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In this contribution, we describe the kinetics associated with the rac-Me2Si[2-Me-4-Ph-Ind]2ZrCl2 (Cat-1)/borate/TIBA catalyzed copolymerization of E/dienes (isoprene (IP), butadiene (BD), 5-ethylidene-2-norbornene (ENB), 4-vinylcyclohexene (VCH) and vinyl norbornene (VNB)), and E/diene/1-hexene (1H) terpolymerization by using thiophenecarbonyl chloride (TPCC) that was used in Ziegler-Natta (Z-N) and metallocene-catalyzed polyethylene (PE) and polypropylene (PP) and E/P polymerizations. In both types of polymerizations, a higher amount of dienes was incorporated when VNB (2.70 mole %) and VCH (1.56 mole %) were added as comonomer, but IP and BD were incorporated with the moderated rate (0.6-1.1 mole %) with higher activities (3.45x106gm/mmolMt·h). The active center [Zr]/[C*] fraction is higher (61%) than previously reported PE polymerizations, especially in the case of E/IP, E/BD and E/IP/1H but lower than E/P (87%) copolymerization. Significantly, IP and BD activated the inactive catalytic sites that were dormant in the PE. The propagation rate constant (kpE) with IP was higher (kp564 Lmol-1s-1), while kpE with VNB (kp379 Lmol-1s-1) and VCH (kp304 Lmol-1s-1), which were lower than PE. This difference is built because of the diffusion barrier in the system. Compared to E/diene copolymers, kpE values in E/diene/1H terpolymerizations for IP, VCH, and VNB are higher and stable except ENB and determine that 1H prevents the insertion of dienes and reduces the crystalline properties resultant moderate kpE. Even though the E/BD copolymers decreased butadiene content of over 2 mol% resulted in better crystalline characteristics, lower diffusion barriers, and a higher kpE value. In concept, IP and BD are linear and readily available for coordination. While VCH, ENB and VNB are cyclic and bulky, metallocene in contact ion pairs cannot accept ENB, VNB, and VCH for coordination and subsequently act as dormant in the polymerization. [ABSTRACT FROM AUTHOR]

The objectives of this work were to address the fundamental characteristics of ansa-zirconocene catalyzed E/diene copolymerization and E/diene/1-hexene and E/diene/propylene terpolymerizations, and the quantitative relationship between diene structure and polymer chain propagation rate constant in term of quantifiable catalytic active sites. One of the most important but unknown factors in olefins ansa-zirconocene complexes is the distribution of the catalyst between sites actively participating in polymer chain formation and dormant sites. A set of ethylene/dienes copolymerizations, and ethylene/dienes/1-hexene and ethylene/dienes/1-hexene terpolymerizations catalyzed with ansa-zirconocenes/borate/triisobutylaluminium (rac-Et(Ind)2ZrCl2/[Ph3C][B(C6F5)4]/triisobutylaluminium (TIBA) were performed in toluene at 50 °C To determine the active center [C*]/[Zr] ratio variation in the copolymerization of E with different dienes and their terpolymerization with 1-hexene and propylene, each polymer propagation chain ends were quenched with 2-thiophenecarbonyl, which selectively quenches the metal–polymer bonds through acyl chloride. The ethylene, propylene, 1-hexene, and diene composition-based propagation rate constants (kpE, kpP, kp1-H, and kpdiene), thermal (melting and crystalline) properties, composition (mol% of ethylene, propylene, 1-hexene, and diene), molecular weight, and polydispersity were also studied in this work. Systematic comparisons of the proportion of catalytically [Zr]/[C*] active sites and polymerization rate constant (kp) for ansa-zirconocenes catalyzed E/diene, E/diene/1-hexene, and E/diene/propylene polymerization have not been reported before. We evaluated the addition of 1-hexene and propylene as termonomers in the copolymerization with E/diene. To make a comparison for each diene under identical conditions, we started the polymerization by introducing an 80/20 mole ratio of E/P and 0.12 mol/L of 1-hexene in the system. The catalyst behavior against different dienes, 1-hexene, and propylene is very interesting, including changes in thermal properties, cyclization of 1-hexene, and decreased incorporation of isoprene and butadiene, changes in the diffusion barriers in the system, and its effect on kp. [ABSTRACT FROM AUTHOR]

Ethylene-1-hexene copolymerization was catalyzed by TiCl4/diester/MgCl2 type Z-N catalyst activated by triethylaluminium (TEA), triisobutylaluminium (TIBA) or TEA/TIBA mixtures. Copolymerization activity decreased with increase of TIBA content in the cocatalyst. Each copolymer sample was fractionated into boiling n-heptane soluble and insoluble fractions. 1-Hexene content of the soluble fraction was 2 ∼ 6 times larger than that of the insoluble fraction. With introduction of TIBA in the cocatalyst, chemical composition distribution of the copolymer was broadened, attributable to increase of 1-hexene in the soluble fraction. Total number of active centers markedly decreased with increasing TIBA in cocatalyst, and active center number in the soluble fraction decreased more than that in the insoluble fraction. Rate constant of ethylene insertion (kpE) in the soluble fraction was much smaller than that of the insoluble fraction. Rate constant of 1-hexene insertion (kpH) of the soluble fraction became far larger than that of the insoluble fraction when TEA/TIBA ratio was lower than 80/20. In the presence of TIBA, only a part of active center precursors with stronger ability of incorporating 1-hexene were effectively activated in the soluble fraction. For the active centers in insoluble fraction, cocatalyst structure exerted more complicated effects on their activation. Active center models were proposed to explain the observed cocatalyst effects. [ABSTRACT FROM AUTHOR]

The copolymerization of ethylene (E) with isoprene (Ip) was performed catalyzed by a symmetrical catalyst exhibiting a silicon bridge [rac-Me 2 Si(2-Me-4-Ph-Ind) 2 ZrCl 2 with the combination of borate/TIBA activator. The effect of cocatalyst, Ip concentration, and polymerization temperature on the activity, molecular weight (Mw), distribution (MWD), comonomer composition, chain structure (regio- and stereoselectivity), and resulting side reactions were logically addressed. Gel-permeation chromatography (GPC) was used to characterize the Mw and polydispersity, while nuclear magnetic resonance (NMR) was employed for the chain structure of the polymers. The catalytic activity was significantly lower by increasing the Ip concentration in the feed, and the isoprene content in resulting polymers was lower under the reaction condition, leading to higher activity. Insertion of isoprene units in polymer structure demonstrates the higher regioselectivity for the 3,4 connections than the 1,4 connections and is expected to be a high-resistance polymer against acids. The MWD presented monomodal even with a higher concentration (1.44 mol/L) and did not appear as low Mw peaks of Ip. The Mw was higher with a broader MWD when purely TIBA was used as a cocatalyst, and it significantly reduced and presented a narrowed MWD with TEA in the cocatalyst. The higher efficiency of the catalyst for the higher insertion of Ip (C=C double bond) effectively modifies the polymer backbone. It is expected to be a promising candidate for easily degradable and favorable solutions for solving environmental problems caused by PE. wastes. [Display omitted] • Environmentally benign methodology reaction conditions (low temperature and pressure) are hallmarks of this approach. • Ethylene α-olefin (linear conjugated diene) copolymerization catalyzed with a symmetrical Single-site homogeneous catalyst. • Ethylene α-olefin (linear conjugated diene) copolymerization catalyzed with a symmetrical Single-site homogeneous catalyst. • The MWD demonstrated monomodal even with a higher concentration of isoprene (1.44 mol/L). • Increased insertion of isoprene may lead to easily degradable and beneficial solutions for PE waste environmental issues. [ABSTRACT FROM AUTHOR]

Copolymerization of ethylene (E) and propylene (P) and their terpolymerizations with three kinds of diene (5-ethylidene-2-norbornene (ENB), 4-vinylcyclohexene (VCH) and 1,4-hexadiene (HD)) under 4 bar monomer pressure in n-heptane solution were studied. Two ansa-zirconocenes (rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (Mt-I) and rac-Et(Ind)2ZrCl2 (Mt-II)) activated by (Ph3C)B(C6F5)4/triisobutylaluminum were used as the catalyst, respectively. In general, addition of diene depressed the polymerization activity. ENB exerted the strongest deactivation effect on Mt-I, and HD caused the strongest deactivation on Mt-II. Among the two metallocenes, activity of Mt-I was more sensitive to the diene. Increasing diene concentration in the monomer feed caused lower propylene incorporation rate and shorter average length of polypropylene sequences, and the average length of polyethylene sequences was increased by adding more HD in E/P/HD terpolymerization with Mt-II. The Mt-II/borate catalyst showed high activity and diene incorporation rate for E/P/ENB terpolymerization. In contrast, Mt-I/borate catalyst showed high activity and propylene incorporation rate for E/P copolymerization, but was nearly inactive for E/P/ENB terpolymerization. [ABSTRACT FROM AUTHOR]