMDS supplies methyl groups (–CH 3 ) to lower surface energy to ensure high matrix flowability and dispersion. Consequently, the chemical interfacial bonding effectively suppresses inelastic chain slippage under sustained compression. The resulting composite exhibits an exceptionally low compression set of 1.85% (under 25% compression at 95°C for 24 h), dropping markedly from 14.57% for the unmodified counterpart, alongside a tensile strength of 2.32 MPa. This work offers critical material support for enhancing PEMFC seal reliability and longevity.