Aminopolysulfides as Interfacial Regulators for Low-Hysteresis and Fatigue-Resistant Silica/Rubber Nanocomposites

Silane-mediated interfacial modification of silica-filled nanocomposites, despite being a standard practice, suffers from the intrinsic inefficiency of the silanization reaction, severely limiting composite performance. Herein, we report amino-functionalized polysulfides (AFPSs) with tunable amino contents as interfacial regulators that address this limitation. Experimental and theoretical studies reveal that the amino groups concurrently interact with silica and silane bis(triethoxysilylpropyl)tetrasulfide (TESPT) via hydrogen bonds, thermodynamically recruiting TESPT to the silica surface and kinetically activating silanol groups to lower the silanization energy barrier. By enabling the polysulfide-mediated grafting of amino moieties onto rubber chains, AFPS incorporation establishes an auxiliary coupling pathway and promotes silanization within the nanocomposites. Multiscale characterizations disclose that silica dispersion is progressively improved and interfacial adhesion is systematically enhanced with increasing amino content in AFPS. Consequently, AFPS-modified nanocomposites demonstrate superior mechanical properties and fatigue resistance, along with reduced hysteresis loss, substantially lowering tire energy consumption while extending the service life.