Copolymerization ethylene/norbomene

Ethylene—Propylene Rubber. Ethylene and propjiene copolymerize to produce a wide range of elastomeric and thermoplastic products. Often a third monomer such dicyclopentadiene, hexadiene, or ethylene norbomene is incorporated at 2—12% into the polymer backbone and leads to the designation ethylene—propylene—diene monomer (EPDM) mbber (see Elastomers, synthetic-ethylene-propylene-diene rubber). The third monomer introduces sites of unsaturation that allow vulcanization by conventional sulfur cures. At high levels of third monomer it is possible to achieve cure rates that are equivalent to conventional mbbers such as SBR and PBD. Ethylene—propylene mbber (EPR) requires peroxide vulcanization. 

The resulting complexes can be effectively employed as single component catalysts to homopolymerize ethylene or copolymerize ethylene with acrylates [50, 51] and a variety of other polar monomers including vinyl ethers, [51,52] vinyl fluoride [53], iV-vinyl-2-pyrrolidinone, and AMsopropylacrylamide [54], In fact, the resulting catalysts are so robust that they can be used as single component catalysts in aqueous emulsion homo-polymerization of ethylene and copolymerization of ethylene with norbomenes and acylates [55]. 

These requirements have met using a mixed catalystic system consisting of an iron catalyst complex that can oligomerize ethylene and a zirconium transition metal complex that can copolymerize ethylene and the nonconjugated monomer 5-ethylidene-2-norbomene. Using this catalytic pair nonbrancy poly(ethylene-co5-ethylidene-2-norbomene) and poly (ethylene-col,4-hexadiene) were prepared. 

W. Wang and K. Nomura, Remarkable effects of aluminum cocatalyst and comonomer in ethylene copolymerizations catalyzed by (arylim-ido)(aryloxo) vanadium complexes efficient synthesis of high molecular weight ethylene/norbomene copolymer, Macromolecules, 38(14) 5905-5913, July 2005. 

In the course of our polymerization studies the performance of these new catalysts in the copolymerization of norbomenes with a-olefms such as ethylene, 1-hexene and 1-decene was investigated. The primary reason for exploring this area was to enable copolymerization of norbomenes with ethylene (and other a-olefins)... 

A chain migratory insertion mechanism for ethylene/norbomene copolymerization utilizing both A and B coordination sites in an alternating fashion is implied by the derived parameter set... 

FIGURE 16.12 Palladium a-diimine catalysts used for ethylene/norbomene copolymerization (GLY = 1,2-ethanediimine = glycine-derivate BUD = 2,3-butanedirmine). 

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. 

Table 1. Copolymerization of norbomene (NB) and ethylene in the presence of complex II...

Kaminsky W, Amdt-Rosenau M (2000) Homo- and copolymerization of cycloolefins by metallocene catalysts. In Scheirs J, Kaminsky W (eds) Metallocene-based polyolefins, vol 2. Wiley, Chichester, p 89 and references there in Kaminsky W, Beulich I, Arndt M (2001) Macromol Symp 173 211 Tritto I, Boggioni L, Sacchi MC, Locatelli P, Ferro DR, Provasoli A (1999) Copolymo-microstructures of ethylene norbomene copol5tmers prepared with homogeneous metallocene based catalysts. In Kaminsky W (ed) Metalorganic catalysts for synthesis and polymerization. Springer, Berlin, p 493... 

In addition to linear a-olefins, Shino and coworkers reported that 5/MAO catalyzed the living copolymerization of ethylene and norbornene. At 0 °C, 5/MAO can furnish poly(E-co-NB) with 53 mol% norbornene and M = 18 000 g/mol with MJM =1.16 (Hasan et al, 2004b). In addition, a linear increase in with reaction time was observed for this system. At 40 °C, a similar compound, lO/MAO, also provided ethylene-norbomene copolymers with fairly narrow PDls MJM =. 2 -. 21) (Hasan et al, 2004a). 

To enhance the living nature of the system, Li and coworkers explored the copolymerization of norbomene and ethylene. They found that the copolymerization of ethylene and norbomene by 52g/MAO resulted in polymers with narrow molecular-weight distributions (M /Mn < 1.2)... 

Bhriain et al. daim that GGTP occurs in ethylene-norbomene copolymerizations using metallocene 23 in combination with zinc or aluminum alkyls. The reversibility is indicated by a reduction in M and a modest narrowing of the distribution (1.6reversible chain transfer in ethylene polymerization using the hafiiium amidinate precatalyst 24 with DEZ, produdng mono-disperse PEs with Mn s up to 665 g mol". ... 

Figure 8 Zirconocene precatalysts for living ethylene/norbomene copolymerization.

Research Focus Ambient temperature copolymerization of ethylene with 5-norbomen-2-yl acetate or with ethylene and 5-norbomen-2-yl alcohol. 

Ethylene and 5-norbomen-2-yl-acetate were also copolymerized using N-(2,6-diisopropylphenyl)-2-(2,6-diisopropylphenylimino)propanamide-benzyltrimethyl-phosphine nickel. 

Norbomen-2-yl 4-(l-(3-(2,2,5-trimethyl-4-phenyl-3-azahexoxy))ethyl)ben-zyl ether, (V), was previously prepared by the authors (4) and used in the controlled free radical copolymerization of ethylene and 5-norbomen-2-ol. Polymerization were carried out in the presence of the two component catalyst mixture of the current application. 

With larger amount of propylene a random copolymer known as ethylene-propylene-monomer (EPM) copolymer is formed, which is a useful elastomer with easy processability and improved optical properties.208,449 Copolymerization of ethylene and propylene with a nonconjugated diene [EPDM or ethylene-propylene-diene-monomer copolymer] introduces unsaturation into the polymer structure, allowing the further improvement of physical properties by crosslinking (sulfur vulcanization) 443,450 Only three dienes are employed commercially in EPDM manufacture dicyclopentadiene, 1,4-hexadiene, and the most extensively used 5-ethylidene-2-norbomene. 

Another important use of BC13 is as a Friedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cydophosphazenes to polymers (81,82) polymerization of olefins such as ethylene (75,83—88) graft polymerization of vinyl chloride and isobutylene (89) stereospecific polymerization of propylene (90) copolymerization of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerization of norbomene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Homogeneous vanadium-based catalysts formed by the reaction of vanadium compounds and reducing agents such as organoaluminum compounds [10-12] are used industrially for the production of elastomers by ethylene/propene copolymerization (EP rubber) and ethylene/propene/diene terpolymerization (EPDM rubber). The dienes are usually derivatives of cyclopentadiene such as ethylidene norbomene or dicyclopentadiene. Examples of catalysts are Structures 1-4. Third components such as anisole or halocarbons are used to prevent a decrease in catalyst activity with time which is observed in the simple systems. 

In 1998, Grubbs and co-workers [83, 84] reported on a new type of neutral Ni(II) complexes with salicylaldimin ligands (32). With these catalysts low-branched polyethylenes were obtained with a narrow molecular weight distribution. The copolymerization of ethylene and norbomene is possible. Fe and Co catalysts were used for the linear polymerization of ethylene by Gibson [85] and Brookhart [86] independently (33). Activities of 10 TONs were reported. The polyethylenes obtained are highly crystalline with a broad molecular weight distribution. 

Since the aforementioned investigations, significant advances in aqueous catalytic insertion polymerization have only been made over the past decade. Alternating copolymerization of olefins with carbon monoxide, polymerization of ethylene and 1-olefins, and polymerizations of norbomenes and of butadiene have been studied. 

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