Cyclopentadienyl rings metallocene-based polymers

In Chapter 2, the chemistry of metallocene-based polymers was reviewed. Herein, other classes of polymers containing cyclopentadienyl rings coordinated to transition metal moieties are described (5). The chemistry of polymers containing 4-membered rings coordinated to transition metal moieties has been investigated however, there are fewer reports on the synthesis and characterization of this type of polymer (6). Within each of these classes of polymers, the synthesis of dendrimeric and/or star-shaped polymers will also be highlighted. 

Metallocene catalysis is an alternative to the traditional Ziegler-Natta vanadium-based catalysis for commercial polyolefin production, e.g. the use of metallocene-catalyzed ethylene alpha-olefin copolymers as viscosity index modifiers for lubricating oil compositions [23]. The catalyst is an activated metallocene transition metal, usually Ti, Zr or Hf, attached to one or two cyclopentadienyl rings and typically activated by methylaluminoxane. Metallocene catalysis achieves more stereo-regularity and also enables incorporation of higher alpha-olefins and/or other monomers into the polymer backbone. In addition, the low catalyst concentration does not require a cleanup step to remove ash. 

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