Nanoscale dispersion-property Nexus in natural rubber Composites: Synergistic effects of HMDS and PVAc for high-performance tire applications

Nano-silica with dual-layer surface modification -comprising short-chain HMDS (hexamethyldisilazane) chemical grafting and long-chain PVAc (polyvinyl acetate) encapsulation was synthesized through liquid-phase in-situ surface modification technology. This amphiphilic nano-silica was subsequently employed in the fabrication of high-performance tire composites using a fully-formulated wet mixing process. The uniquely structured amphiphilic silica acts as an efficient emulsifier, significantly enhancing the dispersion of non-polar rubber additives in aqueous media. The dispersion and aggregation behaviors of nanoparticles within the rubber matrix were systematically characterized using TEM, SEM, and AFM analyses. The HMDS/PVAc dual-layer modified nano-silica established a sophisticated interfacial architecture with the rubber matrix, which played a critical role in the performance enhancement of the composite. At optimal modification levels (15 wt% HMDS, 2.5 wt% PVAc), the resulting composite demonstrated remarkable improvements: a 47.4 % improvement in wet-skid resistance and a 59.6 % increase in wear resistance compared to the unmodified silica system (Si–H00–P00/NR). These enhancements outperform those achieved with conventional single-modification strategies. The superior performance is attributed to the synergistic effect of HMDS-induced surface polarity reduction and PVAc-mediated interfacial adhesion. This study highlights the potential of nanoscale amphiphilic interface engineering as a scalable materials platform for next-generation tire materials that meet the dual demands of high safety and environmental sustainability.