Half titanocenes (CpCH 2 CH 2 O)TiCl 2 1 and (CpCH 2 CH 2 OCH 3 )TiCl 3 2, activated by methylaluminoxane are tested in sty-rene-1,3-butadiene copolymerization. The titanocene 1 is able to copolymerize styrene and 1,3-butadiene, with a facile procedure, to give products with high molecular weight. The analysis of microstructure by 13 C-NMR reveals that the styrene homose-quences in copolymers are in syndiotactic arrangement, while the butadiene homosequences are, prevailingly, in 1,4-c/s configuration, according with behavior of 1 in the homopolymerizations of styrene and 1,3-butadiene, respectively. The reactivity ratios of copolymerization are estimated by diad composition analysis. All obtained copolymers have r 2 × r 2 values much larger than 1, indicating blocky nature of homosequences. The structural characterization by wide-angle X-ray powder diffraction and differential scanning calorimetry indicates that all copolymers are crystalline, with T m varying from 171 to 239 °C, depending on the styrene content. The titanocene 2 did not succeed in styrene-1,3-butadiene copolymerization, giving rise to a blend of homopoly-mers. Compounds 1 and 2 were also tested in the polymerization of several conjugated dienes, and the obtained results were very useful to rationalize the behavior of both catalysts in the copoly-merization of styrene and butadiene. © 2010 Wiley Periodicals, Inc.

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