A <i>C</i><sub>2</sub>-Symmetric, Living α-Diimine Ni(II) Catalyst:  Regioblock Copolymers from Propylene

Cherian, Anna E.; Rose, Jeffrey M.; Lobkovsky, Emil; Coates, Geoffrey W.

doi:10.1021/ja0540021

Cited by 213 publications

(125 citation statements)

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“…When the polymerization temperature is Ϫ60°C or lower, iPP results, whereas at room temperature, the incorporation of trimethylene units [O(CH 2 ) 3 O] predominates. These unbranched units are due to 3,1-insertions arising from catalyst chain-walking (18). The rPP block that results at 0°C resembles PEP (nominal F e ϭ 0.53) more than it does PP and in fact has a glass transition temperature (less than Ϫ40°C) that is much lower than conventional amorphous PP.…”

Section: Resultsmentioning

confidence: 97%

“…Complexes 1 and 2 were synthesized as previously reported (12,18). Synthesis of sPP-b-PEP-b-sPP (synTB).…”

Section: Methodsmentioning

confidence: 99%

“…Notably, Sita (17) has recently reported the synthesis of elastomeric multiblock polymers with atactic PP and iPP segments. Coates (18) has recently reported a chiral nickel alpha-diimine catalyst that produces di-and elastomeric triblock polypropylenes with isotactic and regioirregular (rPP) PP blocks, controlled by the polymerization temperature. A possible advantage of this system is that rPP blocks are virtually indistinguishable from PEP blocks and have a suitably low T g of approximately Ϫ55°C, enabling the synthesis of thermoplastic elastomers from a single monomer.…”

Section: Block Polyolefinsmentioning

confidence: 99%

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Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Hotta

Cochran

Ruokolainen

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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125

116

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We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene-blockpoly(ethylene-co-propylene)-block-syndiotactic polypropylene and isotactic polypropylene-block-regioirregular polypropyleneblock-isotactic polypropylene triblock copolymers were synthesized. The volume fraction and composition of the blocks, as well as the overall size of the macromolecules, were controlled by sequential synthesis of each block of the polymers. These triblock copolymers, with semicrystalline end-blocks and mid-segments with low glass-transition temperatures, show significant potential as thermoplastic elastomers. They have low Young's moduli, large strains at break, and better than 90% elastic recovery at strains of 100% or less. An isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene pentablock copolymer was synthesized that also shows exceptional elastomeric properties. Notably, microphase separation is not necessary in the semicrystalline isotactic polypropylenes to achieve good mechanical performance, unlike commercial styrenic thermoplastic elastomers.block copolymer ͉ polypropylene T he applications of a polymer are largely determined by its chemical, physical, and mechanical properties. These properties are in turn determined by polymer morphology, which is dictated by polymer structure and composition. Thermoplastic elastomers are a classic example where polymer architecture engenders unique properties. Block copolymers that contain at least two blocks that are hard at room temperature, separated by blocks with a glass transition temperature (T g ) below room temperature, typically exhibit elastomeric properties if the low T g block volume is large (1-5). The most well known elastomers of this type are the polystyrene (PS)-block (b)-polybutadiene-b-PS triblock copolymers, sold commercially by Kraton Polymers. Such materials normally possess a microphase-separated morphology in which 10-nm-scale domains of the hard blocks (e.g., PS) are embedded as spheres or cylinders within a continuous phase of the low T g soft blocks. The hard domains serve as thermally reversible crosslinks that at room temperature produce high levels of recoverable elasticity in the soft phase.Sequence control of a synthetic polymer is most easily accomplished by using a synthetic technique that allows the sequential addition of one or more monomers to the macromolecule in a chain growth process without spontaneous termination. These techniques are collectively called living polymerizations, and despite many successes over the last half century, their further development remains one of the most important frontiers in polymer science. In the case of the Kraton triblock copolymers, a living anionic polymerization process is used to synthesize the materials. Because approximately t...

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Section: Resultsmentioning

confidence: 97%

“…Complexes 1 and 2 were synthesized as previously reported (12,18). Synthesis of sPP-b-PEP-b-sPP (synTB).…”

Section: Methodsmentioning

confidence: 99%

Section: Block Polyolefinsmentioning

confidence: 99%

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Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Hotta

Cochran

Ruokolainen

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

125

116

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“…10 Commercially available trans-2-butene monomer was purchased from Wako Pure Chemical and used without purification. MMAO diluted with toluene (2.53 mol/L) (Tosoh-Fine Chem.…”

Section: Methodsmentioning

confidence: 99%

Polymerization of trans-2-Butene with (α-Diimine)Ni(II) Complex in Combination with Et2AlCl

Endo

Kondo

2006

Polym J

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ABSTRACT:Polymerization of trans-2-butene with (-diimine)Ni(II) complex in combination with R 3 Al (R ¼ CH 3 , C 2 H 5 , i-C 4 H 9 ), Et 2 AlCl, EtAlCl 2 and methylaluminoxane (MAO) was investigated. Et 2 AlCl and EtAlCl 2 as well as MAO were found to be an effective cocatalyst for the polymerization of trans-2-butene to give a high molecular weight of the polymer in good yields, but R 3 Al did not give any polymers. In contrast to MMAO catalyst system, a less amount of Et 2 AlCl to (-diimine)Ni(II) is enough to reach a high active for the polymerization, and (-diimine)Ni(II)/Et 2 AlCl catalyst gave an optimum rate at the Al/Ni mole ratio of about 20 for the polymerization of trans-2-butene. The results obtained from a kinetic study demonstrate that the control of molecular weight is possible in the polymerization of trans-2-butene with (-diimine A large amount of 2-olefins such as 2-butene is produced by naphtha cracking products, but they have not been utilized as monomers because of their low reactivity toward polymerization catalysts. If these olefins polymerize easily to give high molecular weight polymers, a large amount of 2-olefins will be expected to become new polymer materials. Nevertheless, a few studies on the polymerization of 2-olefins by transition metal complexes have been reported. [1][2][3][4][5] One example is a copolymerization of 2-butene with ethylene by transition metal catalysts.1-3 Monomer-isomerization polymerization of 2-olefins with Ziegler-Natta catalysts is another example. In the monomer-isomerization polymerization, various 2-olefins including cis-2-butene and trans-2-butene give high molecular weight polymers with a recurring unit of the corresponding 1-olefins. This polymerization mechanism can be explained by the polymerization of 1-olefins produced by isomerization of charged 2-olefins prior to the polymerization, 4,5 and consumed 1-olefins are supplied by isomerization through a equilibrium of the isomers.Recently, Brookhart et al. 6 discovered a new type polymerization of trans-2-butene with some kinds of (-diimine)Ni(II) complexes in combination with modified-methylaluminoxane (MMAO). In the polymerization, trans-2-butene gave a high molecular weight polymer having a microstructure with one methyl branch for every four carbon atoms. This polymerization mechanism can be explained by a series of -hydride elimination/re-addition reactions instead of a direct opening of double bond. Moreover, the effect of MAO as a cocatalyst for the (-diimine)Ni(II) complexes on the polymerization of trans-2-butene was examined. The polymerization proceeded with MMAO, although a large amount of MMAO was also needed to reach a high activity for the polymerization. On the other hand, when methylaluminoxane (P-MAO) was used as a cocatalyst, no polymerization was induced. This indicates that the cocatalyst play a role in the polymerization of trans-2-butene with (-diimine)Ni(II) complexes.After a discovery of the polymerization of trans-2-butene with (-diimine)Ni(II)/MMAO catalyst, a chiral catal...

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“…Higher α-olefins, such as propylene and 1-hexene, have also been polymerised into amorphous or atactic polymers with these catalysts [17]. Through variations in the ligand design, reaction conditions and type of monomer used, novel elastomeric multiblock poly(α-olefin) [19][20][21][22] and regioblock co-polymers [26][27][28] have been synthesised. In particular, cationic nickel(II) catalysts have been found to produce polyethylene, polypropylene and poly(1-hexene) [29][30][31][32][33] that have significant branching.…”

Section: Introductionmentioning

confidence: 99%

Homo-Polymerization of 1-Hexene Catalysed by O^N^N (Salicylaldimine)Iron(III) Pre-Catalysts to Branched Poly(1-hexene)

2016

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A C₂-Symmetric, Living α-Diimine Ni(II) Catalyst: Regioblock Copolymers from Propylene

Cited by 213 publications

References 14 publications

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Polymerization of trans-2-Butene with (α-Diimine)Ni(II) Complex in Combination with Et2AlCl

Homo-Polymerization of 1-Hexene Catalysed by O^N^N (Salicylaldimine)Iron(III) Pre-Catalysts to Branched Poly(1-hexene)

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A C2-Symmetric, Living α-Diimine Ni(II) Catalyst: Regioblock Copolymers from Propylene

Cited by 213 publications

References 14 publications

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Semicrystalline thermoplastic elastomeric polyolefins: Advances through catalyst development and macromolecular design

Polymerization of trans-2-Butene with (α-Diimine)Ni(II) Complex in Combination with Et2AlCl

Homo-Polymerization of 1-Hexene Catalysed by O^N^N (Salicylaldimine)Iron(III) Pre-Catalysts to Branched Poly(1-hexene)

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A C₂-Symmetric, Living α-Diimine Ni(II) Catalyst: Regioblock Copolymers from Propylene