Cycloaliphatic Polymers via Late Transition Metal Catalysis - Late Transition Metal Polymerization Catalysis - page 101

This review will attempt to cover all of these polymer types, in particular with
reference to developments involving late transition metals. However, there will be
a major emphasis on norbornene polymers for a variety of reasons:
Norbornene monomers can be (co-)polymerized by a variety of polymerization
pathways, offering significant diversity.
Norbornenes represent a wide variety of monomers and hence polymers and ap-
plication areas.
This area is developing into a number of possible commercial applications,
thanks in part to some pioneering work carried out at my old group at the B. F.
Goodrich Company, as well as a number of other companies using both early
and late transition metal catalysts.
There are three different mechanisms by which the cyclic olefin norbornene can
be polymerized to reasonably high molecular weights: ring-opening metathesis po-
lymerization (or ROMP), vinyl addition copolymerization with acyclic olefins such
as ethylene, and vinyl addition homopolymerization (see Fig. 4.2). Carbocationic
and free-radical initiated polymerizations are ignored since they yield only low
molecular weight oligomers [8].
The polymerization of strained cyclic olefin monomers, such as norbornene,
finds its roots in the 1950s with the work of Andersen and Merckling [9] who
were the first to report ROMP polynorbornene. Since then, olefins such as cyclo-
pentene, cyclooctene, and norbornene have been used, with varying degrees of
commercial success, as constituents in elastomeric materials (i.e., those with rela-
tively low glass transition temperature, T g ). In this regard ROMP materials such
as Vestenamer ® (polycyclooctene) and Norsorex ® (polynorbornene) come to
mind. None of these polymers are cycloaliphatic since they are all highly unsatu-
rated, and the polymers derived from mono-cyclic olefins are linear in nature. The
polymers resulting from bicyclic and polycyclic olefins (e.g. norbornene and its
higher homologs) afford truly cycloaliphatic polymers only after hydrogenation.
Fig. 4.2 Norbornene polymerization pathways.