Preparation, structure, and properties of solution-polymerized styrene-butadiene rubber with functionalized end-groups and its silica-filled composites

With anionic polymerization, the solution-polymerized styrene-butadiene rubber (SSBR) and solution-polymerized styrene-butadiene rubber with alkoxysilane-functionalization at two ends of macromolecular chains (A-SSBR) were synthesized by dilithium as initiator. The occurrences of end-group functionalization and condensation reaction were confirmed, but also the molecular structure parameters and end-functionalized efficiency of A-SSBR grafted alkoxysilane groups onto the ends of its macromolecular chains were calculated through the characterizations. By this novel structural modification, there were chemical bondings rather than conventional physical adsorption between silica and rubber matrix. This novel technology was beneficial to not only immobilizing the free chain ends to decrease the amount of macromolecular chainsʹ free terminals, but also chemically bonding the rubber chains on the surfaces of silica particles to enhance the filler-polymer interaction significantly. Furthermore, the covering layer of end-functionalized macromolecular chains around the silica particles was conducive to reducing the silica agglomeration and improving the silica dispersion. The structures, morphologies, and properties of SiO2/SSBR and SiO2/A-SSBR composites prepared by co-coagulation and mechanical blending, were investigated. The results showed that SiO2/A-SSBR composites behaved better comprehensive performances including higher wet skid resistance and lower rolling resistance than SiO2/SSBR composites. Consequently, A-SSBR was an ideal material for the green tire treads.