Copolymerization alternating ethylene/propylene

Polyakov, O. G Rappe, A. K. Alternating ethylene/propylene copolymerization RFF molecnlar mechanics force field prognosticates effective zirconocene catalysts. Book of Abstracts, 218th National Meeting of the American Chemical Society, New Orleans, LA, Aug 22-26,1999 American Chemical Society Washington, DC, 1999 INOR-153. Chem. Abstr. 1999,1999, 541786. 

Palladium(II) complexes possessing bidentate ligands are known to efficiently catalyze the copolymerization of olefins with carbon monoxide to form polyketones.594-596 Sulfur dioxide is an attractive monomer for catalytic copolymerizations with olefins since S02, like CO, is known to undergo facile insertion reactions into a variety of transition metal-alkyl bonds. Indeed, Drent has patented alternating copolymerization of ethylene with S02 using various palladium(II) complexes.597 In 1998, Sen and coworkers also reported that [(dppp)PdMe(NCMe)]BF4 was an effective catalyst for the copolymerization of S02 with ethylene, propylene, and cyclopentene.598 There is a report of the insertion reactions of S02 into PdII-methyl bonds and the attempted spectroscopic detection of the copolymerization of ethylene and S02.599... 

Leclerc and Waymouth (119) and, independently, Arndt et al. (120) synthesized alternating copolymers of ethylene and propylene with zirconocene catalysts. The ethylene/propylene (EP) copolymerizations were carried out at 30 and 60°C for each of four metallocene catalysts (Me2C(3-RCp)(Flu)) ZrCl2 (R = H, Me, lsoPr, tertBu) (Fig. 10). As the size of the substituent increased, there were distinct changes in the copolymerization behavior and in the polymer microstructure. 

Toughened polypropylene may be prepared by block copolymerization in which ethylene monomer is added during the final stages of the polymerization of propylene (4). Thus, some polypropylene chains would contain an end block of rubbery ethylene-propylene copolymer. Alternatively, a blend of an elastomeric copolymer of ethylene and propylene (EPR or EPDM) with isotactic polypropylene (PP) can produce an impact-resistant polymer (5). 

Copolymers of ethylene and propylene show, in some cases, elastic properties (324,325). Further incorporation of dienes, such as ethylidenenorbomene or 1,4-hexadiene, produces ethylene-propylene-diene monomer (EPDM) elastomers. Kaminsky (326) and Waymouth (327) have reported the predominantly alternating copolymerization of ethylene and propylene, using Ci and Cg symmetric (cyclopentadienyD(fluorenyl) aasa-zirconocene-based catalysts (eq. 3), demonstrating yet another example of preparation of new materials through rational exploitation of SSC systems. 

An effective understanding of copolymerization chemistry can only be realized through the analysis of the products of the reactions. There have been many accounts of the applications of n.m.r. spectroscopy to polymers and the evaluation of sequence distributions in copolymers figures highly in some of the reviews. " A computer simulation of the C n.m.r. spectrum has been described. Other techniques which have received recent attention are excimer fluorescence spectroscopy for alternating copolymers, mass spectroscopy for ethylene-propylene oxide copolymers, and pyrolysis g.l.c. > A review of analytical techniques has been made by Fujiwara, Mori, Nishioka, and Takeuchi. In a complementary series of articles infi red and Raman spectroscopy have been reviewed by Tanaka C n.m.r. of branched copolyma by Fujiwara and the particular problems of solid and liquid polymer aiuilysis by Tsuge and Mukoyama, respectively. 

Polymers can be made with a single repeating unit these are homopolymers. The repeating unit can be varied to form copolymers. For example, if ethylene is copolymerized with propylene, a copolymer can be formed. Depending on the reaction conditions and the reactivity of the different monomers, copolymers can be alternating, random, or block. This is illustrated with polymers made from monomers X and Y. 

Studies of ethylene-vinyl aromatic monomer polymerizations continue to be published. Chung and Lu reported the synthesis of copolymers of ethylene and P-methylstyrene [28] and the same group extended these studies to produce and characterize elastomeric terpolymers which further include propylene and 1-octene as the additional monomers [29,30]. Returning to the subject of alternative molecular architectures for copolymers, Hou et al. [31] has reported the ability of samarium (II) complexes to copolymerize ethylene and styrene into block copolymers. 

Radiation induced copolymerization of hexafluoroacetone xcith a-olefins has been done over a broad temperature range. From these experiments, it was confirmed that ethylene can be copolymerized below its critical temperature to give an alternating copolymer. A radical mechanism is involved at relatively high temperatures below —10°C, the mechanism has been confirmed to be ionic and may be cationic. Propylene can be copolymerized in a way similar to that of ethylene however, the rate of copolymerization was much slower. Isobutylene did not copolymerize with hexafluoroacetone at 0°C. A 1 2 adduct compound was obtained as the main product. At low temperatures, copolymerization proceeds to some extent. 

Waymouth has recently reported the alternated copolymerization of ethylene and propylene using 39. Preliminary analysis of the polymers using C NMR spectroscopy revealed that the alternated polymers are isotactic. ... 

Carbonylation of some alkenes catalyzed by a cationic Pd complex yields polyketones, which are alternating copolymers. The polyketone 19 of ethylene or propylene named carilon is produced commercially by Shell [10]. A Chain-transfer mechanism for the alternating copolymerization of CO and ethylene was proposed... 

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