Study on the structure, morphology, and properties of end-functionalized star-shaped solution-polymerized styrenebutadiene rubber

Three kinds of star-shaped solution-polymerized styrenebutadiene 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 (SiO2)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 SiO2 powder in the ES-SSBR was higher than that in the S-SSBR. SiO2-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 SiO2, respectively. Accordingly, ES-SSBR was a remarkable energy-saving elastomer. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013