Crystallinity trans-styrene-butadiene

Styrene - Crystalline Polystyrene 85% Styrene - Styrene Butadiene Copolymer 45% Styrene Styrene Butadiene Copolymer 30% Styrene Styrene Butadiene Copolymer 23% Styrene - Styrene Butadiene Copolymer 5% Styrene - Styrene Butadiene Copolymer Cis Polybutadiene Cis-Trans Polybutadiene... 

The diene double bond in equation (9.94) may be either cis or trans. The cis products all have lower glass transition temperatures and/or reduced crystallinity, and they make superior elastomers. A random copolymer of butadiene and styrene is polymerized to form SBR (styrene-butadiene rubber). This copolymer forms the basis for tire rubber (see below). The trans materials, such... 

As was found for the polymerization of styrene, CpTiCT/M AO and similar half-sandwich titanocenes are active catalysts for the polymerization of conjugated 1,3 dienes (Table XX) (275). Butadiene, 1,3-pentadiene, 2-methyl-l,3-pentadiene, and 2,3-dimethylbutadiene yield polymers with different cis-1,4, trans-1,4, and 1,2 structures, depending on the polymerization temperature. A change in the stereospecificity as a function of polymerization temperature was observed by Ricci et al. (276). At 20°C, polypen-tadiene with mainly ds-1,4 structures was obtained, whereas at -20°C a crystalline, 1,2- syndiotactic polymer was produced. This temperature effect is attributed to a change in the mode of coordination of the monomer to the metallocene, which is mainly cis-rf at 20°C and trans-rj2 at -20°C. 

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