Study on the structure, morphology, and properties of end‐functionalized star‐shaped solution‐polymerized styrene–butadiene rubber

Abstract Three kinds of star‐shaped solution‐polymerized styrene–butadiene rubber (S‐SSBR) were synthesized by living anionic polymerization using a self‐made multifunctional organic lithium initiator. One was S‐SSBR with 100% coupling degree. Others were the functionalized S‐SSBR which had macromolecular chain‐free ends terminated directly (ES‐SSBR‐1), and macromolecular chain terminated after dissociation in the polymerization solution (ES‐SSBR‐2) by 3‐chloropropyl trimethoxy siloxane. The molecular structure parameters of three kinds of SSBR were determined and the end‐functionalized efficiency was calculated. The rheological properties, mechanical properties, and dynamic mechanical properties of ES‐SSBR and S‐SSBR composites filled with silica (SiO 2 )–carbon black (CB) were investigated. The morphology was observed by transmission electron microscopy and high‐resolution transmission electron microscopy, and the dispersion of the two kinds of filler in the composites was distinguished by X‐ray energy spectrometry. The results showed that the mixing speed of hydrophilic SiO 2 powder in the ES‐SSBR was higher than that in the S‐SSBR. SiO 2 ‐CB/ES‐SSBR composites presented excellent mechanical properties, high wet‐skid resistance, and low rolling resistance. Two kinds of nanofiller in the ES‐SSBR exhibited outstanding doping nanometer dispersion and good distribution, which indicated that after being coupled and end‐functionalized, the two free ends of the macromolecular chains formed chemical bonding with the surface chemical groups of CB and SiO 2 , respectively. Accordingly, ES‐SSBR was a remarkable energy‐saving elastomer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013