Special Issue "Olefin Polymerization and Polyolefin"

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (25 October 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Changle Chen

Department of Polymer Science and Engineering, University of Science & Technology of China, Jinzhai Rd 96, Hefei, China
Website | E-Mail
Interests: metal-based polymerization catalysts; olefin polymerization; polar monomers; ring-opening polymerization; carbon-based nano-materials; industrial engineering polymers

Special Issue Information

Dear Colleagues,

Since the Nobel Prize winning discovery made by Ziegler and Natta, transition-metal-catalyzed olefin polymerization has enjoyed great success in both industry and academia. Currently, polyolefin materials constitute almost half of the 300 million tons of the worldwide plastics production. The development of new olefin polymerization catalysts has been a major driving force in this field. Despite decades of research, there are still a lot of unsolved issues. It is believed that the polyolefin research and the polyolefin industry will keep moving forward through the design of new catalysts and new polymerization strategies, as well as the development of new polymer reaction engineering and polymer process technologies.

This Special Issue focuses on the latest achievements in the field of olefin polymerization. This Special Issue invites original papers and reviews concerning the development of new catalysts, new polymerization techniques, insights into the polymerization mechanism, polymer characterization, polymer applications, and the application of existing metal catalysts for the synthesis of new polymeric materials.

Prof. Dr. Changle Chen
Guest Editor

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Keywords

  • Olefin polymerization

  • Polyolefin

  • Catalysts

  • Copolymerization

  • Mechanism

  • Characterization

  • Early transition metal catalysts

  • Late transition metal catalysts

  • Polar monomers

Published Papers (21 papers)

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Research

Open AccessArticle A Novel Ziegler–Natta-Type Catalytic System—TiCl4/2,2′-Dimethoxy-1,1′-Binaphthalene/Et3Al2Cl3/Bu2Mg for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solvent-Free Processing
Polymers 2018, 10(11), 1281; https://doi.org/10.3390/polym10111281 (registering DOI)
Received: 29 October 2018 / Revised: 14 November 2018 / Accepted: 15 November 2018 / Published: 17 November 2018
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Abstract
A series of ultrahigh molecular weight polyethylenes with viscosity-average molecular weights in the range of 1.6–5.6 × 106 have been prepared by using a novel Ziegler–Natta-type catalytic system—TiCl4/2,2′-dimethoxy-1,1′-binaphthalene/Et3Al2Cl3/Bu2Mg at different temperatures (
[...] Read more.
A series of ultrahigh molecular weight polyethylenes with viscosity-average molecular weights in the range of 1.6–5.6 × 106 have been prepared by using a novel Ziegler–Natta-type catalytic system—TiCl4/2,2′-dimethoxy-1,1′-binaphthalene/Et3Al2Cl3/Bu2Mg at different temperatures (Tpoly) in the range between 10 and 70 °C in toluene. The morphology of the nascent reactor powders has been studied by scanning electron microscopy, wide-angle X-ray diffraction, and the DSC melting behavior. Polymers are suitable for the modern processing methods—the solvent-free solid-state formation of super high-strength (tensile strength over 1.8–2.5 GPa) and high-modulus (elastic modulus up to 136 GPa) oriented film tapes. With decrease of Tpoly, the drawability of the reactor powders increased significantly. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle α,ω-Epoxide, Oxetane, and Dithiocarbonate Telechelic Copolyolefins: Access by Ring-Opening Metathesis/Cross-Metathesis Polymerization (ROMP/CM) of Cycloolefins in the Presence of Functional Symmetric Chain-Transfer Agents
Polymers 2018, 10(11), 1241; https://doi.org/10.3390/polym10111241
Received: 16 October 2018 / Revised: 3 November 2018 / Accepted: 4 November 2018 / Published: 9 November 2018
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Abstract
Epoxide- and oxetane-α,ω-telechelic (co)polyolefins have been successfully synthesized by the tandem ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) of cyclic olefins using Grubbs’ second-generation catalyst (G2) in the presence of a bifunctional symmetric alkene epoxide- or oxetane-functionalized chain-transfer agent (CTA). From cyclooctene (COE),
[...] Read more.
Epoxide- and oxetane-α,ω-telechelic (co)polyolefins have been successfully synthesized by the tandem ring-opening metathesis polymerization (ROMP)/cross-metathesis (CM) of cyclic olefins using Grubbs’ second-generation catalyst (G2) in the presence of a bifunctional symmetric alkene epoxide- or oxetane-functionalized chain-transfer agent (CTA). From cyclooctene (COE), trans,trans,cis-1,5,9-cyclododecatriene (CDT), norbornene (NB), and methyl 5-norbornene-2-carboxylate (NBCOOMe), with bis(oxiran-2-ylmethyl) maleate (CTA 1), bis(oxetane-2-ylmethyl) maleate (CTA 2), or bis(oxetane-2-ylmethyl) (E)-hex-3-enedioate (CTA 3), well-defined α,ω-di(epoxide or oxetane) telechelic PCOEs, P(COE-co-NB or -NBCOOMe)s, and P(NB-co-CDT)s were isolated under mild operating conditions (40 or 60 °C, 24 h). The oxetane CTA 3 and the epoxide CTA 1 were revealed to be significantly more efficient in the CM step than CTA 2, which apparently inhibits the reaction. Quantitative dithiocarbonatation (CS2/LiBr, 40 °C, THF) of an α,ω-di(epoxide) telechelic P(NB-co-CDT) afforded a convenient approach to the analogous α,ω-bis(dithiocarbonate) telechelic P(NB-co-CDT). The nature of the end-capping function of the epoxide/oxetane/dithiocarbonate telechelic P(NB-co-CDT)s did not impact their thermal signature, as measured by DSC. These copolymers also displayed a low viscosity liquid-like behavior and a shear thinning rheological behavior. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Influences of Fluorine Substituents on Iminopyridine Fe(II)- and Co(II)-Catalyzed Isoprene Polymerization
Polymers 2018, 10(9), 934; https://doi.org/10.3390/polym10090934
Received: 15 July 2018 / Revised: 16 August 2018 / Accepted: 18 August 2018 / Published: 22 August 2018
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Abstract
A series of iminopyridine complexes of Fe(II) and Co(II) complexes bearing fluorinated aryl substituents were synthesized for the polymerization of isoprene. The structures of complexes 3a, 2b and 3b were determined by X-ray diffraction analysis. Complex 3a contained two iminopyridine ligands coordinated
[...] Read more.
A series of iminopyridine complexes of Fe(II) and Co(II) complexes bearing fluorinated aryl substituents were synthesized for the polymerization of isoprene. The structures of complexes 3a, 2b and 3b were determined by X-ray diffraction analysis. Complex 3a contained two iminopyridine ligands coordinated to the iron metal center forming an octahedral geometry, whereas 2b adopted a chloro-bridged dimer, and 3b featured with two patterns of cobalt centers bridged via chlorine atoms. Complexes 2b and 3b represented rare examples of chlorine bridged bimetallic Co(II) complexes. The fluorine substituents effects, particularly on catalytic activity and polymer properties such as molecular weight and regio-/stereo-selectivity were investigated when these complexes were employed for isoprene polymerization. Among the Fe(II)/methylaluminoxane (MAO) systems, the 4-CF3 substituted iminopyridine Fe(II) complex 1a was found as a highly active isoprene polymerization catalyst exhibiting the highest activity of 106 g·(mol of Fe)−1·h−1. The resultant polymer displayed lower molecular weight (Mn = 3.5 × 104 g/mol) and moderate polydispersity index (PDI = 2.1). Furthermore, the ratio of cis-1,4-/3,4 was not affected by the F substituents. In the series of Co(II)/AlEt2Cl binary systems, complexes containing electron-withdrawing N-aryl substituents (R = 4-CF3, 2,6-2F) afforded higher molecular weights polyisoprene than that was obtained by the complex containing electron-donating N-alkyl substituents (R = octyl). However, ternary components system, complex/MAO/[Ph3C][B(C6F5)4] resulted in low molecular weight polyisoprene (Mn < 2000) with high trans-1,4-unit (>95%). Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Multi-Alkenylsilsesquioxanes as Comonomers and Active Species Modifiers of Metallocene Catalyst in Copolymerization with Ethylene
Polymers 2018, 10(2), 223; https://doi.org/10.3390/polym10020223
Received: 24 January 2018 / Revised: 16 February 2018 / Accepted: 22 February 2018 / Published: 24 February 2018
Cited by 2 | PDF Full-text (4860 KB) | HTML Full-text | XML Full-text
Abstract
The copolymers of ethylene (E) with open-caged iso-butyl-substituted tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) and phenyl-substituted tetra-alkenyl-silsesquioxane (POSS-10-4) were synthesized by copolymerization over the ansa-metallocene catalyst. The influence of the kind of silsesquioxane and of the copolymerization conditions on the reaction performance and on
[...] Read more.
The copolymers of ethylene (E) with open-caged iso-butyl-substituted tri-alkenyl-silsesquioxanes (POSS-6-3 and POSS-10-3) and phenyl-substituted tetra-alkenyl-silsesquioxane (POSS-10-4) were synthesized by copolymerization over the ansa-metallocene catalyst. The influence of the kind of silsesquioxane and of the copolymerization conditions on the reaction performance and on the properties of the copolymers was studied. In the case of copolymerization of E/POSS-6-3, the positive comonomer effect was observed, which was associated with the influence of POSS-6-3 on transformation of the bimetallic ion pair to the active catalytic species. Functionality of silsesquioxanes and polymerization parameters affected the polyhedral oligomeric silsesquioxanes (POSS) contents in the copolymers which varied in the range of 1.33–7.43 wt %. Tri-alkenyl-silsesquioxanes were incorporated into the polymer chain as pendant groups while the tetra-alkenyl-silsesquioxane derivative could act as a cross-linking agent which was proved by the changes in the contents of unsaturated end groups, by the glass transition temperature values, and by the gel contents (up to 81.3% for E/POSS-10-4). Incorporation of multi-alkenyl-POSS into the polymer chain affected also the melting and crystallization behaviors. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle The Dispersion of Pulp-Fiber in High-Density Polyethylene via Different Fabrication Processes
Polymers 2018, 10(2), 122; https://doi.org/10.3390/polym10020122
Received: 13 December 2017 / Revised: 17 January 2018 / Accepted: 24 January 2018 / Published: 26 January 2018
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Abstract
In this study, a pulp beating machine was used to premix the pulp fibers with high density polyethylene (HDPE) particles in water. The wet or pre-dried pulp fiber/HDPE mixture was then melt-compounded by a twin screw extruder. For further improving the dispersion of
[...] Read more.
In this study, a pulp beating machine was used to premix the pulp fibers with high density polyethylene (HDPE) particles in water. The wet or pre-dried pulp fiber/HDPE mixture was then melt-compounded by a twin screw extruder. For further improving the dispersion of pulp fiber, some mixture was forced to pass through the twin-screw extruder twice. The resulting mixture was compression molded to the composite. The fiber distribution was observed by the aid of an optic and scanning electron microscope. The mechanical and rheological properties and creep resistance of the composites were characterized. Test results demonstrate that when the wet pulp fiber/HDPE mixture was subjected to pre-pressing and oven drying prior to extrusion compounding, the resulting composites exhibited homogeneous fiber distribution, superior flexural property, creep-resistance, and high storage modulus. Particularly, its flexural strength and modulus were 57% and 222% higher, respectively, than that of the neat HDPE, while the composites prepared without pre-dried were 19% and 100% higher, respectively. Drying the wet mixture in advance is more effective than re-passing through the extruder for improving the fiber dispersion and composite performance. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle High Temperature, Living Polymerization of Ethylene by a Sterically-Demanding Nickel(II) α-Diimine Catalyst
Polymers 2018, 10(1), 41; https://doi.org/10.3390/polym10010041
Received: 15 December 2017 / Revised: 27 December 2017 / Accepted: 27 December 2017 / Published: 2 January 2018
Cited by 1 | PDF Full-text (1171 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Catalysts that employ late transition-metals, namely Ni and Pd, have been extensively studied for olefin polymerizations, co-polymerizations, and for the synthesis of advanced polymeric structures, such as block co-polymers. Unfortunately, many of these catalysts often exhibit poor thermal stability and/or non-living polymerization behavior
[...] Read more.
Catalysts that employ late transition-metals, namely Ni and Pd, have been extensively studied for olefin polymerizations, co-polymerizations, and for the synthesis of advanced polymeric structures, such as block co-polymers. Unfortunately, many of these catalysts often exhibit poor thermal stability and/or non-living polymerization behavior that limits their ability to access tailored polymer structures. Due to this, the development of catalysts that display controlled/living behavior at elevated temperatures is vital. In this manuscript, we describe a Ni α-diimine complex that is capable of polymerizing ethylene in a living manner at temperatures as high as 75 °C, which is one of the highest temperatures reported for the living polymerization of ethylene by a late transition metal-based catalyst. Furthermore, we will demonstrate that this catalyst’s living behavior is not dependent on the presence of monomer, and that it can be exploited to access polyethylene-based block co-polymers. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Titanium(III, IV)-Containing Catalytic Systems for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solventless Processing—Impact of Oxidation States of Transition Metal
Polymers 2018, 10(1), 2; https://doi.org/10.3390/polym10010002
Received: 4 December 2017 / Revised: 16 December 2017 / Accepted: 18 December 2017 / Published: 21 December 2017
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Abstract
Catalytic systems containing TiCl4 or TiCl3, THF, organomagnesium (n-Bu2Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8–7.8)
[...] Read more.
Catalytic systems containing TiCl4 or TiCl3, THF, organomagnesium (n-Bu2Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8–7.8) × 106 Da and desirable morphology, suitable for modern methods of polymer processing—the solvent-free solid-state processing of superhigh-strength (tensile strength up to 2.1 GPa) and high-modulus (elastic modulus up to 125 GPa) oriented films and film tapes. The impacts of a THF additive, the oxidation state of the titanium atom, and the composition and nature of the nontransition organometallic compounds on the formation of catalytic systems for UHMWPE production were evaluated. The results indicate the suitability of individual titanium chloride tetrahydrofuran complex application for the formation of THF-containing catalytic systems. This approach also results in a significant increase in the system catalytic activity and mechanical properties of UHMWPE. The catalysts based on Ti(III) were inferior to systems containing Ti(IV) in productivity but were markedly superior in the mechanical properties of UHMWPE. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Substituent Effects of Adamantyl Group on Amido Ligand in Syndiospecific Polymerization of Propylene with Ansa-Dimethylsilylene(Fluorenyl)(Amido) Zirconium Complex
Polymers 2017, 9(11), 632; https://doi.org/10.3390/polym9110632
Received: 21 October 2017 / Revised: 13 November 2017 / Accepted: 16 November 2017 / Published: 21 November 2017
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Abstract
A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl group on the amido ligand were synthesized and characterized by elemental analysis, 1H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the zirconium metal was
[...] Read more.
A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl group on the amido ligand were synthesized and characterized by elemental analysis, 1H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the zirconium metal was η3 manner, and all the complexes were Cs-symmetric in solution. The complexes showed moderate activity (1.0 × 105 g-polymer mol-Zr−1·h−1), even at a low Al/Zr ratio of 50. The increase of propylene pressure improved the activity by one order of magnitude (up to 1.0 × 106 g-polymer mol-Ti−1·h−1). All catalyst systems gave syndiotactic polypropylene, where the complex containing the 3,6-di-t-butyl fluorenyl ligand was more effective for the enhancement of the syndiospecificity. The increase of propylene pressure also improved the syndiospecificity with the syndiotactic pentad of 0.96 and the melting point of 159 °C. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle The Dynamic Mechanical Analysis of Highly Filled Rice Husk Biochar/High-Density Polyethylene Composites
Polymers 2017, 9(11), 628; https://doi.org/10.3390/polym9110628
Received: 27 October 2017 / Revised: 14 November 2017 / Accepted: 15 November 2017 / Published: 17 November 2017
Cited by 2 | PDF Full-text (3446 KB) | HTML Full-text | XML Full-text
Abstract
In this study, rice husk biochar/high-density polyethylene (HDPE) composites were prepared via melt mixing followed by extrusion. Effects of biochar content and testing temperature on the dynamic mechanical analysis (DMA) of the composites were studied. Morphological analysis of the rice husk biochar and
[...] Read more.
In this study, rice husk biochar/high-density polyethylene (HDPE) composites were prepared via melt mixing followed by extrusion. Effects of biochar content and testing temperature on the dynamic mechanical analysis (DMA) of the composites were studied. Morphological analysis of the rice husk biochar and composites were evaluated by scanning electron microscopy (SEM). The results showed that biochar had a positive effect on dynamic viscoelasticity, creep resistance and stress relaxation properties of the composites, but the creep resistance and stress relaxation of the composites decreased with the increase of temperature. SEM analysis showed that HDPE components were embedded in the holes of the rice husk biochar, and it is believed that strong interaction was achieved. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle MgCl2-Supported Titanium Ziegler-Natta Catalyst Using Carbon Dioxide-Based Poly(propylene ether carbonate) Diols as Internal Electron Donor for 1-Butene Polymerization
Polymers 2017, 9(11), 627; https://doi.org/10.3390/polym9110627
Received: 10 October 2017 / Revised: 4 November 2017 / Accepted: 14 November 2017 / Published: 17 November 2017
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Abstract
MgCl2-supported titanium Ziegler-Natta catalyst containing CO2-based poly(propylene ether carbonate) diols as a potential internal electron donor (IED) was synthesized and employed for 1-butene polymerization. When compared with the Ziegler-Natta catalyst using poly(polypropylene glycol) as IED, the catalyst prepared with
[...] Read more.
MgCl2-supported titanium Ziegler-Natta catalyst containing CO2-based poly(propylene ether carbonate) diols as a potential internal electron donor (IED) was synthesized and employed for 1-butene polymerization. When compared with the Ziegler-Natta catalyst using poly(polypropylene glycol) as IED, the catalyst prepared with poly(propylene ether carbonate) diols showed good particle morphology, higher activity and stereoselectivity. The results suggested that existence of the carbonate group within the structure of poly(propylene ether carbonate) diols truly plays an important role in improving the performance of the catalyst for the 1-butene polymerization. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Propene Polymerization with C1-Symmetric Fluorenyl-Metallocene Catalysts
Polymers 2017, 9(11), 581; https://doi.org/10.3390/polym9110581
Received: 11 October 2017 / Revised: 30 October 2017 / Accepted: 31 October 2017 / Published: 6 November 2017
Cited by 1 | PDF Full-text (4132 KB) | HTML Full-text | XML Full-text
Abstract
Propene homopolymers have been produced by employing three C1-symmetric metallocene molecules (1, 2 and 3), each having t-butyl substituent(s) on the Cp, on the fluorenyl or on both aromatic moieties activated with methylaluminoxane at different polymerization
[...] Read more.
Propene homopolymers have been produced by employing three C1-symmetric metallocene molecules (1, 2 and 3), each having t-butyl substituent(s) on the Cp, on the fluorenyl or on both aromatic moieties activated with methylaluminoxane at different polymerization temperatures and monomer concentrations. Polymers’ microstructures determined by 13C NMR spectroscopy suggest that the otherwise dominant alternating mechanism governed by the chain migratory insertion is largely replaced by the competing site epimerization mechanism, as a direct result of the imposing steric bulk of the t-butyl substituent on one of the distal positions of the Cp moiety. This phenomenon is more pronounced with 3 when a second t-butyl is present in the same half-space of the molecule making the site epimerization mandatory. The lower activity of catalyst 3 with respect to catalyst 2 is also in line with the necessity for the polymer chain to back-skip (or the site to epimerize) to its original position before the subsequent monomer insertion. Chain end group analyses by 1H NMR spectroscopy have revealed that the formation of vinylidene end groups, either via β-H elimination or as a result of direct chain transfer to the monomer after an ordinary 1,2-insertion is the prevailing chain termination route. A correlation between the relative concentrations of vinylidene end groups of polypropene (PP) polymers produced with each catalyst and the corresponding polypropenes’ molar masses was found, indicating the lower the relative concentrations of vinylidene end groups, the higher the molar masses. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Cis-1,4-Polymerization of Isoprene by 1,3-Bis(oxazolinymethylidene)isoindoline-Ligated Rare-Earth Metal Dialkyl Complexes
Polymers 2017, 9(10), 531; https://doi.org/10.3390/polym9100531
Received: 29 September 2017 / Revised: 17 October 2017 / Accepted: 18 October 2017 / Published: 20 October 2017
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Abstract
A series of novel chiral nonmetallocene pincer-type rare-earth metal dialkyl complexes bearing the chiral monoanionic tridentate C2-symmetric 1,3-bis(oxazolinymethylidene)isoindoline (BOXMI-H) ligand (BOXMI)Ln(CH2SiMe3)2 1–3 (1: Ln = Sc, yield = 57%; 2: Ln = Lu, yield = 55%;
[...] Read more.
A series of novel chiral nonmetallocene pincer-type rare-earth metal dialkyl complexes bearing the chiral monoanionic tridentate C2-symmetric 1,3-bis(oxazolinymethylidene)isoindoline (BOXMI-H) ligand (BOXMI)Ln(CH2SiMe3)2 1–3 (1: Ln = Sc, yield = 57%; 2: Ln = Lu, yield = 55%; 3: Ln = Y, yield = 62%) have been prepared in moderate yields via the acid-base reaction between the BOXMI ligand and rare-earth metal tri(trimethylsilylmethyl) complexes. The X-ray diffractions show that both of the complexes 1 and 2 contain one BOXMI ligand and two trimethylsilylmethyl ligands, adopting a distorted trigonal bipyramidal configuration. In the presence of a cocatalyst such as borate and AlR3, these complexes 1–3 exhibit high activities of up to 6.8 × 104 (g of polymer)/(molLn h) and high cis-1,4 selectivities of up to 97% in the polymerization of isoprene in toluene, yielding the cis-1,4-polyisoprenes with heavy molecular weights (Mn of up to 710,000 g/mol) and bimodal molecular weight distributions (Mw/Mn = 2.0–4.5). Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle A Single-Site Iron(III)-Salan Catalyst for Converting COS to Sulfur-Containing Polymers
Polymers 2017, 9(10), 515; https://doi.org/10.3390/polym9100515
Received: 22 September 2017 / Revised: 9 October 2017 / Accepted: 11 October 2017 / Published: 17 October 2017
Cited by 2 | PDF Full-text (2892 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
An iron(III) complex of tetradentate N,N′-disubstituted bis(aminophenoxide) (designated as salan, a saturated version of the corresponding salen ligand) with a sterically hindered organic base anchored on the ligand framework, can selectively mediate the conversion of carbonyl sulfide to sulfur-containing polymers
[...] Read more.
An iron(III) complex of tetradentate N,N′-disubstituted bis(aminophenoxide) (designated as salan, a saturated version of the corresponding salen ligand) with a sterically hindered organic base anchored on the ligand framework, can selectively mediate the conversion of carbonyl sulfide to sulfur-containing polymers by the copolymerization with epoxides. This single-site catalyst exhibits broad substrate scope, and the resultant copolymers have completely alternating structures. In addition, this catalyst is efficient in producing diblock copolymers, suggesting a living polymerization nature. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Preparation of Isotactic Polypropylene/Exfoliated MoS2 Nanocomposites via In Situ Intercalative Polymerization
Polymers 2017, 9(10), 490; https://doi.org/10.3390/polym9100490
Received: 22 September 2017 / Revised: 30 September 2017 / Accepted: 30 September 2017 / Published: 7 October 2017
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Abstract
In this research, a Ziegler–Natta catalyst intercalated MoS2 was synthesized through the intercalation of a Grignard reagent into MoS2 galleries, followed by the anchoring of TiCl4. During propylene polymerization, the intercalated MoS2 exfoliated in situ to form PP/exfoliated MoS2
[...] Read more.
In this research, a Ziegler–Natta catalyst intercalated MoS2 was synthesized through the intercalation of a Grignard reagent into MoS2 galleries, followed by the anchoring of TiCl4. During propylene polymerization, the intercalated MoS2 exfoliated in situ to form PP/exfoliated MoS2 (EMoS2) nanocomposites. The isotactic index values of the resultant PP/EMoS2 nanocomposites were as high as 99%, varying from 98.1% to 99.0%. It was found that the incorporation of the EMoS2 significantly improved the thermal stability and mechanical properties (tensile strength, modulus, and elongation at break) of PP. After introduction of EMoS2, the maximum increases in Td5% and Tdmax were 36.9 and 9.7 °C, respectively, relative to neat PP. After blending with commercial PP, the resultant nanocomposites increase in tensile strength and modulus up to 11.4% and 61.2% after 0.52 wt % EMoS2 loading. Thus, this work provides a new way to produce high-performance PP. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Polystyrene Chain Growth from Di-End-Functional Polyolefins for Polystyrene-Polyolefin-Polystyrene Block Copolymers
Polymers 2017, 9(10), 481; https://doi.org/10.3390/polym9100481
Received: 28 August 2017 / Revised: 19 September 2017 / Accepted: 29 September 2017 / Published: 2 October 2017
Cited by 2 | PDF Full-text (2060 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Triblock copolymers of polystyrene (PS) and a polyolefin (PO), e.g., PS-block-poly(ethylene-co-1-butene)-block-PS (SEBS), are attractive materials for use as thermoplastic elastomers and are produced commercially by a two-step process that involves the costly hydrogenation of PS-block-polybutadiene-
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Triblock copolymers of polystyrene (PS) and a polyolefin (PO), e.g., PS-block-poly(ethylene-co-1-butene)-block-PS (SEBS), are attractive materials for use as thermoplastic elastomers and are produced commercially by a two-step process that involves the costly hydrogenation of PS-block-polybutadiene-block-PS. We herein report a one-pot strategy for attaching PS chains to both ends of PO chains to construct PS-block-PO-block-PS directly from olefin and styrene monomers. Dialkylzinc compound containing styrene moieties ((CH2=CHC6H4CH2CH2)2Zn) was prepared, from which poly(ethylene-co-propylene) chains were grown via “coordinative chain transfer polymerization” using the pyridylaminohafnium catalyst to afford di-end functional PO chains functionalized with styrene and Zn moieties. Subsequently, PS chains were attached at both ends of the PO chains by introduction of styrene monomers in addition to the anionic initiator Me3SiCH2Li·(pmdeta) (pmdeta = pentamethyldiethylenetriamine). We found that the fraction of the extracted PS homopolymer was low (~20%) and that molecular weights were evidently increased after the styrene polymerization (ΔMn = 27–54 kDa). Transmission electron microscopy showed spherical and wormlike PS domains measuring several tens of nm segregated within the PO matrix. Optimal tensile properties were observed for the sample containing a propylene mole fraction of 0.25 and a styrene content of 33%. Finally, in the cyclic tensile test, the prepared copolymers exhibited thermoplastic elastomeric properties with no breakage up over 10 cycles, which is comparable to the behavior of commercial-grade SEBS. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Facile, Efficient Copolymerization of Ethylene with Norbornene-Containing Dienes Promoted by Single Site Non-Metallocene Oxovanadium(V) Catalytic System
Polymers 2017, 9(8), 353; https://doi.org/10.3390/polym9080353
Received: 23 July 2017 / Revised: 8 August 2017 / Accepted: 8 August 2017 / Published: 11 August 2017
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Abstract
Non-metallocene oxovanadium(V) complexes bearing either [ONNO]-type amine pyridine bis(phenolate) ligands or [ONN]-type amine pyridine phenolate ligands were employed as efficient catalysts to copolymerize ethylene with several unsymmetrical norbornene-containing dienes, such as 5-vinyl-2-norbornene (VNB), 5-ethylidene-2-norbornene (ENB) or dicyclopentadiene (DCPD), producing copolymers with high comonomer
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Non-metallocene oxovanadium(V) complexes bearing either [ONNO]-type amine pyridine bis(phenolate) ligands or [ONN]-type amine pyridine phenolate ligands were employed as efficient catalysts to copolymerize ethylene with several unsymmetrical norbornene-containing dienes, such as 5-vinyl-2-norbornene (VNB), 5-ethylidene-2-norbornene (ENB) or dicyclopentadiene (DCPD), producing copolymers with high comonomer incorporations (VNB: 33.0 mol %; ENB: 30.4 mol %; DCPD: 31.6 mol %, respectively) and high molecular weight (VNB: 86.4 kDa; ENB: 256 kDa; DCPD: 86.4 kDa, respectively). The enchainment of the dienes was proven to be exclusive of vinyl-addition via the C=C double bond of the norbornene ring while the other double bond was retained near the backbone without crosslinking. During the copolymerization of ethylene with ENB, a positive ‘comonomer effect’ was observed. The catalytic activities of the catalysts as well as the molecular weights and comonomer incorporations of the resultant copolymers could be tuned within a wide range by varying the structures of the catalysts and copolymerization conditions. The [ONN]-type oxovanadium(V) complexes showed higher catalytic activities than those of [ONNO]-type oxovanadium(V) complexes, irrespective of the structure of the dienes. In addition, the dominant chain transfer pathway of the non-metallocene oxovanadium(V) catalytic system promoted copolymerization was proven to be transfer to aluminum compounds. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Use of Vanadium Complexes Bearing Naphthalene-Bridged Nitrogen-Sulfonate Ligands as Catalysts for Copolymerization of Ethylene and Propylene
Polymers 2017, 9(8), 325; https://doi.org/10.3390/polym9080325
Received: 25 June 2017 / Revised: 19 July 2017 / Accepted: 24 July 2017 / Published: 31 July 2017
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Abstract
Vanadium complexes bearing naphthalene-bridged nitrogen-sulfonate ligand ([ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VOCl (1a) and [ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VCl2 (1b)) were synthesized. Activated by ethylaluminium sesquichloride (EASC) and in the presence of ethyl trichloroacetate (ETCA) as reactivator, complexes 1a and 1b showed activities
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Vanadium complexes bearing naphthalene-bridged nitrogen-sulfonate ligand ([ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VOCl (1a) and [ê2(N,O)-8-(PhN)-1-naphthalenesulfonato]VCl2 (1b)) were synthesized. Activated by ethylaluminium sesquichloride (EASC) and in the presence of ethyl trichloroacetate (ETCA) as reactivator, complexes 1a and 1b showed activities of up to 39.1 kg polymer (mol V)−1 h−1, affording the copolymers with high molecular weights (Mw up to 28 × 104) and narrow molecular weight distributions (Mw/Mn ~ 3.0) as well as high propylene incorporation of up to 49.4%. Compared to the traditional VOCl3 system, these complexes exhibited higher propylene incorporation ability and higher catalytic activities especially at high polymerization temperatures of 50 °C and above. Determined by DSC and 13C NMR, the copolymers obtained with 1a and 1b had more random structures than that with the VOCl3 system. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Homo- and Copolymerizations of Ethylene and Norbornene Using Bis(β-ketoamino) Titanium Catalysts Containing Pyrazolone Rings
Polymers 2017, 9(7), 262; https://doi.org/10.3390/polym9070262
Received: 14 June 2017 / Revised: 27 June 2017 / Accepted: 28 June 2017 / Published: 30 June 2017
Cited by 2 | PDF Full-text (1417 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (13) have been synthesized, characterized, and used as precursors for homo- and copolymerization of ethylene and norbornene. The titanium complexes activated with methylaluminoxane (MAO) exhibited good activities for homopolymerization of
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A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (13) have been synthesized, characterized, and used as precursors for homo- and copolymerization of ethylene and norbornene. The titanium complexes activated with methylaluminoxane (MAO) exhibited good activities for homopolymerization of ethylene (E) to produce linear polyethylenes (PEs). Ethylene–norbornene copolymers (E–N) were also prepared by these catalysts with moderate activities, and influences of ligand substituents and norbornene addition on copolymer microstructure were studied in detail. Microstructure analysis of the E–N copolymers by 13C NMR and differential scanning calorimetry (DSC) techniques showed that alternating (ENEN) and isolated (ENEE) norbornene predominately appeared in the copolymer chain, and the NN dyad and NNN triad sequences were also present in the copolymers obtained by the less bulky catalyst 1. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Isothermal and Non-Isothermal Crystallization Studies of Long Chain Branched Polypropylene Containing Poly(ethylene-co-octene) under Quiescent and Shear Conditions
Polymers 2017, 9(6), 236; https://doi.org/10.3390/polym9060236
Received: 26 May 2017 / Revised: 15 June 2017 / Accepted: 16 June 2017 / Published: 20 June 2017
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Abstract
Isothermal and non-isothermal crystallization behaviours of the blends of long chain branched polypropylene (LCB PP) and poly(ethylene-co-octene) (PEOc) with different weight ratios were studied under quiescent and shear flow using polarized optical microscopy (POM), differential scanning calorimetry (DSC), and rheological measurements.
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Isothermal and non-isothermal crystallization behaviours of the blends of long chain branched polypropylene (LCB PP) and poly(ethylene-co-octene) (PEOc) with different weight ratios were studied under quiescent and shear flow using polarized optical microscopy (POM), differential scanning calorimetry (DSC), and rheological measurements. Experimental results showed that the crystallization of the LCB PP/PEOc blends were significantly accelerated due to the existence of the long chain branches (LCBs), the blends being able to rapidly crystallize even at 146 °C. The addition of PEOc that acts as a nucleating agent, could also increase the crystallization rate of LCB PP. However, the crystallization rate of LCB PP was reduced when the PEOc concentration was more than 60 wt %, showing a retarded crystallization growth mechanism. The morphology of the binary blend was changed from a sea-island structure to a co-continuous phase structure when the PEOc concentration was increased from 40 to 60 wt %. In comparison with linear isotactic iPP/PEOc, the interfacial tension between LCB PP and PEOc was increased. In addition, flow-induced crystallization of LCB PP/PEOc blends was observed. Possible crystallization mechanisms for both LCB PP/PEOc and iPP/PEOc blends were proposed. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle Influence of Ligand Backbone Structure and Connectivity on the Properties of Phosphine-Sulfonate Pd(II)/Ni(II) Catalysts
Polymers 2017, 9(5), 168; https://doi.org/10.3390/polym9050168
Received: 1 April 2017 / Revised: 28 April 2017 / Accepted: 3 May 2017 / Published: 9 May 2017
Cited by 7 | PDF Full-text (3173 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Phosphine-sulfonate based palladium and nickel catalysts have been extensively studied in ethylene polymerization and copolymerization reactions. Previously, the majority of the research works focused on the modifications of the substituents on the phosphorous atom. In this contribution, we systematically demonstrated that the change
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Phosphine-sulfonate based palladium and nickel catalysts have been extensively studied in ethylene polymerization and copolymerization reactions. Previously, the majority of the research works focused on the modifications of the substituents on the phosphorous atom. In this contribution, we systematically demonstrated that the change of the ligand backbone from benzene to naphthalene could greatly improve the properties of this class of catalysts. In the palladium system, this change could increase catalyst stability and polyethylene molecular weights. In the nickel system, this change could dramatically increase the polyethylene molecular weights. Most interestingly, the change in the connectivity of phosphine and sulfonate moieties to the naphthalene backbone could also significantly influence the catalyst properties. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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Open AccessArticle A Modified Ceramic-Coating Separator with High-Temperature Stability for Lithium-Ion Battery
Polymers 2017, 9(5), 159; https://doi.org/10.3390/polym9050159
Received: 28 March 2017 / Revised: 24 April 2017 / Accepted: 25 April 2017 / Published: 29 April 2017
Cited by 7 | PDF Full-text (20523 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, the ceramic coating separator (CCS-CS) prepared with polyethylene (PE) separator, Al2O3 inorganic particles, carboxymethyl cellulose sodium (CMC) and styrene-butadiene rubber (SBR) mix binders is further modified by coating with a thin polydopamine (PDA) layer through a simple
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In this work, the ceramic coating separator (CCS-CS) prepared with polyethylene (PE) separator, Al2O3 inorganic particles, carboxymethyl cellulose sodium (CMC) and styrene-butadiene rubber (SBR) mix binders is further modified by coating with a thin polydopamine (PDA) layer through a simple chemical deposition method. Compared with the bare ceramic coating separator, the PDA-modified CCS-CS (CCS-CS-PDA) exhibits excellent thermal stability, which shows no thermal shrinkage after storing at 200 °C for 30 min. Compared with the PE separator, both the uptake and wettability with the electrolyte and water of CCS-CS-PDA are improved significantly. Meanwhile, when saturated with liquid electrolyte, the CCS-CS-PDA also shows enabled high ionic conductance. Furthermore, the test of the electrochemical impedances changing with the temperatures suggests that only the PE separator exhibits no thermal shutdown behaviors, and the CCS-CS separator only has a shutdown temperature range from 138 to 160 °C, while the CCS-CS-PDA shows a shutdown temperature range from 138 to more than 200 °C. The cells prepared with the CCS-CS-PDA also show stable repeated cycling performance and good rate capacity at room temperature. Full article
(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)
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