Ethylene–propylene copolymerization and their terpolymerization with dienes using <i>ansa</i>-Zirconocene catalysts activated by borate/alkylaluminum

Ali, Amjad; Akram, Muhammad; Guo, Yintian; Wu, Haifeng; Liu, Wucan; Khan, Abid; Liu, Xiaoyu; Fu, Zhisheng; Fan, Zhiqiang

doi:10.1080/10601325.2019.1674667

Cited by 21 publications

(36 citation statements)

References 39 publications

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“…Similar phenomena were observed for the ethylene‒propylene copolymerization. Numerous reasons have been given in the literature to explain the increase in catalytic activity with low comonomer concentrations, such as the ethylene homopolymer’s low solubility compared to the ethylene copolymer, which helps with monomer diffusion to the active center [ 26 , 44 ]. Moreover, the comonomer plays a role in the activation of new catalyst active sites and increases the E insertion rate.…”

Section: Resultsmentioning

confidence: 99%

Comparative Analysis of Ethylene/Diene Copolymerization and Ethylene/Propylene/Diene Terpolymerization Using Ansa-Zirconocene Catalyst with Alkylaluminum/Borate Activator: The Effect of Conjugated and Nonconjugated Dienes on Catalytic Behavior and Polymer Microstructure

et al. 2021

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The copolymerization of ethylene‒diene conjugates (butadiene (BD), isoprene (IP) and nonconjugates (5-ethylidene-2-norbornene (ENB), vinyl norbornene VNB, 4-vinylcyclohexene (VCH) and 1, 4-hexadiene (HD)), and terpolymerization of ethylene-propylene-diene conjugates (BD, IP) and nonconjugates (ENB, VNB, VCH and HD) using two traditional catalysts of C2-symmetric metallocene—silylene-bridged rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (complex A) and ethylene-bridged rac-Et(Ind)2ZrCl2 (complex B)—with a [Ph3C][B(C6F5)4] borate/TIBA co-catalyst, were intensively studied. Compared to that in the copolymerization of ethylene diene, the catalytic activity was more significant in E/P/diene terpolymerization. We obtained a maximum yield of both metallocene catalysts with conjugated diene between 3.00 × 106 g/molMt h and 5.00 × 106 g/molMt h. ENB had the highest deactivation impact on complex A, and HD had the most substantial deactivation effect on complex B. A 1H NMR study suggests that dienes were incorporated into the co/ter polymers’ backbone through regioselectivity. ENB and VNB, inserted by the edo double bond, left the ethylidene double bond intact, so VCH had an exo double bond. Complex A’s methyl and phenyl groups rendered it structurally stable and exhibited a dihedral angle greater than that of complex B, resulting in 1,2 isoprene insertion higher than 1, 4 isoprene that is usually incapable of polymerization coordination. High efficiency in terms of co- and ter- monomer incorporation with higher molecular weight was found for complex 1. The rate of incorporation of ethylene and propylene in the terpolymer backbone structure may also be altered by the conjugated and nonconjugated dienes. 13C-NMR, 1H-NMR, and GPC techniques were used to characterize the polymers obtained.

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Section: Resultsmentioning

confidence: 99%

Comparative Analysis of Ethylene/Diene Copolymerization and Ethylene/Propylene/Diene Terpolymerization Using Ansa-Zirconocene Catalyst with Alkylaluminum/Borate Activator: The Effect of Conjugated and Nonconjugated Dienes on Catalytic Behavior and Polymer Microstructure

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“…Obtained polymers products were characterized by high temperature (120 °C) nuclear magnetic resonance spectroscopy ( 1 H-NMR and 13 C-NMR) using instrument Varian Mercury-300 spectrometer (Hangzhou, China) operating 75 MHz within acquisition time 3.0 s. To obtai 13 C-NMR spectra for quantitative determination, the estimated amount (2–3 mg) of relaxation agent Cr(acac) 3 was added to the sample tube, and 1,1,2,2-tetrachloroethane-d 2 was used as the solvent for NMR analysis at 120 °C [ 45 , 46 , 47 ].…”

Section: Methodsmentioning

confidence: 99%

Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

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The kinetics of ethylene and propylene polymerization catalyzed by homogeneous metallocene were investigated using 2-thiophenecarbonyl chloride followed by quenched-flow methods. The studied metallocene catalysts are: rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (Mt-I), rac-Et(Ind)2ZrCl2 (Mt-II) activated with ([Me2NPh][B(C6F5)4] (Borate-I), [Ph3C][B(C6F5)4] (Borate-II), and were co-catalyzed with different molar ratios of alkylaluminum such as triethylaluminium (TEA) and triisobutylaluminium (TIBA). The change in molecular weight, molecular weight distribution, microstructure and thermal properties of the synthesized polymer are discussed in detail. Interestingly, both Mt-I and Mt-II showed high activity in polyethylene with productivities between 3.17 × 106 g/molMt·h to 5.06 × 106 g/molMt·h, activities were very close to each other with 100% TIBA, but Mt-II/borate-II became more active when TEA was more than 50% in cocatalyst. Similarly, Polypropylene showed the highest activity of 11.07 106 g /molMt·h with Mt-I/Borate-I/TIBA. The effects of alkylaluminum on PE molecular weight were much more complicated; MWD curve changed from mono-modal in Mt-I/borate-I/TIBA to bimodal type when TIBA was replaced by different amounts of TEA. In PE, the active center fractions [C*]/[Zr] of Mt-I/borate were higher than that of Mt-II/borate and average chain propagation rate constant (kp) value slightly decreased with the increase of TEA/TIBA ratio, but the Mt-II/borate systems showed higher kp 1007 kp (L/mol·s). In PP, the Mt-I/borate presented much higher [C*]/[Zr] and kp value than the Mt-II. This work also extend to investigate the mechanistic features of zirconocenes catalyzed olefin polymerizations that addressed the largely unknown issues in zirconocenes in the distribution of the catalyst, between species involved in polymer chain growth and dormant state. In both metallocene systems, chain transfer with alkylaluminum is the dominant way of chain termination. To understand the mechanism of cocatalyst effects on PE Mw and (MWD), the unsaturated chain ends formed via β-H transfer have been investigated by 1H NMR analysis.

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“…The solvent was odichlorobenzene-d 4 , and the polymer solution had a concentration of 10% by weight. Hexamethyldisiloxane was used as an internal chemical shi reference in the spectra, which were recorded at 120 C. To decrease the relaxation period of the carbon atoms, Cr(acac) 3 was added, and the pulse delay time was adjusted to 3 s. 11,12 The pulse was at a 90 angle, the acquisition took 0.8 seconds, and 8000 Hz was the spectral breadth. For integration, inverse gated decoupling was used.…”

Section: Characterizationmentioning

confidence: 99%

“…[5][6][7][8][9] Cyclic norbornene (NB) and its derivatives (ENB and VNB) have a ring strain in their structure and are easily polymerized via cationic, radical, and vinyl-type addition. [10][11][12] Cyclic di-olens prepared via vinyl-type addition show superior properties such as excellent optical transparency, chemical resistance, moisture absorption, and low birefringence. 11,13 Because of their outstanding transparency and excellent chemical and thermal stability compared to PE and polypropylene (PP), ethylene/a-olen copolymers and cyclic olen copolymers (COCs) are suitable choices for optical devices and engineering plastics.…”

Section: Introductionmentioning

confidence: 99%

Rapid kinetic evaluation of homogeneous single-site metallocene catalysts and cyclic diene: how do the catalytic activity, molecular weight, and diene incorporation rate of olefins affect each other?

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Ethylene–propylene copolymerization and their terpolymerization with dienes using ansa-Zirconocene catalysts activated by borate/alkylaluminum

Cited by 21 publications

References 39 publications

Comparative Analysis of Ethylene/Diene Copolymerization and Ethylene/Propylene/Diene Terpolymerization Using Ansa-Zirconocene Catalyst with Alkylaluminum/Borate Activator: The Effect of Conjugated and Nonconjugated Dienes on Catalytic Behavior and Polymer Microstructure

Comparative Analysis of Ethylene/Diene Copolymerization and Ethylene/Propylene/Diene Terpolymerization Using Ansa-Zirconocene Catalyst with Alkylaluminum/Borate Activator: The Effect of Conjugated and Nonconjugated Dienes on Catalytic Behavior and Polymer Microstructure

Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

Rapid kinetic evaluation of homogeneous single-site metallocene catalysts and cyclic diene: how do the catalytic activity, molecular weight, and diene incorporation rate of olefins affect each other?

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