Norbomene derivatives polymers

Fig. 3.31 Steric control in alternating ROMP Tendencies of norbomene and cyclooctene to give productive olefin metathesis upon coordination are illustrated by a thick arrow (preferred monomer) or a thin arrow (less favoured monomer) (a) only minor steric hindrance SlMes greatly favours the polymerisation of the strained norbomene (b) the rotating phenylethyl-group induces a steiically more congested active site, leading to preferred incorporation of the smaller cyclooctene (c) the flexible and small cyclooctene derived polymer fragment permits the incorporation of the bulky norbomene...

N. Miyaki, Y. Miyamoto, S. Fukuhara, and T. Ootsuki, Norbomene derivative and norbomene polymer obtained therefrom through ring opening polymerization, US Patent 6 846 890, assigned to JSR Corporation (Tokyo, JP), January 25, 2005. 

T. Hasan, T. Ikeda, and T. Shiono, Homo- and copolymerization of norbomene derivatives with ethene by ansa-fluorenylamidodimeth-yltitanium activated with methylaluminoxane,. Polym. Sci., Part A Polym. Chem., 45(20) 4581-4587, October 2007. 

Partially hydrogenated polymers derived from norbomene derivatives, [1], prepared by Miyaki [2] were low in birefringence, high in wavelength dependency birefringence, and excellent in transparency and heat resistance. Additional functionalized norbomene derivatives were prepared by Liaw [3],... 

The living ROMP reactions of norbomene and norbomene derivatives have been used to make a variety of polymers possessing unusual properties. Copolymerization of selected fimctionalized norbomenes with norbomene has been used to synthesize star polymers and side-chain liquid crystal polymers. This chemistry has also resulted in the preparation of phase separated block copolymers that contain uniform sized metal or semiconductor nanoparticles. The... 

While there is a general pattern of increasing as one proceeds down the tables for each monomer and approximate constancy as one proceeds across the tables, there are some interesting exceptions. Thus with RuCls the norbomene derivatives always give high-trans polymers (a = 0-0.1) but for and 7 rises to 0.25 and 0.5 respectively, presumably because of increased strain in, and therefore reactivity of, the monomer, thereby reducing the discrimination between the two L2+21 modes of addition leading to cis and trans double bond formation respectively. 

In assessing data on the proportions of cc, ct and tt pairs it is first necessary to ensure that the cis content has not been modified by the occurrence of secondary metathesis reactions. These can occur extremely rapidly with some polymer/catalyst systems. For example a polymer of cycloocta-1,4-diene initially contains no tt junctions, alternate double bonds in the polymer chain being derived from preformed cis double bonds in the monomer but under certain catalyst conditions tt junctions appear within a matter of seconds by secondary metathesis (14,15). These problems do not appear to be serious in polymers of norbomene derivatives presumably because the double bonds in the polymer are protected from secondary metathesis by the adjacent C5 rings and cannot compete when highly reactive monomer is still present. 

Table 11.7 Polymers of norbomene derivatives showing m r splitting of the trans HH olefmic resonance in the C NMR spectrum X = eATO-5-substituent, Y = e/i o-5-substituent. Catalyst RUCI3.3H2O in EtOH/PhCl at 50-70°C, except where indicated otherwise (Ivin...

Chart 3. ROMP of the norbomene-derivatives 5 to liquid crystalline polymers 6 where a indicates that n=3, b that n=5, c stands for n=9 d means n=6... 

FIGURE 20.4 Regioisomerism in a metathesis polymer prepared from a 5-substituted norbomene derivative (head-tail dyads are structurally identical with tad-head dyads). 

Abstract The addition polymeri2ation of norbomene and its derivatives has been carried out in the presenee of a niekel complex or carboxylate and an electron acceptor to obtain amorphous polymers with bicyclic units. Norbomene copolymers with conjugated dienes or ethylene caimot be obtained with these catalysts because of rapid chain transfer reactions. Norbomene can be copolymerized with ethylene under mild conditions in the presence of nickel phosphoiylide chelates without using any cocatalyst. In most cases, the backbone of the resulting copolymer consists of alternating comonomer units. The new catalysts allow ethylene to be copolymerized with norbomene derivatives containing ester substituents. 

Gringolts ML, Bermeshev MV, Makovetsky KL, Finkelshtein ESh (2009) Effect of substituents on addition polymerization of norbomene derivatives with two Mes Si-groups using Ni(ll)/MAO catalyst. Eur Polym J 45 2142-2149... 

This analysis was made possible because the chemical shifts of the various olefinic carbon double bonds in these unsymmetrically substituted norbomene derivatives are very sensitive to whether they are in an HH, TT or HT/TH unit, as can be seen for the case of poly(l-methylnorbomene) [63] in Figure 1.12. It was therefore possible to examine a range of metathesis catalysts for their ability to produce tactic polymers. In fact, a range of tacticities was observed, with extremes in behaviour being represented by the ReClj catalyst, which produced an all-cis syndiotactic polymer [65] and the W(mesityl) (CO)j catalyst, which produced a high trans isotactic polymer [71]. 

Polymers from norbomene derivatives also offer real promise for industrial development [6, 7]. For instance, poly-5-cyanonorbomene produced with ROMP catalysts is reported to possess high impact and tensile strength, a wide temperature range for useful applications, good creep resistance and transparency, good blending properties, and good workability... 

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]. 

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... 

Covalently attaching the alkylidene to the NHC ensured the proximity of this polymer end to the necessary metal center and enabled the ROMP of COD or dodecatriene to afford cyclic polybutadiene (Figure 20). Later, the same catalyst was also employed with dendritic norbomene derivatives to afford the corresponding cyclic polymer. However, this area still remains challenging and a field for future improvements. 

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