Ring opening metathesis polymers

Interest in cyclic olefin (co)polymers has increased dramatically over the past decade. This is because this class of polymers displays many attractive properties such as high thermal stability, high optical transparency, low dielectric constants, and low moisture absorption. Thus, these polymers can potentially be utilized in many electronic and optical applications. Although cyclic olefin (co)polymers typically include ring-opening metathesis polymers, vinyl-addition homopolymers, and vinyl-addition co-polymers with acyclic co-monomers such as ethylene, we will mainly deal with vinyl-addition homo- and co-polymers in this section. 

T. Sunaga, M. Okita, and T. Asanuma, Preparation of hydrogenated product of cyclic olefin ring-opening metathesis polymer, US Patent 6197 894, assigned to Mitsui Chemicals, Inc. (JP), March 6, 2001. 

Ring-opening metathesis polymer sphere-supported seco-porphyrazines efficient and recyclable photooxygenation catalysts. Journal of Organic Chemistry, 71... 

Fuchter, M.J., Hoffman, B.M. and Barrett, A.G.M. (2006) Ring-opening metathesis polymer sphere-supported seco-porphyrazines efficient and recyclable photooxygenation catalysts. Journal of Organic Chemistry, 71 (2), 724-729. 

Apart from the synthesis of such simple compounds, far more complex entities in the form of high molecular weight polymers reflect the bulk of current metathesis applications. A representative example along these lines is the synthesis of the ring-opened metathesis polymer 22 of norbomene (20) which proceeds as shown in Scheme 7b. Over 45,000 tons of this polymer are produced annually by this, so called, Norsorex process." Among different potential precursors for ROMP, norbomene is particularly easy to convert into polymers because the metathesis relieves the strain of the ring system. Moreover, living norbomene polymer (with the carbene still in place as in 21) can become a scaffold... 

BLOCKINESS AND TACTICITY IN RING-OPENED METATHESIS POLYMERS... 

A systematic procedure based on norbornene, norbornadiene and their 7-methyl derivatives is described for the determination of the cis content, blockiness and tacticity of ring-opened metathesis polymers (ROMP). In this way the factors determining tacticities and stereoselectivities can be established and applied to the rapidly growing families of well-defined Schrock and Grubbs initiators. 

Al-Samak, B. Amir-Ebrahimi, V. Carvill, A. G Hamilton, J. G Rooney, J. J.. Determination of the tacticity of ring-opened metathesis polymers of norbornene and norbornadiene by C NMR spectroscopy of their hydrogenated derivatives. Polym. Int. 1996, 41, 85-92. 

L. Delaude, A. Demonceau and A.F. Noels, Probing the Tacticity of Ring-Opened Metathesis Polymers of Norbornene and Norbornadiene Diesters by NMR Spectroscopy , p. 249... 

Aqueous ring-opening metathesis polymerization (ROMP) was first described in 1989 (90) and it has been appHed to maleic anhydride (91). Furan [110-00-9] reacts in a Diels-Alder reaction with maleic anhydride to give exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3—dicarboxylate anhydride [6118-51 -0] (24). The condensed product is treated with a soluble mthenium(Ill) [7440-18-8] catalyst in water to give upon acidification the polymer (25). Several apphcations for this new copolymer have been suggested (91). 

A drawback to the Durham method for the synthesis of polyacetylene is the necessity of elimination of a relatively large molecule during conversion. This can be overcome by the inclusion of strained rings into the precursor polymer stmcture. This technique was developed in the investigation of the ring-opening metathesis polymerization (ROMP) of benzvalene as shown in equation 3 (31). 

Lu H, Wang J, Lin Y, Oieng J (2009) One-pot synthesis of brush-like polymers via integrated ring-opening metathesis polymerization and polymerization of amino acid N-carboxyanhy-drides. J Am Oiem Soc 131 13582-13583... 

Catalysts with an unsymmetrical NHC ligand featuring a vinylic side chain have the unique ability to metathesise their own ligand to form a metaUacycle as shown in Scheme 3.7 [119], Ring opening metathesis will then incorporate the monomers, e.g. cyclooctene, into that cycle until a cyclic polymer is cleaved by another intramolecular metathesis step. The catalyst is recovered and can restart this endless route to cyclic polymers [121]. 

Controlling the exact architectnre of polymers has always attracted attention in macromolecular chemistry. Snccessfnl synthesis of alternating copolymers nsing ring opening metathesis polymerisation is of great interest also from a mechanistic perspective. NHC ligands were fonnd to be ideal to tune the selectivity of the metathesis initiators. 

Wolfe and Wagener have developed main-chain boronate polymers (59) (Fig. 38) by the acyclic diene metathesis (ADMET) polymerization of symmetrical ,oj-dienes, containing both methyl- and phenyl-substituted boronate functionalities using Mo and Ru catalysts.84 The ring-opening metathesis polymerization (ROMP) of several norbornene monomers containing methyl- and phenyl-substituted boronates into... 

We have reported the first example of a ring-opening metathesis polymerization in C02 [144,145]. In this work, bicyclo[2.2.1]hept-2-ene (norbornene) was polymerized in C02 and C02/methanol mixtures using a Ru(H20)6(tos)2 initiator (see Scheme 6). These reactions were carried out at 65 °C and pressure was varied from 60 to 345 bar they resulted in poly(norbornene) with similar conversions and molecular weights as those obtained in other solvent systems. JH NMR spectroscopy of the poly(norbornene) showed that the product from a polymerization in pure methanol had the same structure as the product from the polymerization in pure C02. More interestingly, it was shown that the cis/trans ratio of the polymer microstructure can be controlled by the addition of a methanol cosolvent to the polymerization medium (see Fig. 12). The poly(norbornene) prepared in pure methanol or in methanol/C02 mixtures had a very high trans-vinylene content, while the polymer prepared in pure C02 had very high ds-vinylene content. These results can be explained by the solvent effects on relative populations of the two different possible metal... 

Since one of the substrates is a cyclic alkene there is now the possibility of ring-opening metathesis polymerisation (ROMP) occurring which would result in the formation of polymeric products 34 (n >1). Since polymer synthesis is outside the scope of this review, only alkene cross-metathesis reactions resulting in the formation of monomeric cross-coupled products (for example 30) will be discussed here. 

Fig.4A,B. Ring-opening metathesis polymerization (ROMP) A Structures of organometal-lic initiators that have been used in ROMP to generate neobiopolymers. B General pathway for polymer synthesis using ROMP. Molybdenum-initiated reactions are typically capped with aldehydes and ruthenium-initiated with end ethers.

Living organisms, fermentation by, 11 1-2 Living polymerization, 23 728 of acrylic ester monomers, 1 386 of methacrylic ester polymers, 16 291 Living polymers, 24 705 Living ring-opening metathesis... 

See also ROM polymers Ring-opening metathesis polymerization (ROMP) reaction, 20 413 Ring-opening polymerization (ROP), 24 271, 29 816-817, 23 702,... 

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