Toughening\nRubber by In Situ Construction of Hierarchical\nCoordination Complexes with a Sulfur-Based Ionomer

Programming energy-dissipating units into polymers is\nan effective\nmethod to improve the toughness; however, the state-of-art approaches\nusually involve complicated chemistry manipulation and multistep process.\nIn this contribution, we report a brand-new way to toughen styrene–butadiene\nrubber (SBR) by incorporating a sulfur-based ionomer to construct\nhierarchical coordination complexes. Specifically, the ionomer P(TA-S)/Fe\ncontaining polysulfide backbones and iron–carboxylate complexes\nwas synthesized through the copolymerization of thioctic acid and\nsulfur, followed by introducing ferric chloride. Due to the reaction\nbetween polysulfide fragments in P(TA-S)/Fe and SBR, the incorporation\nof P(TA-S)/Fe enabled the chemical cross-linking of SBR and grafting\nof iron–carboxylate complexes onto SBR chains. The grafted\niron–carboxylate complexes aggregated and formed a phase separate\nstructure within SBR, which provided a multilevel energy-dissipating\nmechanism and consequently led to an integration of enhanced ultimate\nstrength, modulus, and fracture toughness of SBR.