Dual functions of inverse vulcanized copolymers as both vulcanizator and interfacial modifier for improving the mechanical properties of silica reinforced rubber composites

Inverse vulcanization provides a facile but effective methodology to create sulfur-based polymers with diverse applications by utilization of element sulfur, a massive waste product from petroleum industry. An integration of functional groups into sulfur-based polymers may inject new vitality for the traditional discipline of rubber composites, though the examples remain limited. Herein, we reported the synthesis of polysulfur copolymers (STs) via one- or two-step methods by inverse vulcanization of sulfur and triethoxyvinylsilane (TEVS) and their function mechanism in silica-filled diene rubber composites. Owing to the presence of polysulfide and multiple alkoxysilyl moieties, STs could provide two functions of vulcanizator and interfacial modifier through the reaction with the rubber chains and silica, enabling the crosslinking of rubber and uniform dispersion of silica. Importantly, ST-modified composites exhibited more uniform silica dispersion and stronger interfacial interaction than sulfur cross-linked BR/silica composites modified with conventional coupling agents, thus leading to more enhancements of the mechanical properties. Moreover, the mechanism of ST copolymers in the silica filled diene rubber composites was proposed.