Homopolymerization, of norbornene

Thus, until the last decade, three families of catalysts have been reported to catalyze the addition, or vinyl-type homopolymerization of norbornene resulting in poly(2,3-bicyclo[2.2.1]hept-2-ene). These three catalyst types are the classical TiC -based Ziegler systems (type 1), the zirconocene/aluminoxane systems (type 2) and certain electrophilic palladium(II) complexes (type 3). 

The homopolymerization of norbornene is described in a process patent to Idemitsu Kosan [29]. This patent application describes the use of catalysts compris-... 

A series of homopolymerizations of norbornene and copolymerizations of norbornene and 5-decyhiorbornene were carried out at a 4000 1 monomer to catalyst ratio using catalyst 1. The polymerizations were conducted at room temperature for 1 h before short stopping the reaction. The results of these runs are presented in Tab. 4.1. 

Mechanisms involving rearrangements in the norbornene moiety to yield products with 2,7 linkages, analogous to the rearrangement noted in the homopolymerization of norbornene, have been proposed previously. However, there is as yet no direct evidence... 

It has previously been proposed that the saturated products from the homopolymerization of norbornene (17) and the CPD-MAH Diels-Alder adduct (12-15), and probably from the furan-maleic anhydride Diels-Alder adduct (11), have rearranged structures. An analogous structure would arise from the homopolymerization of the cyclopentadiene-N-phenylmaleimide CPD-NPMI adduct, as follows ... 

Metallocene/methylaluminoxane (MAO) and other single site catalysts for olefin polymerization have opened a new field of synlhesis in polymer chemistry. Strained cyclic olefins such as cyclobutene, cyclopentene, norbornene (NB), and their substituted compounds can be used as monomers and comonomers in a wide variety of polymers." Much interest is focused on norbornene homo- and copolymers because of the easy availability of norbornene and the special properties of their polymers. Norbornene can be polymerized by ring opening metathesis polymerization (ROMP), giving elastomeric materials, or by double bond opening (addition polymerization). Homopolymerization of norbornene by double bond opening can be achieved by early and late transition metal catalysts, namely Ti, Zr, Hf, Ni, - ° and Pd (Scheme 16.1). 

The use of early transition metal catalysts for the homopolymerization of norbornene dates back to 1963. Sartori et al. reported on the polymerization of norbornene by TiCl4/(/-Bu)3Al (Ti Al=l 2). Further reports refer to the analogous TiCl4/Et3Al system, which produces a mixture of ROMP and addition polymer. ... 

While the copolymerization of norbornene and ethylene by vanadium and titanium catalysts had been investigated in the 1970s, it was not until the invention of metallocene/MAO catalysts and their application to the homopolymerization of norbornene and other cycloolefins by Kaminsky et ai.8,15,19 that the use of early transition metal catalysts for the addition polymerization of norbornene drew new attention. Nevertheless, the industrial relevance of E/NB copolymers, and the nature of the homopolymers, described in the first reports as insoluble in organic solvents, crystalline, and extremely high melting, focused further investigations on copolymers rather than on norbornene homopolymers. 

Thus, it was not until 1990 that the group of Kaminsky and Arndt-Rosenau took a more detailed look at the homopolymerization of norbornene and the structures of the resulting polymers. Driven by the growing interest in copolymers with high norbornene contents and high glass transition (Tg) temperatures, as well as the unusual properties of PNBs, Arndt-Rosenau et al. used the hydrooligomerization technique to produce saturated model norbornene dimers and trimers with metallocene catalysts known to produce atactic, isotactic, and syndiotactic poly(a-olefins) (1-3, Table 16.1). 

Single site catalysts, such as metallocene compounds, CGCs, and nickel or palladium diimine complexes, used in combination with MAO or borate cocatalysts, are highly active for the homopolymerization of norbornene and its copolymerization with ethylene. The structure of the norbornene homo- and copolymers can be widely influenced by the symmetry and structure of the ligands on the transition metal complexes. 

The homopolymerization of norbornene using early transition metal catalysts drew new attention with the discovery of metallocene/MAO catalysts. " It was found that most of the obtained polymers are insoluble in organic solvents, are crystalline, and show extremely high melting temperatures. Information about the microstructure was gathered by Arndt et who used the hydrooligomerization technique to... 

The polymerization activity of the homopolymerization of norbornene is low because of the steric hindrance of zirconocene catalysts. Activities of 150 kg polynorbornene (mol Zr)" h" were reached using rac-[Et(Ind)2]ZrCl2 at 20... 

Half-sandwich complexes of titanium, when activated by a cocatalyst such as MAO, are even more active for the homopolymerization of norbornene than metallocenes.Peucker and Heitz found that chromium-based half-sandwich complexes can also be activated to produce polynorbornenes and E-N copolymers. 

Organolanthanide complexes can catalyze not only the homopolymerization of ethylene, but also the copolymerization of ethylene with some nonpolar and polar monomers [139, 140], A series of neutral, anionic, and cationic organolanthanide complexes catalyze the copolymerization of ethylene with styrene, a-olefins, methylenecyclopropane, norbornene,... 

Similarly to the zirconocene/MAO catalysts, the activity of the Idemitsu catalyst systems is poor when the whole catalyst system (catalyst-i-co-catalyst) is taken into account. In the very best example (in terms of catalyst activity and polymer yield) nickel bis (acetylacetonate) was used in combination with MAO (molar ratio 1 200) to homopolymerize norbornene in toluene at 50 °C for 4 h affording a 70% conversion into high molecular weight (M 2.2x10 ), toluene-soluble poly-(norbornene). The ratio of norbornene to nickel was 20000 1 and the ratio of norbornene to aluminum was only 100 1. Thus, while the yield of polymer is high based on the nickel catalyst (25 700 g per g nickel), the yield based on aluminum is very poor (260 g per g aluminum or about 120 g per g MAO). It can readily be estimated that the cost of the MAO activator alone would add significantly to the cost of the polymer, as well as requiring costly removal of catalyst residues from the polymer. 

The mechanism of the crosslinking reaction has been postulated as (a) dissociation of the terminal cyclopentadiene-N-arylma1-eimide Diels-Alder adduct to the monomeric precursors, which immediately react to form an adduct which initiates the homopolymerization of the undissociated terminal norbornene rings to form a saturated polymer (j>). 

The homopolymerization of the endo and exo adducts was carried out in the melt at 150 to 260 C and in chlorobenzene at 120°C (Table I). Polymer was obtained when the catalyst was used at a temperature where the half-life was short, e.g. less than 2 hr, conditions shown to be effective in the homopolymerization of maleic anhydride (16), norbornene (17, 18) and 5-norbornene-2,3-di-carboxylic anhydride (CPD-MAH adduct) (12-15), as well as the... 

Polymacromonomers of polystyrene (PS), poly(ethylene oxide) (PEO) and polybutadiene (PB) could be prepared [1,8] by ROM homopolymerization of various norbornene-terminated macromonomers. Complete conversions were achieved,... 

Ethene-norbornene copolymers are most interesting for technical applications as they can be made from easily available monomers and provide glass transition temperatures up to 200 °C. Table 11 presents the activities and comonomer ratios for the several applied catalysts of C2- and Cj-symmetry. Cs-symmetric zirconocenes are more active in the copolymerization than for the homopolymerization of ethene. Under the chosen conditions, [En(Ind)2]ZrCl2 develops the highest activity while the highest comonomer incorporation is achieved by [Ph2C(Ind)(Cp)]ZrCl2. 

Myagmarsuren G, Lee Ki-Soo, Jeong O-Yong, Ihm Son-Ki (2005) Homopolymerization of 5-alkyl-2-norbornenes and their copolymerization with norbomene over novel Pd(acac)2/PPh3/Bp30Et2 catalyst system. Polymer 46 3685-3692... 

Esters of endomethylene tetrahydrophthalic anhydride and other derivatives of norbornene are known to form eutectic mixtures with Ma/ 2.73.340,341,374-379) SQij j.gtate copolymerizatiou of the eutectic mixture of monopropyl endomethylene tetrahydrophthalate and MA, using Co y-ray initiation, produces nonequimolar copolymer. " Neither monomer homopolymerizes under the experimental conditions used. It is believed that copolymerization of the monomer mixture is made possible by the increased... 

ButG5H3, G9H6) have been synthesized either by the standard salt metathesis or the amine elimination procedure. These compounds are used as pre-catalysts for norbornene homopolymerization and ethylene-norbornene co-poly-merization. The influence of the catalyst symmetry and structure on the activity, norbornene incorporation, and polymer and co-polymer microstructure has been studied.706... 

Since the F-MAH and CPD-MAH Diels-Alder adducts yield unsaturated and saturated polymers, respectively, as a result of radical catalyzed homopolymerization at elevated temperatures, it was of interest to investigate the radical catalyzed polymerization of the isomeric exo- and endo-cyclopentadiene-N-phenylmaleimide adducts, models for the norbornene end-capped polyimides whose thermal polymerization products have structures which have been diversely depicted as saturated and unsaturated, without experimental verification. 

In the case of the studied bis-MesSi-norbornenes, one of the substituents is always in the disadvantageous encio-conformation. Probably this is the reason for their inactivity in AP. But when the mixture of different conformers is used, a part of the enr/o-form could participate in copolymerization with the exo-form. This fact excludes the possibility of homopolymerization for these monomers but does not exclude the proceeding of their copolymerization with norbornene itself nor with its substituted exo-derivatives. 

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