Sequential two-stage polymerization for synthesis of isotactic polypropylene/isotactic polybutene-1 alloys: composition, morphology and granule growing mechanism

Jiang, Baiyu; Shao, Hongbo; Nie, Huarong; He, Aihua

doi:10.1039/c5py00205b

Cited by 18 publications

(19 citation statements)

References 28 publications

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“…As in the case of TMC‐H catalyst, polymerization is likely to proceed on microcrystallite surface of the TMC‐M catalyst. However, owing to a more dense packing of microcrystallites and microparticles in subparticles of this catalyst, there is a more complete filling of the volume of subparticles with the growing polymer in which microcrystallites of the catalyst are distributed (multigrain model or a recently proposed model with carry‐over of the catalyst microparticles to the surface of a growing polymer subparticle) . Finally, the PE‐2 macroparticle consists of dense 25–35 μm subparticles (Table ).…”

Section: Resultsmentioning

confidence: 99%

Effect of the structure of titanium–magnesium catalysts on the morphology of polyethylene produced

Mikenas

Koshevoy

Захаров

2017

J. Polym. Sci. Part A: Polym. Chem.

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The structure and formation of polyethylene (PE) particles on supported titanium–magnesium catalysts having different structural characteristics (sizes of microcrystallites, mesopores, and subparticles) were studied for the first time. Scanning electron microscopy was used to identify structural elements of the polymer particles formed over such catalysts and to reveal morphological changes in the growing polymer particles when the yield was increased from approximately 0.2 g PE/g catalyst to approximately 13 kg PE/g catalyst. A relationship was found between structural characteristics of the porous catalyst particles, morphology of the nascent polymer particles, and bulk density of the polymer powder. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2298–2308

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Section: Resultsmentioning

confidence: 99%

Effect of the structure of titanium–magnesium catalysts on the morphology of polyethylene produced

Mikenas

Koshevoy

Захаров

2017

J. Polym. Sci. Part A: Polym. Chem.

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“…The generated precipitates (presumably lauroyl zinc) and polar compounds (CH 3 (CH 2 ) 7 -O(O)C(CH 2 ) 10 CH 3 and unreacted lauroyl peroxide) were removed by filtration through a short pad of silica gel. Meanwhile, the 1 H and 13 C NMR spectra of the filtrate clearly indicated that the generated hydrocarbon was hexadecane, the coupling product of the octyl group (Figure 2d and Figure S1).…”

Section: ■ Introductionmentioning

confidence: 99%

Peroxide-Mediated Alkyl–Alkyl Coupling of Dialkylzinc: A Useful Tool for Synthesis of ABA-Type Olefin Triblock Copolymers

Kim

Kwon

et al. 2018

Macromolecules

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A practical and simple method for the preparation of ABA-type olefin triblock copolymers, e.g., PE-b-poly(ethylene-co-propylene)-b-PE, has been described. The performance of the so-called “coordinative chain transfer polymerization” (CCTP) by sequential feed of ethylene and ethylene/propylene mixed gas generated a Zn-bound diblock copolymer (i.e., (PE-b-poly(ethylene-co-propylene)yl)2Zn). Treatment of the Zn-bound diblock copolymer with lauroyl peroxide (CH3(CH2)10C(O)O-OC(O)(CH2)10CH3) led to a C(sp3)–C(sp3) coupling reaction between the two diblock chains bound on the zinc site and an ABA-type olefin triblock copolymer, PE-b-poly(ethylene-co-propylene)-b-PE, was formed. Upon the treatment with lauroyl peroxide, the number-average molecular weight increased by 1.5–1.7 times. The occurrence of the coupling reaction was verified using a model compound, (Oct)2Zn. The ABA-type triblock copolymer exhibited thermoplastic elastomeric properties and dramatically improved mechanical properties (twice the tensile strength and 10-fold increase in the elongation at break) as compared to the diblock congener.

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“…Block copolymers are a remarkable class of materials with widespread applications in mundane plastics as well as in high technological devices and are well-researched in polymer chemistry. − Polyolefins (POs), including polyethylene (PE) and polypropylene (PP), are the most abundant polymers. The annual production of these polymers is currently more than 120 million metric tons, and preparation of PO-based block copolymers is of immense interest in both industry and academia. − In fact, Dow Chemical Company commercialized olefin block copolymers (OBCs) since a decade ago. − OBCs are produced by employing the so-called “coordinative chain transfer polymerization (CCTP)” technique, which involves the use of a single transition-metal-based catalyst (e.g., Hf catalyst) and a chain transfer agent (CTA, e.g., Et 2 Zn) in excess ([Zn]/[Hf] > 100). In CCTP, the growing polymeryl group in the catalyst is reversibly and rapidly exchanged with the alkyl group in the CTA, resulting in uniform PO-chain growth from the CTA. , The CCTP technique is currently used for precise architectural design as well as end-group functionalization of PO. − …”

Section: Introductionmentioning

confidence: 99%

Biaxial Chain Growth of Polyolefin and Polystyrene from 1,6-Hexanediylzinc Species for Triblock Copolymers

Park

Kim

et al. 2017

Macromolecules

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Synthesis of polyolefin (PO)-based block copolymers is of immense research interest. In this work, we report a strategy for the construction of polystyrene (PS)-block-PO-block-PS, a useful thermoplastic elastomer, directly from olefin and styrene monomers. Multinuclear zinc species Et[Zn(CH2)6] a ZnEt were prepared through successive additions of BH3 and Et2Zn to 1,5-hexadiene. Poly(ethylene-co-propylene) chains were biaxially grown from the −(CH2)6– units in Et[Zn(CH2)6] a ZnEt via “coordinative chain transfer polymerization (CCTP)” using the pyridylaminohafnium catalyst. PS chains were subsequently grown in one pot from the generated polymeryl–Zn sites by subsequent introduction of the anionic initiator Me3SiCH2Li·(pmdeta) (pmdeta, pentamethyldiethylenetriamine) and styrene monomers. The fraction of the extracted PS homopolymer grown from the Me3SiCH2 sites was low (homo-PS (g)/total PS (g), 15–22%). The gel permeation chromatography (GPC) curves shifted evidently after styrene polymerization, and change in the molecular weight (ΔM n, 39–56 kDa) was approximately twice the homo-PS M n (20–23 kDa), in accordance with attachment of the PS chains at both ends of the PO chains. Transmission electron microscopy analysis of the thin films showed segregation of the PS domains in the PO matrix to form spherical or wormlike rippled structures depending on the PS content. The prepared triblock copolymers exhibited elastomeric properties in the cyclic tensile test, similar to the commercial PS-block-poly(ethylene-co-1-butene)-block-PS.

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Sequential two-stage polymerization for synthesis of isotactic polypropylene/isotactic polybutene-1 alloys: composition, morphology and granule growing mechanism

Abstract: A crystalline/crystalline iPP/iPB alloy was synthesized to illustrate the sequential two-stage polymerization mechanism and active site distribution during this process.

Cited by 18 publications

References 28 publications

Effect of the structure of titanium–magnesium catalysts on the morphology of polyethylene produced

Effect of the structure of titanium–magnesium catalysts on the morphology of polyethylene produced

Peroxide-Mediated Alkyl–Alkyl Coupling of Dialkylzinc: A Useful Tool for Synthesis of ABA-Type Olefin Triblock Copolymers

Biaxial Chain Growth of Polyolefin and Polystyrene from 1,6-Hexanediylzinc Species for Triblock Copolymers

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