Polymers via Late Transition Metal Catalysis

Cycloaliphatic Polymers via Late Transition Metal Catalysis 

Early work at Mitsui Petrochemicals concentrated on copolymerization of the multicyclic olefin dimethano-octahydronaphthalene (DMON, structure II (Ri = R2=H) in Fig. 4.1), using soluble vanadium catalysts [4] that eventually led to the commercialization of Apcl polyolefins [5]. Later, the utility of metallocene catalysts for cyclic olefin copolymerization was recognized by both Mitsui and Hoechst [6]. This led to the joint development of the Topas line of polyolefins [7], now being marketed by Ticona. 

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  

There are three different mechanisms by which the cyclic olefin norbornene can be polymerized to reasonably high molecular weights ring-opening metathesis polymerization (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]. 

For these reasons relatively little attention is given to ROMP technology in this review. 

---

I 4 Cycloaliphatic Polymers via Late Transition Metal Catalysis... 

I 4 Cycloaliphatic Polymers via Late Transition Metal Catalysis Ni(O2CR)2 + 9 BFj EtsO + lOAlEt,... 

Goodall BL (2003) Cycloaliphatic polymers via late transition metal catalysis. In Rieger B, Baugh LS, Kacker S, Striegler S (eds) Late transition metal polymerization catalysis. Wiley-VCH, Weinheim, p 101... 

In 1996, Brookhart and co-workers developed a remarkable class of Pd complexes with sterically encumbered diimine ligands (Scheme 4, S4-1, S4-2, S4-4, and S4-5). These examples are capable of mediating the co-polymerization of ethylene with methyl acrylate (MA) to furnish highly branched PE with ester groups on the polymer chain ends by a chain-walking mechanism (Scheme 10). " This represents the first example of transition metal-catalyzed ethylene/MA co-polymerization via an insertion mechanism. The mechanism for co-polymerization is by 2,1-insertion of MA and subsequent chelate-ring expansion, followed by the insertion of ethylene units. The discovery of these diimine Pd catalysts has stimulated a resurgence of activity in the area of late transition metal-based molecular catalysis. Recently, the random incorporation of MA into linear PE by Pd-catalyzed insertion polymeriza-... 

---