Ring-opening metathesis polymerization Group 8 initiators

The living character of the ring opening metathesis polymerization described earlier in this review enables a simple preparation of functionalized norbornene-based monoliths. Adding one more in situ derivatization step that involves functional norborn-2-ene and 7-oxanorborn-2-ene monomers that react with the surface-bound initiator, the pores were provided with a number of typical functional groups such as carboxylic acid, tertiary amine, and cyclodextrin [58,59]. 

Olefin metathesis catalysts based on ruthenium have been shown to exhibit a quite good tolerance to a variety of functional groups. The ring opening metathesis polymerization of strained, cyclic olefins initiated by group VIII salts and coordination complexes in aque-... 

Figure 7.12 Ring-opened metathesis polymerization (ROMP) of cyclooctene. Note that ROMP could be initiated with any M=CR2, and for a living polymer the end group will be CH=CR2.

NCA polymerization allows also the preparation of comb-shaped polymers. Lu et al. reported the one-pot synthesis of comb-shaped polymers via ring-opening metathesis polymerization and NCA polymerization (Fig. 18). The authors used a norbomene derivative with a trimethylsilyl-protected amine to prepare a polymer with pendant trimethylsilyl amine groups, which can be used as initiators for the NCA polymerization (see. Fig. lb) [17]. 

Schrock, Wrighton, and coworkers have reported that ring-opening metathesis polymerization (ROMP) of norbomene monomers fhnctionalized with ferrocenyl groups allowed for the isolation of polymers such as 55-58. Alternatively, polynorbornenes capped with ferrocenyl units could be produced by using a molybdenum initiator functionalized with ferrocene. When this polymerization reaction was terminated through the addition of octamethyl-ferrocenecarboxaldehyde, low molecular weight polymers such as 58 were isolated. 

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