ABSTRACT
Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276 10.3 Control of Polypropylene Molecular Weight by Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 10.4 Chain-End Functionalized Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
10.4.1 Zinc Alkyl-Terminated Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 10.4.2 Silane-Terminated Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 10.4.3 Borane-Terminated Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 10.4.4 Styrene-Terminated Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 10.4.5 Functionalized Styrene-Terminated Polypropylene. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 10.4.6 Allyl Monomer-Terminated Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
10.5 Applications of Chain-End Functionalized Polypropylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 10.5.1 Diblock Copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 10.5.2 Polypropylene/Clay Nanocomposites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
10.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292 References and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
The intense research interest in tactic control of metallocene-mediated propylene polymerization has provided a tremendous amount of detail regarding the mechanism of polymerization,1−4 including active site structure, the regioselectivity and stereoselectivity of propylene coordination and insertion, and the relationship between catalyst symmetry and polymer microstructure and properties. Nevertheless, chain release mechanisms, usually involving various chain transfer reactions, have received less attention. Some reports5−7 focus on the control of catalyst activity, polymer molecular weight, and saturated polymer chain-end structure by introducing hydrogen transfer agents using different metallocene catalysts.
