New elastomers by metallocene catalysis

Elastomers with new microstructures such as ethene propene diene terpolymers (EPDM), polybutadiene (PB) and polyisoprene, can be synthesized by metallocene or other single site catalysts. EPDM elastomers show a narrow molecular weight distribution, low transition metal concentration and mainly 1,2-insertion of the propene units. Polybutadienes are prepared with high efficiency by different half-sandwich titanium chlorides or fluorides and methylalumoxane as cocatalyst. Di- or trimethyl substituted cyclopentadienyltitanium trihalogenides are the most active compounds with activities of about 700 kg polybutadiene/mol Ti·h. These catalysts produce polybutadiene with an interesting microstructure which consists of 80% cis, 1% trans and 19% vinyl structures.