Research

12 pages, 1853 KiB

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

by Olga A. Serenko, Mikhail I. Buzin, Vladislav A. Tuskaev, Svetlana C. Gagieva, Nikolay A. Kolosov, Dmitrii A. Kurmaev, Tatyana F. Savel’eva, Evgenii K. Golubev, Sergey V. Zubkevich, Viktor G. Vasil’ev, Galina G. Nikiforova, Alexander A. Korlyukov and Boris M. Bulychev

Polymers 2018, 10(11), 1281; https://doi.org/10.3390/polym10111281 - 17 Nov 2018

Cited by 7 | Viewed by 4041

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 (T_poly) 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 T_poly, 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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19 pages, 4310 KiB

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

by Elise Vanbiervliet, Stéphane Fouquay, Guillaume Michaud, Frédéric Simon, Jean-François Carpentier and Sophie M. Guillaume

Polymers 2018, 10(11), 1241; https://doi.org/10.3390/polym10111241 - 09 Nov 2018

Cited by 8 | Viewed by 5577

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 (NB^COOMe), 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 -NB^COOMe)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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15 pages, 2964 KiB

Open AccessArticle

Influences of Fluorine Substituents on Iminopyridine Fe(II)- and Co(II)-Catalyzed Isoprene Polymerization

by Guangqian Zhu, Xianhui Zhang, Mengmeng Zhao, Liang Wang, Chuyang Jing, Peng Wang, Xiaowu Wang and Qinggang Wang

Polymers 2018, 10(9), 934; https://doi.org/10.3390/polym10090934 - 22 Aug 2018

Cited by 31 | Viewed by 5390

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 (M_n = 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 (M_n < 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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19 pages, 4860 KiB

Open AccessArticle

Multi-Alkenylsilsesquioxanes as Comonomers and Active Species Modifiers of Metallocene Catalyst in Copolymerization with Ethylene

by Paweł Groch, Katarzyna Dziubek, Krystyna Czaja, Katarzyna Mituła and Beata Dudziec

Polymers 2018, 10(2), 223; https://doi.org/10.3390/polym10020223 - 24 Feb 2018

Cited by 9 | Viewed by 4737

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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13 pages, 3896 KiB

Open AccessArticle

The Dispersion of Pulp-Fiber in High-Density Polyethylene via Different Fabrication Processes

by Xiaohui Yang, Guangzhao Wang, Menghe Miao, Jinquan Yue, Jianxiu Hao and Weihong Wang

Polymers 2018, 10(2), 122; https://doi.org/10.3390/polym10020122 - 26 Jan 2018

Cited by 8 | Viewed by 4967

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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9 pages, 1171 KiB

Open AccessArticle

High Temperature, Living Polymerization of Ethylene by a Sterically-Demanding Nickel(II) α-Diimine Catalyst

by Lauren A. Brown, W. Curtis Anderson, Nolan E. Mitchell, Kevin R. Gmernicki and Brian K. Long

Polymers 2018, 10(1), 41; https://doi.org/10.3390/polym10010041 - 02 Jan 2018

Cited by 29 | Viewed by 5192

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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4526 KiB

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

by Vladislav A. Tuskaev, Svetlana C. Gagieva, Dmitrii A. Kurmaev, Nikolay A. Kolosov, Elena S. Mikhaylik, Evgenii K. Golubev, Alexander I. Sizov, Sergey V. Zubkevich, Viktor G. Vasil’ev, Galina G. Nikiforova, Mikhail I. Buzin, Olga A. Serenko and Boris M. Bulychev

Polymers 2018, 10(1), 2; https://doi.org/10.3390/polym10010002 - 21 Dec 2017

Cited by 13 | Viewed by 5394

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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739 KiB

Open AccessArticle

Substituent Effects of Adamantyl Group on Amido Ligand in Syndiospecific Polymerization of Propylene with Ansa-Dimethylsilylene(Fluorenyl)(Amido) Zirconium Complex

by Yanjie Sun, Shuhui Li, Takeshi Shiono and Zhengguo Cai

Polymers 2017, 9(11), 632; https://doi.org/10.3390/polym9110632 - 21 Nov 2017

Cited by 2 | Viewed by 4038

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 C_s-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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3446 KiB

Open AccessArticle

The Dynamic Mechanical Analysis of Highly Filled Rice Husk Biochar/High-Density Polyethylene Composites

by Qingfa Zhang, Hongzhen Cai, Xueyong Ren, Lingshuai Kong, Jianbiao Liu and Xuya Jiang

Polymers 2017, 9(11), 628; https://doi.org/10.3390/polym9110628 - 17 Nov 2017

Cited by 45 | Viewed by 6418

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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2278 KiB

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

by Xiaopeng Cui, Qing Bai, Kai Ma, Min Yang and Binyuan Liu

Polymers 2017, 9(11), 627; https://doi.org/10.3390/polym9110627 - 17 Nov 2017

Cited by 2 | Viewed by 6237

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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4132 KiB

Open AccessArticle

Propene Polymerization with C₁-Symmetric Fluorenyl-Metallocene Catalysts

by Laura Boggioni, Massimiliano Cornelio, Simona Losio, Abbas Razavi and Incoronata Tritto

Polymers 2017, 9(11), 581; https://doi.org/10.3390/polym9110581 - 06 Nov 2017

Cited by 7 | Viewed by 6364

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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2098 KiB

Open AccessArticle

Cis-1,4-Polymerization of Isoprene by 1,3-Bis(oxazolinymethylidene)isoindoline-Ligated Rare-Earth Metal Dialkyl Complexes

by Chao Yu, Dahai Zhou, Xiangqian Yan, Fei Gao, Li Zhang, Shaowen Zhang and Xiaofang Li

Polymers 2017, 9(10), 531; https://doi.org/10.3390/polym9100531 - 20 Oct 2017

Cited by 12 | Viewed by 5272

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)/(mol_Ln 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 (M_n of up to 710,000 g/mol) and bimodal molecular weight distributions (M_w/M_n = 2.0–4.5). Full article

(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)

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2892 KiB

Open AccessArticle

A Single-Site Iron(III)-Salan Catalyst for Converting COS to Sulfur-Containing Polymers

by Ge-Ge Gu, Tian-Jun Yue, Zhao-Qian Wan, Rong Zhang, Xiao-Bing Lu and Wei-Min Ren

Polymers 2017, 9(10), 515; https://doi.org/10.3390/polym9100515 - 17 Oct 2017

Cited by 18 | Viewed by 5076

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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3599 KiB

Open AccessArticle

Preparation of Isotactic Polypropylene/Exfoliated MoS₂ Nanocomposites via In Situ Intercalative Polymerization

by He-Xin Zhang, Xue-Quan Zhang and Keun-Byoung Yoon

Polymers 2017, 9(10), 490; https://doi.org/10.3390/polym9100490 - 07 Oct 2017

Cited by 11 | Viewed by 5568

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 T_d_5% 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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2060 KiB

Open AccessArticle

Polystyrene Chain Growth from Di-End-Functional Polyolefins for Polystyrene-Polyolefin-Polystyrene Block Copolymers

by Chung Sol Kim, Seung Soo Park, Sung Dong Kim, Su Jin Kwon, Jun Won Baek and Bun Yeoul Lee

Polymers 2017, 9(10), 481; https://doi.org/10.3390/polym9100481 - 02 Oct 2017

Cited by 12 | Viewed by 8299

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- [...] Read more.

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 (ΔM_n = 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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2200 KiB

Open AccessArticle

Facile, Efficient Copolymerization of Ethylene with Norbornene-Containing Dienes Promoted by Single Site Non-Metallocene Oxovanadium(V) Catalytic System

by Kaiti Wang, Jiabao Wang, Yanguo Li, Li Pan and Yuesheng Li

Polymers 2017, 9(8), 353; https://doi.org/10.3390/polym9080353 - 11 Aug 2017

Cited by 7 | Viewed by 5637

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 [...] Read more.

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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Use of Vanadium Complexes Bearing Naphthalene-Bridged Nitrogen-Sulfonate Ligands as Catalysts for Copolymerization of Ethylene and Propylene

by Xiufeng Hao, Chundi Zhang, Lin Li, Hexin Zhang, Yanming Hu, Daifeng Hao and Xuequan Zhang

Polymers 2017, 9(8), 325; https://doi.org/10.3390/polym9080325 - 31 Jul 2017

Cited by 16 | Viewed by 5431

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 [...] Read more.

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 (M_w up to 28 × 10⁴) and narrow molecular weight distributions (M_w/M_n ~ 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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1417 KiB

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Homo- and Copolymerizations of Ethylene and Norbornene Using Bis(β-ketoamino) Titanium Catalysts Containing Pyrazolone Rings

by Lixia Pei, San He, Jie Gao, Heng Liao and Haiyang Gao

Polymers 2017, 9(7), 262; https://doi.org/10.3390/polym9070262 - 30 Jun 2017

Cited by 11 | Viewed by 4977

Abstract

A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (1–3) 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 [...] Read more.

A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (1–3) 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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Isothermal and Non-Isothermal Crystallization Studies of Long Chain Branched Polypropylene Containing Poly(ethylene-co-octene) under Quiescent and Shear Conditions

by Zinan Zhang, Fengyuan Yu and Hongbin Zhang

Polymers 2017, 9(6), 236; https://doi.org/10.3390/polym9060236 - 20 Jun 2017

Cited by 13 | Viewed by 6424

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. [...] Read more.

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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3173 KiB

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Influence of Ligand Backbone Structure and Connectivity on the Properties of Phosphine-Sulfonate Pd(II)/Ni(II) Catalysts

by Zixia Wu, Changwen Hong, Hongxu Du, Wenmin Pang and Changle Chen

Polymers 2017, 9(5), 168; https://doi.org/10.3390/polym9050168 - 09 May 2017

Cited by 26 | Viewed by 6425

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 [...] Read more.

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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20523 KiB

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A Modified Ceramic-Coating Separator with High-Temperature Stability for Lithium-Ion Battery

by Chuan Shi, Jianhui Dai, Chao Li, Xiu Shen, Longqing Peng, Peng Zhang, Dezhi Wu, Daoheng Sun and Jinbao Zhao

Polymers 2017, 9(5), 159; https://doi.org/10.3390/polym9050159 - 29 Apr 2017

Cited by 62 | Viewed by 12555

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 [...] Read more.

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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