Polynorbornene with 2 catalysts

Wu, Q. Lu Y. Synthesis of a soluble vinyl-type polynorbornene with a half-titanocene/ methylaluminoxane catalyst. J. Polym. Sci., Part A Polym. Chem. 2002, 40, 1421-1425. 

Nickel-based catalysts were introduced for the synthesis of polynorbornenes with a narrow molecular weight distribution and low molecular weights. " ... 

Shiono and coworkers investigated by C-NMR spectroscopy the structure of the P-N copolymer produced with catalyst dimethyl IV-5. They observed several signals for each carbon due to the different comonomer sequences and stereoisomers of the norbornene unit. The signals around 26-30.4 and 30.26-35.42 ppm were tentatively assigned to carbons C5/C6 and C7, respectively. In particular, a broad resonance with several peaks at 31.2-32.1 ppm, which disappeared in the spectrum of polynorbornene, could be assigned to the C7 carbon of the norbornene unit in alternating and/or norbornene diad sequences. The signals at... 

Many of the studies concerning ring-opening metathesis by well-characterized metathesis catalysts have employed substituted norbornenes or norborna-dienes. Substituted norbornenes and norbornadienes are readily available in wide variety, and they usually react irreversibly with an alkylidene. Norbornene itself is the most reactive, and the resulting polynorbornene probably is the most susceptible to secondary metathesis. Formation of polynorbornene often is used as the test reaction for ROMP activity. ROMP by well-defined species has been reviewed relatively recently [30], so only highlights and selected background material will be covered here. 

The catalytic activity for olefin polymerization was evaluated for complex 17a. High molecular weight addition-type polynorbornene (PNB) with a moderate molecular weight distribution (Mw = 106, Mw/Mn = 2.3-3.5) was obtained when 17a was activated with MAO. The activity was highest at 80 °C (107 g of PNB/(mol of Ni) h 1) resulting from an increase in the concentration of active catalyst centers at that temperature. However, further increases in temperature led to catalyst decomposition rather than higher turnover numbers. 

Norbornene and norbornene methyl ester have been polymerized forming a polymer that lacks backbone carbon-carbon double-bond unsaturation. The polymerization catalyst mixture consisted of palladium acetate, a phosphine such as tricyclohex-ylphosphine, a Lewis acid such as dimethyl zinc, and hexafluoroisopropanol. Polynorbornenes prepared in this manner typically had M s> 200,000 daltons with polydispersies less than 2, while poly(norbornene methyl ester) had M s of roughly 100,000 daltons. 

The initial observation of a metal carbene that reacted with an alkene to give a metallacyclobutane complex was reported by Osborn and coworkers for the reaction shown in equation (10). This reaction was observed by NMR spectroscopy at low temperature (—70°C). When this reaction mixture was allowed to warm to higher temperature, polynorbornene was produced in high yield. Shortly after this discovery, the titanocene complex (4) was shown to be an efficient catalyst for the synthesis of monodisperse polynorbornenes. These discoveries, along with the synthesis of a new family of tungsten (5a), molybdenum (5b), and rhenium (6) catalysts,shown in Figure 1, have opened a new era of ROMP chemistry in which the polymer synthesis is guided by the selection of a catalyst... 

The emulsion polymerization of norbornene and cyclooctadiene in water was catalyzed by well-defined, water-soluble Ru-alkylidene metathesis catalysts (such as [RuCl2(TPPTS)2(=CHC02Et)] in the presence of surfactants. Well-controlled polynorbornene latexes were obtained with particle sizes in the range of 50-100 nm (194). The easily available water-soluble allenylidene complex [RuCl2(TPPMS)2(=C=CH—CeHs)] was found catalytically active in the crossmetathesis of methylacrylate with cyclopentene in biphasic mixtures of acidic water and diethyl ether to give C12H19CO2CH3 in 42% yield (195). 

Stereochemical Configuration of Polynorbornene (poly(NB)) and Polynorbor-nadiene (poly(NBD)) Samples Obtained with Conventional ROMP Catalysts... 

Similar to most conventional catalysts, tungsten alkylidene complex 12 (without GaBra) selectively polymerizes the anti isomer of 7-MeNB from a 1 1 mixture of the syn and anti isomers. The resulting poly(fl ti-7-MeNB) contains less than 5% 7-iy -MeNB incorporated. This polymer is atactic and contains 41% trans C=C structures. The hydrogenated polymer (poly-H-(anft-7-MeNB)) is semicrystalline despite its atactic stereochemistry. This is similar to the partial crystallinity of the atactic hydrogenated polynorbornene previously described. The DSC curve for poly-H-(a ti-7-MeNB) displays an endothermic melt transition with a peak maximum at Tm = 176 °C (A// = 26 J/g) (there is an additional minor peak at 137 C). This result shows that partial... 

Monomers with unprotected alkyne groups in the side chain cannot be polymerized without side reactions, as the alkylidene catalyst will engage in a competing alkyne metathesis. This side reaction can be avoided by using monomers with alkyne groups either complexed with di-cobalt octacarbonyl 1 or TMS-protected 2 (Scheme 9.3a,b) [14, 35, 36]. Alkyne incorporation at the chain end was achieved in a post-functionalization approach, reacting hydroxyl-terminated polynorbornene (PNBE) 5 with propargylic acid 6 (Scheme 9.3c) [37]. 

In 2011, Meille, Porri, and co-workers characterized the crystalline form of a vinyl-type polynorbornene (PNB). Fully saturated vinyl polymers or oligomers with a 2,3-exo-disyndiotatic ((is) structure were obtained using an AlEt2Cl-TiCl4 catalyst with a ratio monomer/TiCU of 18 or 250, respectively. A fractionation method was used for the purification. These polymers formed a molecular tube-shape that contained some different types of small molecules like toluene, as shown in Figure 5.23 (red circles). This... 

As of the steric hindrance and the possibility to form allylic intermediates, cyclopentene inserts by metallocene catalysts with a 1,3-structure while polynorbornene shows a 1,2-structure (structure (64)) [544]. 

Nickel-0- and palladium-O-complexes are very active catalysts for the polymerization of norbornene and also for cyclopentene [552-554], Nickel catalysts produce soluble polymers with a molecular weight of over one million while polymers obtained with palladium or metallocene complexes are insoluble. The soluble polymers have an atactic structure. The microstructure of the polynorbornene depends on the catalyst used and is isotactic by synthesis with chiral metallocenes. 

Polynorbornene, the first metathesis polymer produced in industrial scale, was marketed in 1976 by CdF Chimie under the trade name Norsorex . The monomer is produced by Diels Alder reaction of cyclopentadiene and ethylene and polymerized in n-butanol using an RuCls/HCl catalyst. Norsorex is a very high molecular weight (Mn > 2 x 10 g/mol), thermoplast (rg = 35°C) with approximately 90% trans-dovhXe bonds. The polymer is compatible with high loads of extending oils and plasticizers (up to 700%) and easily vulcanizable. By addition of suitable amounts of plasticizers the polymer is converted into an elastomer (Tg = —60 °C). 

Notably, copolymers obtained with various catalysts substantially differed in properties. For example, copolymer of NBSi(OFt)3 with norbornene obtained on [(fl -toluene)Ni(C6F5)2] catalyst, exhibited suitable mechanical properties (a tensile modulus of 1.4 GPa, an elongation-to-break of 15%) while catalyst [(fl -crotyl)Ni(l,4-COD)]PFe gave completely brittle polymers, despite the fact that they had equal molecular weights [231]. Ludovice et al. suggested that these differences could be connected with polymers microstructure a more atactic polymer was brittle, and a more stereoregular one had better mechanical properties [232]. However, determination of microstructure of substituted polynorbornenes is a very intricate... 

Polymers of Norbornenenitriles. On the basis of preliminary evaluation of the properties of various polynorbornenes, the monomer availability and the polymerization behavior, the polymers of the nitrile derivatives were considered most promising as new materials. The homopolymers of 5-norbomene-2-nitrile and 2-methyl-5-norbornene-2-nitrile and a block copolsnner of 5-nor-bornene-2-nitrile with SBR were prepared and evaluated with respect to their physical properties. The ternary system, WCls-paraldehyde-Al(isoBu)3 was used as the catalyst, which efficiently induced the polymerization at a catalyst-to-monomer ratio as low as ca. 4 x lO . ... 

Polymerization of a-norbornenyl-polystyrene macromonomer, a-NBPS, with the Schrock-type catalyst Mo(NAr)(CHtBu)(OC(CH3)(CF3)2)2 in toluene at room temperature gave polynorbornene-polystyrene diblock copolymer (118) in a quantitative yield [86] [Eq. (50)]. 

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