Synthesis and characterization of syndiotactic 3,4-polyisoprene prepared with diethylbis(2,2′-bipyridine)iron–MAO

Bazzini, Cristina; Giarrusso, Antonino; Porri, L.; Pirozzi, Beniamino; Napolitano, Roberto

doi:10.1016/j.polymer.2004.02.042

Cited by 67 publications

(46 citation statements)

References 16 publications

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“…[16] The syntheses of the four polymers have been reported in the literature and their crystal structures have been determined or partially characterized. [2,10,11,13,25,26] However, for each polymer, only one crystalline modification with the value of the chain axis typical of highly extended conformations has been evidenced until now.…”

Section: Resultsmentioning

confidence: 99%

“…[1,2] The use of new catalytic systems based on transition metal complexes and organoaluminium compounds, and the choice of suitable conditions of polymerization, have allowed more recently the synthesis of vinyl polymers of 1,3-dienes with a high degree of stereoregularity, sufficient to obtain semicrystalline polymers. [3][4][5][6][7][8][9][10][11] The crystal structures of some of these polymers have been also reported. [12,13] The structural characterization of polymers can be approached by molecular mechanics studies.…”

Section: Introductionmentioning

confidence: 99%

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Chain Conformations in the Crystalline Field of Syndiotactic Vinyl Polymers Deriving from 1,3‐Diene Monomers. Analysis by Molecular Mechanics

Pirozzi¹,

Napolitano

Esposito

2004

Macro Theory & Simulations

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Conformational energy calculations on the chain conformation in the crystalline field have been performed for various syndiotactic vinyl polymers deriving from 1,3-diene monomers. Energy maps as a function of the independent torsion angles have evidenced for all the polymers minima corresponding to highly extended and to helical chains. Energy minimizations as a function of all the internal parameters for the s(2/1)2 and tcm symmetries have allowed the evaluation of the energy differences between chains having the two symmetries and the prediction of the values of the conformational parameters for each polymer. The results have been compared with the experimental data reported in the literature for some of the studied polymers

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chain Conformations in the Crystalline Field of Syndiotactic Vinyl Polymers Deriving from 1,3‐Diene Monomers. Analysis by Molecular Mechanics

Pirozzi¹,

Napolitano

Esposito

2004

Macro Theory & Simulations

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“…9,10 For high-value applications where colour, odour or protein content of natural rubber may be an issue, such as in surgical gloves, anionically polymerized isoprene has been used, though low temperatures are required to keep cis-1,4 selectivity high with the organolithium initiators used. 66 More recently, replacement of one pyridyl group with a bulky imine has presented intriguing results. 13,64 However, there is a long-term problem with use of lanthanides for this purpose.…”

Section: Catalyst Performance Comparisonmentioning

confidence: 99%

The behaviour of β-triketimine cobalt complexes in the polymerization of isoprene

Alnajrani

Mair

2015

RSC Adv.

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Four new b-triketimine cobalt complexes [(LCo-m-Br) 2 ][BArF] 2 where L ¼ N,N 0 ,N 00 -triaryl-b-diketimine were synthesised and then characterized by single-crystal X-ray diffraction, MALDI-MS and elemental analysis. In combination with three previously reported, they provided a series of seven subtly different complexes which were screened for activity in the catalysis of isoprene polymerization: the structure of the ligand (L) had strong effects on activity and stereoselectivity. The produced polyisoprene contained a mixture of cis-1,4, trans-1,4 and 3,4-enchained monomers; 4,1-errors followed 3,4 errors. The highest percentage of cis-1,4 content (80%) was obtained with complex 5 where two electron-withdrawing fluorine substituents occupied the 2-and 6-positions of two of the imino-aryl rings. This polymer was obtained in 98.5%conversion. Both cis-1,4 content and activity decreased when electron donor substituents were present on the aryl rings, so that complex 1, with three methyl substituents in positions 2, 4 and 6 gave the lowest cis-1,4 content (73.6%), with a conversion of only 58.5%, under identical conditions. The temperature of the polymerization, the type of aluminium co-catalyst used, and the Al/Co ratio strongly affected the activity and microstructure of the polyisoprene produced. Ethylaluminiumsesquichloride was the most active of a range of organoaluminiums screened. A kinetic study using complex 6 as catalyst demonstrated that the polymerization was first-order in monomer, and that approximately 12% of cobalt formed active centers. The combination of high molecular weight (>10 5 ) with moderately high activity at conveniently accessible temperatures to give predominantly cis-1,4-polyisoprene but with 3,4 units to promote efficient crosslinking is potentially attractive, and has not previously been attained with 3d elements.

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“…The 3,4‐PI, which showed good potential for preparing long‐life ‘green’ tires such as those with wet‐skid resistance and low‐rolling resistance, was synthesized with catalyst systems including patented organolithium and ferric acetylacetate, transition metal complexes such as AlEt 3 –Ti(OR) 4 , (1,2‐bis(dimethylphosphino)ethane) 2 CrCl 2 –MAO, ferric complexes chelated by nitrogen ligands and the rare earth metal catalyst system . Similar to the synthesis of 1,2‐PBd, no reports involving the synthesis of PI with a high 3,4 content with supported Z‐N catalysts have been published allowing for complex catalyst systems and different active species absorbed on the supports.…”

Section: Stereospecific Polymerization Of Isoprenementioning

confidence: 99%

Stereospecific polymerization of olefins with supported Ziegler − Natta catalysts

Jiang

2013

Polymer International

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Synthesis and characterization of syndiotactic 3,4-polyisoprene prepared with diethylbis(2,2′-bipyridine)iron–MAO

Cited by 67 publications

References 16 publications

Chain Conformations in the Crystalline Field of Syndiotactic Vinyl Polymers Deriving from 1,3‐Diene Monomers. Analysis by Molecular Mechanics

Chain Conformations in the Crystalline Field of Syndiotactic Vinyl Polymers Deriving from 1,3‐Diene Monomers. Analysis by Molecular Mechanics

The behaviour of β-triketimine cobalt complexes in the polymerization of isoprene

Stereospecific polymerization of olefins with supported Ziegler − Natta catalysts

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