Ethylene/CO copolymers

Ethane linkages, 407 Ethene linkages, 407 Ethylene adipates, 212 Ethylene-CO copolymer, 460 Ethylene copolymers, 446 Ethylene glycol (EG), 13, 64. See also EG polyester synthesis depolymerization with, 559 repolymerization of, 561-562 Ethylene oxide (EO) polyols, 211... 

Ethylene carbonate, 10 640, 665 in lithium cells, 3 459 molecular formula, 6 305t physical properties, 6 306t transesterification of, 13 651-652 Ethylene-carbon monoxide (ethylene-CO) copolymers, 5 9 10 197 Ethylene chlorohydrin process, 10 640 Ethylene-chlorotrifluoroethylene (E-CTFE) alternating copolymer (ECTFE), 15 248... 

End-group analysis by C-NMR of the ethylene/CO copolymer produced in methanol genertdly shows the presence of 50 % ester (-COOMe) and 50 % ketone (-COCH2CH3) groups, in accordance with the average overall stmcture of the polymer molecule as depicted in eq. (2). It is not clear a priori which group is the head and which is the tail of the molecules. Moreover, GC and MS analyses of oligomers produced with certain catalysts [13] show, in addition to the expected keto-ester product (Structure 2), the presence of diester (Stmcture 3) and diketone (Stmcture 4) compounds. 

The F NMR signals observed for C Fs appended to an ethylene/CO copolymer are similar however, there is no asymmetry that renders the fluorines inequivalent. See Ref. [58]. 

An alternating ethylene-CO copolymer melts at 257 " C. Incorporation of propylene decreases fhe melting point, enabling processing of the materials (e.g. 6 mol% propene 220°C) [35]. Semicrystalline ethylene/propylene/carbon mon-... 

The introduction of methoxy substituents at the ortho position of the aryl rings of diphosphine-modified cationic palladium catalysts results in markedly increased catalyst performance [49]. With the fully o-OMe-substituted analogue of ligand 1, ethylene-CO copolymers with molecular weights of up to l,2xl0" g mob and narrow polydispersitities ca. 2) were obtained in polymeriza-... 

As previously mentioned, the properties of olefm-CO copolymers depend strongly on the nature of the olefin employed. The glass transition temperature of 1-olefin-CO copolymers decreases from room temperature to nearly -60 °C upon increasing the chain length of the 1-olefin from propylene to 1-dodecene [33]. By contrast to polar ethylene-CO copolymers, copolymers with higher l-olefins display a hydrophobic character. For 1-olefin copolymerization, catalysts with entirely alkyl-substituted diphosphine hgands R2P-(CH2) -PR2 (R=alkyl, by comparison to R=Ph in dppp) such as 3 are particularly well-suited [48]. Efhylene-l-olefin-CO terpolymers and 1-olefin-CO copolymers can be prepared in aqueous polymerizations [43, 47, 48]. In the aforementioned copolymerization reactions, the polyketone was reported to precipitate during the reaction as a sohd [45, 47, 48, 50]. However, in the presence of an emulsifier such as sodium dodecyl sulfate (SDS) and under otherwise suitable conditions, stable polymer latexes can be obtained. 

The newest ethylene/CO copolymers are quite different materials. Shell and others have recently reported success in producing ethylene/carbon monoxide copolymers with up to a 1 1 molar ratio of carbon monoxide to ethylene in their structure. Shell Chemical calls their polymer Carri-lon. A pilot plant was commissioned in Carrington, United Kingdom in 1996. These are high molecular weight polymers in which the carbon monoxide is distributed evenly along the polymer chain. 

Because of the relatively slow rates of radical diffusion in polymer matrices, it seems likely that the probability of secondary recombination will depend very much on the separation achieved while the particles are moving apart with the original excess kinetic energy imparted in the primary dissociation step. This, in turn, should depend on the energy of the exciting photon. There is some evidence for this, even in small molecules in solution. For example, Slivinskas and Guillet (16) report a one-hundied-fold increase in the relative yields of Norrish type I radical products from simple aliphatic ketones, when the reaction is initiated by y-rays rather than ultraviolet light (Table 5). Similar increases were observed in polymeric systems such as in ethylene-CO copolymers (17). 

The catalysts were cationic palladium-phosphine systems prepared from palladium acetate, an excess of triphenylphosphine (PPh3), and a Bronsted acid of a weakly or noncoordinating anion (e.g., p-tosylate (OTs ) methanol was used as both the solvent and a reactant. An unexpected change in selectivity was observed upon replacement of the excess of PPh3 by a stoichiometric amount of the hidentate l,3-bis(diphenylphosphino)propane (dppp). Under the same conditions, these modified catalysts led to perfectly alternating ethylene/CO copolymers with essentially 100% selectivity [Eq. (2)] [12-14]. 

Use of this tandem method resulted in a model ethylene/CO copolymer (Figure 2, polymer 2) that had a Tm (134 °C) close to that observed in our linear ADMET polyethylene (Figure 4, second entry) [17]. Since carbonyl and methylene groups have similar space filling characteristics, the CO functional group may be expected to cause very little disruption of the lamellar crystal lattice of polyethylene. 

Watson, M.D. and Wagener, K.B. (2000) Tandem homogeneous metathesis/heterogeneous hydrogenation Preparing model ethylene/C02 and ethylene/CO copolymers. Macromolecules 33,3196-3201. 

In this chapter, the transition-metal-catalyzed synthesis of completely alternating ethylene/CO copolymer will be reviewed in relation to the catalyst design and reaction mechanisms. Next, synthesis of nonaltemating copolymers will be discussed. Reactions of mono-substituted ethylene with CO will be discussed together with the stereochemistry of the products and finally applicable functional olefins will be described. 

The physical properties of the nonaltemating ethylene/CO copolymers have been investigated. The melting points of ethylene/CO nonaltemating copolymers were much lower than those of perfectly alternating copolymers (Tm 260°C) and decreased with increasing multiple ethylene units. For example, copolymers with CO contents of 35 and 10% exhibited melting temperatures of 220 and 118 °C, respectively. This tendency could be attributed to the relatively weakened interactions between the polymer chains. 

One of the unique features of the alkene/CO copolymer is the existence of multiple carbonyl groups in the main chain. Thus, versatile chemical transformations of the carbonyl groups were examined to provide new polymers (Scheme 16). The 1,4-diketone structure ethylene/CO copolymers can be transformed into pyrroles, thiophenes, and furans upon treatment with primary amines,phosphorus pentasulfide, and phosphorus pentoxide, respectively. ... 

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