Norbomadiene, ROMP

Polymeric isoxazolines were prepared by cycloaddition of nitrile oxides to norbomadiene followed by ring-opening metathesis polymerization (ROMP) <06PLM3292 06MM3147>. 

In the Norsorex process, norbomadiene is polymerized by a ROMP type process. Polymers synthesized by ROMP have poor thermal stability and oxidative stability due to unsaturation of the main chain. They are used as thermoplastic resins or thermosetting resins. 

The ring-opened polymer of norbomadiene consists of 3,5-disubstituted cyclopentene units (94). When the concentration of these units is kept below 0.2 M the polymer remains soluble, but above this concentration, in the presence of WClg/Me4Sn (1/2), it gels. This is caused by cross-linking, brought about by the ROMP of the enchained cyclopentene... 

In the ROMP of norbomadiene and the dicyclopentadienes, the opening of the second double bond is thermodynamically less favourable than the opening of the first double bond, but nevertheless occurs if the concentration of the repeat units is somewhat above 0.2 M (see Sections 13.4.1.1 and 13.4.3). 

Grubbs-type initiators are well-defined ruthenium aUcylidenes. Compared to molybdenum- or tungsten-based Schrock catalysts, the reactivity of ruthenium-based Grubbs catalysts is somewhat different. In terms of polymer structure, ROMP of norbom-2-enes and norbomadienes using ruthenium-based systems generally results in the formation of polymers that, in most cases, predominantly contain frany-vinylene units. Polymerizations initiated by Grubbs-type initiators are best terminated by the use of ethyl vinyl ether, yielding methylidene-terminated polymers. 

ROMP polymers from silyl-substituted norbomadienes and norbornenes Hg, H2, N2, O2, C02 CH4, C2H0 85-167 22 0.1-1 [168]... 

TABLE 5. ROMP of heteroatom substituted norbomenes with carbyne tungsten (VI) complexes Cl3(dme)W=C Bu (A), ( BuO)3WsC Bu (B), Np3W=C Bu (C), nbe = norbomene, nbde = norbomadiene, reaction time 24 h, GPC Polystyrene standard solvent THE, temperature 25°C. 

Ring-opening metathesis polymerization (ROMP) has been used to prepare unsubstituted PPV via a soluble precursor. Substituted paracyclophan-l-ene (9) (24) and norbomadiene derivatives (10) (25) have been used as monomers, with... 

Abstract The presented paper is a summary of our results on synthesis and polymerization of silyl-containing norbomenes and norbomadienes via ring-opening metathesis polymerization (ROMP) and addition processes as well as ring-opening polymerization (ROP) of silacyclobutanes and disilacyclobutanes. The synthesis of heterochain and carbochain polymer families with regularly varied substituents at Si atom and various number and location Si(CH3)3-substituents has been realized. Systematic study of gas transport parameters of polycarbosilanes series of different classes allowed us to find out real eorrelations between features of chemical polymer structure and its gas separation eharacteristics. 

Ring-opening metathesis polymerization (ROMP) of silieon-containing norbor-nenes and norbomadienes (Seheme 3 and Table 1) proceeded much more slowly than in the case of unsubstituted norbomene. Nevertheless, even classical poor characterized Ru or W catalyst systems proved to be active in these reactions. We used various catalysts to obtain polymers with different content of cis- and trans-double bonds. 

Table 1. ROMP of silicon-containing norbomencs and norbomadienes...

NMR studies of the ROMP of certain 7-substitoted norbomadiene derivatives provided a remarkable example of a substituent-dependent re-gioselectivity. Scheme 16. 7-methyInorbomadiene [62] and 7-t-butoxynorbor-nadiene [77] were polymerised using a range of catalysts whereas the 7-Me derivative behaved in the expected manner with almost exclusive attack at the anti face of the molecule NMR spectra of the polymers are discussed below),... 

The exact control of polymer microstructures (e.g., tacticity and double-bond configuration) resulting from the ROMP of substituted norbomenes and norbomadienes is essential for the development of polymers with well-defined physical properties. Norbomene and norbomadiene-derived polymers could be accessed with... 

Multiblock polymeric networks are the logical extension of the homopolymer as it is essentially two or more homopolymers covalently attached in a linear fashion. For many applications, the result is rather simplistic in frmctionality. An early example of block copolymers used a titanacyclobutane to effectuate the polymerization of norbornene, norbomadiene derivatives, and cyclopentadiene into diblock or triblock hydrocarbon copolymers with PDIs of 1.08-1.14. The ROMP of cyclobutadiene using a tungsten catalyst followed by hydrogenation yielded polyethylene or instead of hydrogenation, it can be used to form diblocks and triblocks with norbomadiene." The ability to form block copolymers can be a test of the efficiency of a catalyst as was done with the third-generation Cmbbs catalyst by Stelzer in which oligomeric norbornyl monomers were used to synthesize homopolymers, diblocks. 

Generally speaking, Schrock initiators are highly active in the ROMP of a vast variety of cyclic alkenes such as substituted NBEs, norbomadienes, 7-oxanorbornenes, cyclooctatetraenes (GOTs), 1,4-CODs, etc., or polycyclic alkenes such as certain quadricyclanes. In addition, they may be used for 1-alkyne polymerization and the cyclopolymerization of 1,6-hepta-diynes. Despite the fact that they are highly sensitive... 

Similar micro structures are obtained when norbornene is replaced by norbomadiene. 5-and 6-substituted norbornene derivatives when polymerized by ROMP give more complex micro structures (Figure 11). By ROMP it is possible, more easily than by Ziegler-Natta catalysts, to polymerize norbor-nenes with polar substituents such as carbomethoxy, carboethoxy, or trifluoromethyl groups. " ... 

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