Synthesis of New Polyolefin Elastomers, Poly(ethylene-ter-propylene-ter-p-methylstyrene) and Poly(ethylene-ter-1-octene-ter-p-methylstyrene), Using Metallocene Catalysts with Constrained Ligand Geometry

This paper discusses two new polyolefin elastomers, i.e., poly(ethylene- ter -propylene- ter - p -methylstyrene) (EP-p-MS) and poly(ethylene- ter -1-octene- ter - p -methylstyrene) (EO-p-MS), containing “reactive” p -methylstyrene ( p -MS) groups. Both terpolymers, with a broad range of terpolymer composition, high molecular weight, narrow molecular weight, and composition distributions, have been prepared by using [C 5 Me 4 (SiMe 2 N t Bu)]TiCl 2 metallocene catalyst with constrained ligand geometry. Differential scanning calorimetry (DSC) results show no detectable melting point ( T m ) in both terpolymers containing less than 70 mol % ethylene units. The sharp glass transition temperature ( T g ) with flat base line in each DSC curve indicates homogeneous terpolymer microstructures. In general, the T g of EP- p -MS is very sensitive to the terpolymer composition (ethylene/propylene ratio and p -MS content). In the compositions with the ideal ethylene/propylene ratio ∼ 55/45, T g is almost proportional to the content of p -MS. Only with the concentration of p -MS < 2 mol % does the EP- p -MS show a low T g < −45 °C. On the other hand, the EO- p -MS system exhibits a low T g < −50 °C in a wide range of copolymer compositions, even ones with relatively high p -MS contents (>7 mol %).