Metallocene catalysis ethylene-styrene copolymers

Cyclopentadienyl ligands have become extremely important in catalysis for metal such as Ti, Zr, and Hf (Chapter 10) and in academic studies of related elements such as Ta. Ethylene polymerisation with the use of CpiTiCE (alkylated with aluminium alkyl compounds) has been known for many decades, but the intensive interest in derivatives of these compounds started in the early 1980 s following the discovery of MAO (methaluminoxane - see chapter 10) which boosted metallocene catalyst activities by several orders of magnitude. Commercial interest focussed on ethylene copolymers (LLDPE where more homogeneous comonomer incorporation resulted in greatly improved copolymer properties) and in enantiospecific polymerisations for propene, styrene, etc. 

In this section we survey the use of metallocenes as catalyst precursors for polymerizations in which the predominant monomer is not ethylene or any a-olefin. The subject of metallocenes as initiators for the cationic polymerization of vinyl monomers is dealt with elsewhere. Except for styrene, true random copolymers of the monomers in this section with alkenes are not produced because the mechanisms for polymerization of the non-olefins differ greatly from that operating in Sinn-Kaminsky catalysis. 

---