Carbon monoxide comonomer

The same group of coordination polymerisations in which alkene undergoes re complex formation with the metal atom includes the copolymerisation of ethylene, a-olefins, cycloolefins and styrene with carbon monoxide in the presence of transition metal-based catalysts [54-58], In this case, however, the carbon monoxide comonomer is complexed with the transition metal via the carbon atom. Coordination bond formation involves the overlapping of the carbon monoxide weakly antibonding and localised mostly at the carbon atom a orbital (electron pair at the carbon atom) with the unoccupied hybridised metal orbitals and the overlapping of the filled metal dz orbitals with the carbon monoxide re -antibonding orbital (re-donor re bond) [59], The carbon monoxide coordination with the transition metal is shown in Figure 2.2. 

Polymerization of ethylene and carbon monoxide comonomers to produce a perfectly alternating carbon monoxide/ ethylene copolymer Seml-crystalllne 1.22... 

It has been shown by Barb and by Dainton and Ivin that a 1 1 complex formed from the unsaturated monomer (n-butene or styrene) and sulfur dioxide, and not the latter alone, figures as the comonomer reactant in vinyl monomer-sulfur dioxide polymerizations. Thus the copolymer composition may be interpreted by assuming that this complex copolymerizes with the olefin, or unsaturated monomer. The copolymerization of ethylene and carbon monoxide may similarly involve a 1 1 complex (Barb, 1953). 

Methyl methacrylate (MMA), 16 227 Alfrey-Price parameters, 7 617t azeotropic mixtures with, 16 236t block copolymer synthesis, 7 647t C-2 routes to, 16 252-254 C-3 routes to, 16 246—252 C-4 routes to, 16 254—257 carbon monoxide in production of, 5 6 chain-transfer constants for, 16 284t comonomer with acrylonitrile, 1 451t cumene as feedstock, 8 156 in flame-retardant resin formulation,... 

In addition to a-olefins, p-/-butylstyrene can be used as a comonomer for the isotactic specific copolymerization with carbon monoxide with chiral induction [32], Whereas bipyridyl as ligand gives a syndiotactic polymer, the Pd-catalyzed polymerization with ligand 11 leads to a polymer with isotacticity of over 98% and high optical activity ([ ]D -536° (in CH2C12)) [33, 34]. The BINAPHOS catalyst described above is also effective in this type of copolymerization [25],... 

Active sites present in palladium-based catalysts, which promote the alternating insertion of coordinating comonomers, ethylene to the acyl Pd-C(O) bond and carbon monoxide to the alkyl Pd-CH2 bond, appear to be cationic Pd(II) species with a square planar, formally d° 8-electron structure, [L2(M)Pd(II)—P ]+, accompanied with weakly coordinating counter-anions [478 180,484],... 

Use of statistical copolymers in blends is usually predicated on the existence of a specific interaction between one of the comonomers in the copolymer and other ingredients in the mixture. Thus PVC is miscible with the ethyicne/ethyl acrylate/carbon monoxide copolymers [28]. The homogenizing effect here is a weak acid-base interaction between the carbonyl of the copolymer and the weakly... 

Late transition-metal complexes can also polymerize nonpolar and polar comonomers, such as alkyl acrylates, acrylonitrile, or carbon monoxide. Polyketones have been efficiently produced through CO-ethylene copolymerizations [46],... 

Recently, Ni- and Pd-based catalysts have been developed in order to copolymerize nonpolar ethylene, 1-olefins or cycloolefins with polar comonomers, such as carbon monoxide and methyl acrylate or 1-olefins, containing polar groups which are separated by at least two methylene... 

The practically most important copolymer is made from ethene and propene. Titanium- and vanadium-based catalysts have been used to synthesize copolymers that have a prevailingly random, block, or alternating structure. Only with Ziegler or single site catalyst, longer-chain a-olefins can be used as comonomer (e.g., propene, 1-butene, 1-hexene, 1-octene). In contrast to this, by radical high-pressure polymerization it is also possible to incorporate functional monomers (e.g., carbon monoxide, vinyl acetate). The polymerization could be carried out in solution, slurry, or gas phase. It is generally accepted [173] that the best way to compare monomer reactivities in a particular polymerization reaction is by comparison of their reactivity ratios in copolymerization reactions. 

At elevated temperatures, ethene can be copolymerized with a number of unsaturated compounds by radical polymerization [174-180] (Table 7). The commercially most important comonomers are vinyl acetate [181], acrylic acid, and methacrylic acid as well as their esters. Next to these carbon monoxide is employed as a comonomer, as it promotes the polymer s degradability in the presence of light [182]. 

The introduction of metallocene and other single-site technologies (Fig. 31) made possible new process/ comonomer combinations, use of novel comonomers such as styrene, norbornene, and carbon monoxide, and seemingly impossible property combinations. Potential adaptation of polyolefin manufacturing technologies to the production of engineering thermoplastics is possible. 

In order to achieve higher-performing engineering thermoplastic properties, significant modification of the polymer backbone is required. The use of carbon monoxide as a comonomer has been of interest based on its abundance and its ability to confer functionahty. However, conventional early transition metal polyolefin catalysts are ineffective at copolymerizing olefins with carbon monoxide. 

The Strictly Alternating Copolymerization of Carbon Monoxide and a-Olefin Comonomers 808... 

In copolymerization experiments with polar comonomers (e.g., carbon monoxide or MA), an interesting phenomenon can be observed. This is the so-called Tjackbiting mechanism, where the growing poljuner chain tilts back and the metal is stabilized by a chelating coordination (usually five- or six-membered ring) of a functional group on the polymer chain. Details for this reaaion will be explained further in Section 3.24.4.1.2(ii) (Figure 6). 

The copolymerization of carbon monoxide and a-olefins (mainly ethene and propene Scheme 20) is the prominent example for an olefm/polar comonomer copolymerization system suitable for industrial application. This process was employed by Shell and BP in industrial pilot plants, but the resulting copolymers could unfortunately not be commercially established in the market. The successful implementation in an industrial process was the result of a combination of high catalyst activities and inexpensive monomers as well as the facile control of the reaction and the product properties. 

Absent from Table 10 are the comonomers carbon monoxide, carbon dioxide, and sulfur dioxide. These comonomers are not included because their copol mieiization does not obey the normal copolymer model illustrated by reactions (vix—xvii) and hence cannot be described by kinetic parameters which take into account only these reactions. For example. Furrow (/28) has i own that caibon dioxide will react with growing polyethylene chains in a free-radical reaction, but that it terminates the chains giving carboxylic acids. It does not copolymerize in the usual sense (which would give polyesters). Carbon monoxide and sulfur dioxide appear not to obey the normal cppol3nner curve of feed composition versus polymer composition and it has been reported that these materials form a complex with ethylene whidi is more reactive than free CO or SOg, perhaps a 1 1 complex. Copolymerization of both CO and SO is further complicated by a ceiling temperature effect. Cppolymerization has been carried out with ethylene and these monomers, however, and poly-ketones and pol3Tsufones are the resultant products. 

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