Functional metathesis-based polymerization

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]. 

Remarkable development over the last 10-15 years in the synthesis of well-defined functional-group-tolerant ruthenium carbenes (Grubbs-related catalysts) also caused real development of the metathesis-based reactions in organosilicon polymers. For recent reviews on metathesis of organosilicon compounds see Refs. [6,7]. Unsaturated organosilicon polymers can be synthesized via ruthenium carbene catalyzed ring-opening metathesis polymerization (ROMP) of silylsubstituted cycloalkenes (Eq. 113). 

Acyclic diene metathesis (ADMET) is a step-growth polycondensation reaction for the polymerization of o -dienes 729 The process is catalyzed by the same metal alkylidene initiators used for ROMP, and is driven by the removal of ethylene from the system (Scheme 13). Both molybdenum and ruthenium-based initiators have been used to prepare a variety of materials including functionalized polyethy-... 

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-... 

M.A. Hillmyer, W.R. Laredo, and R.H. Grubbs, Ring-opening metathesis polymerization of functionalized cyclooctenes by a ruthenium-based metathesis catalyst, Macromolecules, 28(18) 6311-16,1995. 

Chloromethyl polystyrene can be converted to a free-radical initiator by reaction with 2,2,6,6-tetramethylpipcridinc-/V-oxyl (TEMPO). Radical polymerization of various substituted alkenes on this resin has been used to prepare new types of polystyrene-based supports [123]. Alternatively, cross-linked vinyl polystyrene can be copolymerized with functionalized norbornene derivatives by ruthenium-mediated ringopening metathesis polymerization [124],... 

ADMET polymerization has been used to integrate silicon into linear and network hydrocarbon polymers in an attempt to produce novel materials with enhanced thermal and mechanical stability. While ADMET has been used to produce copolymeric architectures unattainable through conventional methods, application of this polymerization to synthesis is feasible only if the silicon-based functionality does not inhibit metathesis. This research, initiated in the early 1990s by Wagener and colleagues, has shown that the silane and siloxane... 

Recent developments in ADMET polymerization and its use in materials preparation have been presented. Due to the mild nature of the polymerization and the ease of monomer synthesis, ADMET polymers have been incorporated into various materials and functionaUzed hydrocarbon polymers. Modeling industrial polymers has proven successful, and continues to be appUed in order to study polyethylene structure-property relationships. Ethylene copolymers have also been modeled with a wide range of comonomer contents and absolutely no branching. Increased metathesis catalyst activity and functional group tolerance has allowed polymer chemists to incorporate amino acids, peptides, and various chiral materials into metathesis polymers. Sihcon incorporation into hydrocarbon-based polymers has been achieved, and work continues toward the application of latent reactive ADMET polymers in low-temperature resistant coatings. 

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