Higher Α-olefins Research Articles

Random and Block Copolymers of Isotactic Polypropylene with Higher α-Olefins: The Role of the Chain Topology on the Side-Chains Confined Crystallization

Random and Block Copolymers of Isotactic Polypropylene with Higher α-Olefins: The Role of the Chain Topology on the Side-Chains Confined Crystallization

Preparation of polybutene-based thermoplastic elastomers through the copolymerization of 1-butene with higher α-olefins

The comb-like structure composed of a crystalline main chain and an amorphous side chain endows the copolymers with both high strength and high toughness.

Effect of potassium on GO-modified large Fe3O4 microspheres for the production of α-olefins

Despite that iron-based catalysts are preferred for the high selectivity to value-added α-olefins via Fischer-Tropsch synthesis (FTS) reaction, the carbon deposition leads to deactivate catalyst more readily and CO2 selectivity as high as ~50% leads to low carbon efficiency. Herein, we developed an innovative approach to fabricate iron-based catalysts to deal with this issue. In detail, prepare Fe3O4 microsphere with an average particle size of ~580 nm via hydrothermal method and mix it with GO. The GO modification could effectively inhibit the sintering and coking of the large Fe3O4 microspheres (580 nm) by assisting its evolution into much smaller iron carbide nanocapsules (~9.1 nm). And the obtained catalyst exhibited excellent reaction activity, stability and high α-olefin selectivity. The addition of K into Fe3O4 microsphere produces major ɛ’-Fe2.2C about 58.9% in the evolution process and facilitates lower CO2 emission obviously.

Copolymerization of Propylene with Higher α-Olefins by a Pyridylamidohafnium Catalyst: An Effective Approach to Polypropylene-Based Elastomer.

In this contribution, we explored the copolymerization of propylene with higher α-olefins, including 1-octene (C8) 1-dodecene (C12), 1-hexadecene (C16) and 1-eicosene (C20), by using a dimethyl pyridylamidohafnium catalyst. A series of copolymers with varied comonomer incorporation, high molecular weight and narrow molecular weight distribution were obtained at mild conditions. The effects of the insertion of the comonomers on the microstructure, thermal and final mechanical properties were systemically studied by 13C NMR, wide-angle X-ray scattering, DSC and tensile test. Excellent mechanical performances were achieved by tuning the incorporation and chain length of the higher α-olefins. When the comonomer content reached above 12 mol.%, polypropylene-based elastomers were obtained with high ductility. A combination of excellent elastic recovery and flexibility was achieved for the P/C16 copolymers with about 20 mol.% monomer incorporation. The monomer incorporation and side chain length played a crucial role in determining the mechanical property of the outstanding polypropylene-based elastomers.

Structural evolution of large Fe3O4microspheres on graphene oxide for efficient conversion of syngas into α-olefins

Large porous Fe3O4microspheres on graphene oxide under FTS reaction conditions can evolve into much smaller iron carbide nanocapsules, which show excellent and stable activity and high α-olefin productivity.

Optimization of Process Parameters for the Nitration Reaction of Long-Chain Linear α-Olefins in Polar and Nonpolar Solvents

Statistical processing of experimental data to reveal the optimal conditions for nitration of higher linear α-olefins with nitrogen oxide in polar and nonpolar solvent media has been carried out. The influence of various factors (temperature, time, reactant feed rate) on the yield and composition of nitro products has been shown.

Bis-salicyladenimine fluorine-containing titanium(+4) complexes in polymerization of higher α-olefins

Bis-salicyladenimine fluorine-containing titanium(+4) complexes in polymerization of higher α-olefins

Preparation of Novel Quaternary Plastomers with Extremely Low Glass Transition Temperature

In this study, novel quaternary plastomers consisting of ethylene, 1-hexene, high α-olefin, and divinylbenzene were prepared using Zr metallocene catalyst, borate type cocatalyst, and tri-isobutylaluminium. The molar ratio changes of 1-hexene and high α-olefin (1-octene, 1-decene, and 1-dodecene) had an effect on the properties of the quaternary plastomers. The structure of the quaternary plastomers was characterized using 1H NMR. Molecular weight properties, crystallinity, and thermal properties of the plastomers were determined by GPC, WAXS, and DMA, respectively. Compared with the terpolymers prepared in our previous study, molecular weight and molecular weight distribution of the quaternary polymers were very similar, whereas glass transition temperature (Tg) was very low. Also, hardness and tensile properties of the quaternary plastomers were measured.

Osmium(0)-Catalyzed C-C Coupling of Ethylene and α-Olefins with Diols, Ketols, or Hydroxy Esters via Transfer Hydrogenation.

Osmium(0) complexes derived from Os3(CO)12 and XPhos (2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) catalyze the C-C coupling of α-hydroxy esters 1a-1i, α-ketols 1j-1o, or 1,2-diols dihydro-1j-1o with ethylene 2a to form ethylated tertiary alcohols 3a-3o. As illustrated in couplings of 1-octene 2b with vicinally dioxygenated reactants 1a, 1b, 1i, 1j, 1k, 1m, higher α-olefins are converted to adducts 4a, 4b, 4i, 4j, 4k, 4m with complete levels of branched regioselectivity. Oxidation level independent C-C coupling is demonstrated by the reaction of 1-octene 2b with diol dihydro-1k, α-ketol 1k, and dione dehydro-1k. Functionalized olefins 2c-2f react with ethyl mandelate 1a to furnish adducts 5a-8a as single regioisomers. The collective data, including deuterium labeling studies, are consistent with a catalytic mechanism involving olefin-dione oxidative coupling to form an oxa-osmacyclopentane, which upon reductive cleavage via hydrogen transfer from the secondary alcohol reactant releases the product of carbinol C-alkylation with regeneration of the ketone. Single-crystal X-ray diffraction data of the dinuclear complex Os2(CO)4(O2CR)2(XPhos)2 and the trinuclear complex Os3(CO)11(XPhos) are reported. These studies suggest increased π-backbonding at the stage of the metal-olefin π-complex plays a critical role in facilitating alkene-carbonyl oxidative coupling, as isostructural ruthenium(0) complexes, which are weaker π-donors, do not catalyze the transformations reported herein.

Modulating Polyolefin Copolymer Composition via Redox-Active Olefin Polymerization Catalysts.

The ability to precisely modulate polymer architecture and composition is a long-standing goal within the field of polymer synthesis. Herein, we demonstrate that redox-active olefin polymerization catalysts may be used to predictably tailor polyolefin comonomer incorporation levels for the copolymerization of ethylene and higher α-olefins. This ability is facilitated via the utilization of a redox-active olefin polymerization catalyst that once reduced via in situ addition of a chemical reductant results in a notable drop in α-olefin incorporation. We attribute this behavior to the reduced catalyst's increased electron density and its concomitant decreased rate of α-olefin consumption. These results are supported by investigations into propylene and 1-hexene homopolymerizations as well as detailed GPC, DSC, GC, and NMR analyses.

Theoretical investigation of the mechanism of ethylene polymerization with salicylaldiminato vanadium(III) complexes

The use of vanadium-based catalysts allows the preparation of high molecular mass polymers with uniform molecular mass distributions, polypropylene and ethylene/α-olefin copolymers with high α-olefin incorporation. However, the design of ligand systems with vanadium catalysts would face difficulties, because it is difficult to experimentally determine the structures of the active species of vanadium catalysts. In this paper, possible structural candidates for the active species in ethylene polymerization catalyzed by the salicylaldiminato vanadium complex combined with AlEt2Cl were investigated using density functional theory. By comparing theoretical simulation results with previous experimental investigations, especially regarding the crucial role of the diethyaluminum chloride (AlEt2Cl) cocatalyst, it was concluded that a neutral bimetallic species containing two Al–Cl–V bridging bonds is the most favorable structure model for the active vanadium species. A notable effect of Al co-catalysts was clarified in the theoretical investigation. During the formation of the active species, AlEt2Cl act as an assistant for the alkylation and alkyl abstract processes of precursors. More importantly, AlEt2Cl is necessary for the formation of the bis(chlorine-bridged) structure in the active species, which showed a notable effect on the structural stability of the active species and its catalytic activity. Additionally, we investigated the chain termination mechanism in this system.

Titanium Complex Containing a Saligenin Ligand - New Universal Post-Metallocene Polymerization Catalyst: Copolymerization of Ethylene with Higher α-Olefins

Copolymerization reactions of ethylene with three α-olefins, 1-hexene, 1-octene and 1-decene, were carried out with a new post-metallocene catalyst based on Ti complex with a bidentate saligenin-type ligand I and two co catalysts, MAO and a combination of AlEt2Cl and MgBu2. Ability of the I - AlEt2Cl - MgBu2 system to copolymerize α-olefins with ethylene is far superior to that of the I - MAO system. Reactivity of α-olefins in copolymerization reactions with ethylene decreases in the sequence: 1-hexene>1-octene>1-decene. Both catalyst systems, I - MAO and I - AlEt2Cl - MgBu2, contain several populations of active centers that greatly differs both in the average molecular weights and in composition of the copolymer molecules they produce. Active centers in both catalytic systems show significant tendency to alternate monomer units in copolymer chains.

Metallocene-catalyzed oligomerizations of 1-butene and α-olefins: Toward synthetic lubricants

In this study we found that the oligomerizations of 1-butene with various higher α-olefins (1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene) in the presence of the catalyst (Me4Cp)2ZrCl2 and the co-catalyst methylaluminoxane yielded low-molecular-weight oily oligomers. 1H and 13C NMR spectroscopy revealed that the major olefinic bonds of these oligomers were terminal vinylidene and internal trisubstituted vinylidene units. The chain termination of oligomerization of 1-butene alone favored chain transfer to the co-catalyst, which process was favored after adding α-olefin and affected only slightly by the lateral size of the α-olefin. The addition of the α-olefin to 1-butene decreased the oligomerization activity, oligomer molecular weight and kinematic viscosity, but increased oligomer viscosity index. Moreover, the oligomerization activity, oligomer molecular weight and kinematic viscosity were presented as a function of the concentration of α-olefin, the oligomerization temperature and the Al/Zr ratio.

Oligomerization of higher α-olefins over catalysts containing an F-4SF perfluorinated copolymer

The oligomerization of higher α-olefins over a set of heterogeneous mesoporous catalysts has been studied using the example of decene-1. It has been shown that mesoporous catalysts based on the sulfonated, perfluorinated copolymer F-4SF exhibit high activity in oligomerization of decene-1 in both a batch reactor and a flow system: in the former case, the olefin conversion reaches 95–99% with the yield of dimers of 90–95%; in the latter case, the conversion of decene-1 to oligomers exceeds 70%.

Synthesis and Characterization of Well-Controlled Isotactic Polypropylene Ionomers Containing Ammonium Ion Groups

This paper discusses the synthesis of a new family of well-controlled isotactic polypropylene ionomers (iPP-NH3+Cl–) containing up to 5 mol % of NH3+Cl– ionic groups, with high molecular weight and narrow molecular weight and composition distributions, as well as good processability in melt and solution. A systematic study was conducted using various isospecific Ziegler–Natta and metallocene catalysts in the copolymerization of propylene and a high α-olefin comonomer containing a silane-protected amino group and the subsequent work-up procedures that can prevent undesirable side reactions in forming iPP-NH3+Cl– ionomers in a one-pot process. The resulting copolymers were carefully monitored by polymer solubility and a combination of NMR, GPC-triple detectors, DSC, and mechanical property measurements. Evidently, the most suitable reaction process requires a combination of the rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2 metallocene catalyst system with a purified d-MAO (TMA-free), 6-bis(trimethylsilyl)amino-1-hexene comonomer during the copolymerization reaction and a work-up procedure to directly interconvert the silane-protected amino groups (−N(SiMe3)2) into −NH3+Cl– ionic groups before exposing to air. The attempt of isolating both iPP-N(SiMe3)2 and iPP-NH2 intermediates resulted in the insoluble (cross-linked) products. On the other hand, the resulting iPP-NH3+Cl– ionomers were melt processed in air and showed a systematic increase of mechanical properties and high-temperature stability with the increase of NH3+Cl– content.

도입된 High α-olefin의 사슬길이 변화에 따른 삼원공중합체 특성 변화

본 연구에서는 여러가지 메탈로센 촉매 및 trityl tetrakis(pentafluorophenyl)borate/triisobutylaluminium 공촉매 시스템을 이용하여 에틸렌, high <TEX>${\alpha}$</TEX>-olefin 및 divinylbenzene으로 구성된 삼원공중합체를 중합하였다. 우선 삼원공중합체 중합에 있어서, 최적의 촉매를 확보하기 위해 rac-<TEX>$Et(Ind)_2ZrCl_2$</TEX>, rac-<TEX>$SiMe_2(Ind)_2ZrCl_2$</TEX>, rac-<TEX>$SiMe_2(2-Me-Ind)_2ZrCl_2$</TEX> 등의 메탈로센 촉매들과 trityl tetrakis(pentafluorophenyl)borate/triisobutylaluminium 공촉매 시스템을 이용하여 삼원공중합체의 촉매활성도, 분자량 및 분자량 분포도를 비교하였다. 공단량체로 투입되는 high <TEX>${\alpha}$</TEX>-olefin의 사슬 길이 변화가 삼원공중합에 미치는 영향을 살펴보기 위해 여러 가지 중합 조건들은 동일하게 유지하면서 1-hexene, 1-octene, 1-decene 또는 1-dodecene을 도입한 삼원공중합체들을 각각 합성하였다. 이와 같이 준비한 삼원공중합체들의 화학 조성, 열적 특성 및 기계적 물성 등을 비교 분석하였다. In this study, we prepared poly(ethylene-ter-1-hexene-ter-divinylbenzene) using various metallocene catalysts with trityl tetrakis(pentafluorophenyl)borate/triisobutylaluminium cocatalysts system. We tried rac-<TEX>$Et(Ind)_2ZrCl_2$</TEX>, rac-<TEX>$SiMe_2(Ind)_2ZrCl_2$</TEX>, and rac-<TEX>$SiMe_2(2-Me-Ind)_2ZrCl_2$</TEX> to choose optimum metallocene catalyst, comparing with catalytic activity, molecular weight, molecular weight distribution of the terpolymers. To study the effects of chain length of high <TEX>${\alpha}$</TEX>-olefins on the terpolymerization, we synthesized the terpolymers using 1-hexene, 1-octene, 1-decene or 1-dodecene. We characterized chemical composition, thermal properties, and mechanical properties of the terpolymers.

Pt-catalysed intermolecular hydroamination of non-activated olefins using a novel family of catalysts: Arbuzov-type phosphorus metal complexes

The catalytic system “PtBr2(0.3mol%)/2P(OR)3/10nBu4PBr” (R=alkyl) discovered recently in our group, allows good to excellent catalytic activities for the intermolecular hydroamination of ethylene and higher α-olefins (1-hexene) with aniline type amines to give the expected N-ethyl- (1) and N,N-diethyl-anilines (2) along with 2-methyl-quinoline (3). A poisoning effect of alkyl and aromatic phosphines has been observed. This effect could be minimised using small amounts of molecular iodide which reacts with phosphorus ligands to form non-coordinating well-described ionic species. Interestingly, beneficial effects of added P(OR)3 (R=alkyl) have been pointed out and further investigated. In this way, a new potential family of Arbuzov-type phosphorus-metal complexes has been suggested to be responsible for good catalytic activities found when using P(OR)3 alkyl phosphites rather than PR3 (R=alkyl, aromatic) and P(OPh)3 co-catalysts. [Display omitted]

Novel Effectively Carbonaceous and Sulfurated Hydrogen Corrosion Inhibitors on the Basis of Organosulfurphosphorus Compounds

Novel ammonium salts of O,O-dialkyl dithiophosphoric acids were obtained by one-pot synthesis from white phosphorus, elemental sulfur, industrial alcohols or phenols, and amines. Long-chain S-alkyl O,O-dialkyldithiophosphonates were prepared by the reaction of red phosphorus with elemental sulfur, alcohols, and the cheap industrial fractions of С16–С18 and С20–С26 of higher α-olefins in the presence of Lewis acid catalyst. The dithiophosphates obtained possess the high anticorrosion activities toward mild steel.

Effect of comonomer partitioning on the kinetics of mesophase formation in random copolymers of propene and higher α-olefins

The effect of counit type on the kinetics of mesophase formation has been investigated by means of chip-calorimetry in propene/α-olefin random copolymers, containing counits which show large differences in their co-crystallization behavior with propene, i.e. 1-butene and 1-hexene. Non-isothermal crystallization experiments indicated that the minimum cooling rate at which mesophase formation is observed is directly related to the kinetic of α-phase crystallization, which is lower for the copolymer with the bulkier 1-hexene counit. Isothermal structuring was probed in a wide temperature range, revealing that a double bell-shaped curve is required to describe the temperature dependence of crystallization times of the two polymorphs. The ordering kinetics of the mesophase is the fastest in i-PP homopolymer and decreases with increasing comonomer bulkiness, analogous to what happens for the monoclinic phase. The results are discussed by considering the effect of comonomer on the driving force for mesophase formation, also at the light of new WAXD and density evidences, which prove different extents of inclusion of 1-butene and 1-hexene in the ordered phases.

Synthesis and Characterization of Complex Macromolecular Architectures Based on Poly(α-olefins) Utilizing a Cs-Symmetry Hafnium Metallocene Catalyst in Combination with Atom Transfer Radical Polymerization (ATRP)

Herein we describe the synthesis of block and graft copolymers made from several higher α-olefins, and in some cases styrene and methyl methacrylate, through the use of metallocene catalysts as wel...