Polymer synthesis metathesis polymerization

A potential drawback of all the routes discussed thus far is that there is little control over polydispersity and molecular weight of the resultant polymer. Ringopening metathesis polymerization (ROMP) is a living polymerization method and, in theory, affords materials with low polydispersities and predictable molecular weights. This methodology has been applied to the synthesis of polyacctylcne by Feast [23], and has recently been exploited in the synthesis of PPV. Bicyclic monomer 12 [24] and cyclophane 13 [25) afford well-defined precursor polymers which may be converted into PPV 1 by thermal elimination as described in Scheme 1-4. 

Buchmeiser, M.R., Schuler, N., Schottenberger, H., Kohl, I., Hallbrucker, A. and Wurst, K. (2000) Ferrocenyl- and Octamethylferrocenyl-substituted Phenylene-vinylene-, Thienylenevinylene- and 1,1 -Ferrocenylenevinylene Spaced Ethynes Synthesis, Metathesis Polymerization and Polymer Properties, Designed Monomers Polymers, in press. 

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). 

Olefin metathesis, an expression coined by Calderon in 1967,1 has been accurately described in Ivin and Mol s seminal text Olefin Metathesis and Metathesis Polymerization as the (apparent) interchange of carbon atoms between a pair of double bonds (ref. 2, p. 1). This remarkable conversion can be divided into three types of reactions, as illustrated in Fig. 8.1. These reactions have been used extensively in the synthesis of a broad range of both macromolecules and small molecules3 this chapter focuses on acyclic diene metathesis (ADMET) polymerization as a versatile route for the production of a wide range of functionalized polymers. 

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... 

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.

K. Nomura, H. Morimoto, Y. Imanishi, Z. Ramhani, and Y. Geerts, Synthesis of high molecular weight rra i-poly(9,9-di- -octylfluorene-2,7-vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts, J. Polym. Sci., Part A Polym. Chem., 39 2463-2470, 2001. 

Olefin metathesis technology, in polymer synthesis, 26 944-948 Olefin oligomerization, 16 111 Olefin oxides, alkanolamines from (with ammonia), 2 122-140 Olefin polymerization, organic titanium compounds in, 25 122 Olefin(ic) polymers, 17 699-709 ethylene-propylene elastomers, 17 705-707... 

Dalphond J, Bazzi H, Kahrim K, Sleiman H. Synthesis and self-assembly of polymers containing dicarboximide groups by living ring-opening metathesis polymerization. Macromol Chem Phys 2002 203 1988-1994. 

Pontrello JK, Allen MJ, Underbakke ES, Kiessling LL. Solid-phase synthesis of polymers using the ring-opening metathesis polymerization. J Am Chem Soc 2005 127 14536-14537. 

Moore, J. S. Transition Metals in Polymer Synthesis Ring-opening Metathesis Polymerization and Other Transition Metal Polymerization Techniques. In Comprehensive Organometaltic Chemistry // Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Elsevier Oxford, 1995 Vol. 12, pp 1209-1232. 

Kiessling, L. L. Owen, R. M. Synthesis and Applications of Bioactive Polymers Generated by Ring-opening Metathesis Polymerization. 

The synthesis of polyoctenamer has been commercialized by Huels.150 In contrast with the transformation of cyclooctene to 1,9-decadiene [Eq. (12.31)], homogeneous catalyst compositions, such as WClg + EtAlCl2, are used to promote ring-opening metathesis polymerization of cyclooctene. A polymer of narrow molecular-weight distribution with high trans content (55-85%) called Vestenamer is produced and used as blend component in different rubbers and thermoplastics. 

The Durham precursor route to polyacetylene is an excellent example of the application of organic synthesis to produce a precursor polymer whose structure is designed for facile conversion to polyacetylene. Durham polyacetylene was first disclosed by Edwards and Feast, working at the University of Durham, in 1980 227). The polymer (Fig. 6 (I)) is effectively the Diels-Alder adduct of an aromatic residue across alternate double bonds of polyacetylene. The Diels-Alder reaction is not feasible, partly for thermodynamic reasons and partly because it would require the polymer to be in the all m-conformation to give the required geometry for the addition to take placed 228). However, the polymer can be synthesised by metathesis polymerization of the appropriate monomer. 

Kricheldorf, H. R., Metathesis Polymerization of Cycloolefins , in Handbook of Polymer Synthesis, M. Dekker, New York, 1992, Part A, pp. 433-479. 

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). 

Sutthasupa S, Shiotsuki M, Sanda F (2010) Recent advances in ring-opening metathesis polymerization, and application to synthesis of functional materials. Polym J 42 905-915... 

---