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  • 1
    Electronic Resource
    Electronic Resource
    Metallocene catalysts for olefin polymerizations. XXIV. Stereoblock propylene polymerization catalyzed by rac-[anti-ethylidene(1-η5-tetramethylcyclopentadienyl)(1-η5-indenyl)dimethyltitanium: A two-state propagationSee Reference 1. (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2601-2617 
    Details
    ISSN: 0887-624X
    Keywords: Ziegler-Natta catalysts ; ansa-metallocene catalyst ; thermoplastic elastomeric poly(propylene) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic-anti-[ethylidene(1-η5-tetramethylcyclopentadienyl) (1-η5-indenyl)dimethyltitanium (6) has been synthesized and its molecular structure determined by x-ray diffraction methods. The two Ti=Me(1) and Ti=Me(2) units have bond distances differing by 0.08 Å and their proton NMR resonances are separated by over 1 ppm. Using this compound and methylaluminoxane (MAO) as the activator, at 25°C the 6/MAO catalyst produced polypropylene having crystalline domain with physical crosslinks. The polymers obtained at lower polymerization temperatures are rheologically liquids. The behaviors of this catalyst system resembles closely the previously reported rac-[anti-ethylidene(1-η5-tetramethylcyclopentadienyl) (1-η5-indenyl)dichlorotitanium (4)/MAO system. The structure of 6 determined here furnishes tangible support for the proposed two-state (isomeric)-switching propagation mechanism. Addition of MAO to 6 causes broadening of the Me(1) resonance in the 1H-NMR spectra, and 6 is decomposed by Ph3C+B(C6F5)-4. © 1992 John Wiley & Sons, Inc.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301215
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  • 2
    Electronic Resource
    Electronic Resource
    Syndioselective propylene polymerization catalyzed by rac-2,2-dimethylpropylidene (1-η5-cyclopentadienyl) (1-η5-fluorenyl) dichlorozirconium (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 661-673 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syndioselective propylene polymerization has been promoted by rac-2,2-dimethylpropylidene (1-η5-cyclopentadienyl) (1-η5-fluorenyl) dichlorozirconium (1). The active catalytic species were generated using either triphenylcarbenium tetrakis (pentafluorophenyl) borate (2) (Zr+ method) or methylaluminoxane (MAO method). The former exhibited much higher activity than the latter, especially at low polymerization temperatures (Tp). Syndiotactic poly (propylene) (s-PP) obtained at Tp = -20°C has Tm approaching 160°C, [rrrr] pentad fraction of 0.92 to 0.95, and 45% crystallinity (Xc). It crystallized in two antichiral unit cells B and C. The C structure is favored by low temperature of polymerization, slow crystallization from melt, and annealing. The s-PP has M̄w/M̄n ranging from 3.6 to 4.4, which can be separated into stereoregular fractions soluble in heptane and hexane and stereoirregular fractions soluble in pentane, ether, and acetone. Therefore, this system cannot be considered to be a single-site catalyst. A parallel study was made on the isopropylidene (1-η5-cyclopentadienyl) (1-η5-fluorenyl) dichlorozirconium (3)/MAO catalyst. Molecular mechanics calculations were performed for all combinations of the configuration of asymmetric centers. The steric energy favors syndiotactic enchainment for both catalysts 1 and 3, with 1 forming the more syndioselective catalyst. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320405
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  • 3
    Electronic Resource
    Electronic Resource
    Olefin terpolymerizations. II. 4-vinylcyclohexene and cyclooctadiene (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2787-2793 
    Details
    ISSN: 0887-624X
    Keywords: Ziegler-Natta catalysis ; EPDM synthesis ; metallocene catalyst ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Vinylcyclohexene (VCH) and cyclooctadiene (COD) were investigated as termonomers in EPDM (ethylene/propylene/diene) synthesis by using rac-ethylenebis (1-η5-indenyl) zir-conium dichloride (1) as a catalyst precursor. Homopolymerizations of VCH, vinylcycloh-exane and cyclohexene were compared. The parameter Kπκp, which is the apparent rate constant for Ziegler-Natta polymerization, is about the same for VCH and vinylcyclohexanebut is 10 times smaller for cyclohexene. Therefore, the linear olefinic double bond is more active than the cyclic internal double bond. VCH reduces ethylene polymerization rate but not propylene polymerization rate in copolymerizations. In terpolymerizations, VCH tends to suppress ethylene incorporation especially at elevated polymerization temperature and Lowers the polymer MW by about two-fold. COD has very low activity as a termonomer. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331612
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  • 4
    Electronic Resource
    Electronic Resource
    Olefin terpolymerizations. I. 1,4-hexadiene (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 979-987 
    Details
    ISSN: 0887-624X
    Keywords: Ziegler-Natta polymerization ; EPDM ; metallocene catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylene (E), propylene (P), and 1,4-hexadiene (HD) were terpolymerized with rac-1,2-ethylenebis (1-η5-indenyl) zirconium(IV) dichloride and methylaluminoxane (Et[Ind]2ZrCl2/MAO), and compared with the copolymerizations of E/P, E/HD, P/HD, and terpolymerization using ethylidene norbornene (ENB) as the termonomer. HD lowers the polymerization activity, the effect is more pronounced for P/HD and E/P/HD using large amount of P, than for E/HD and E/P/HD using feed low in P. The polymer molecular weight is most strongly affected by the temperature of polymerization (Tp), whereas the E/P ratio in the feed has virtually no effect. The reactivity ratios rE and rP are 3.0 and 0.3, respectively, at 20°C but rP becomes larger than rE at TP = 70°C. 1H-NMR spectra showed occurrence of cycloaddition in the homopolymerization of HD; on the other hand, HD is incorporated in the terpolymer only by linear 1,2-addition. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330612
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  • 5
    Electronic Resource
    Electronic Resource
    Olefin terpolymerizations. III. Symmetry, sterics, and monomer structure in ansa-zirconocenium catalysis of EPDM synthesis (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2795-2801 
    Details
    ISSN: 0887-624X
    Keywords: Ziegler-Natta catalysis ; EPDM synthesis ; metallocene catalyst ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylenebis (η5-fluorenyl) zirconium dichloride (1) and rac-dimethylsilylene bis (1-η5-in-denyl) zirconium dichloride (2) were activated with methylaluminoxane (MAO) to catalyze ethylene (E) propylene (P) copolymerizations. The former produces high MW copolymer at 20°C rich in ethylene with reactivity ratio values of rE = 1.7 and rP 〈0.01, whereas the latter produces lower MW random copolymers with rE = 1.32 and rp = 0.36. Ethylidene norbornene (ENB) complexes with 1/MAO but does not undergo insertion in the presence of E and P. In contrast, 2/MAO catalyzes terpolymerization incorporating 9-15 mol % of ENB with slightly lower MW and activity than the corresponding copolymerizations. In comparison, 1,4-hexadiene was incorporated by 2/MAO with much lower A and MW. Terpolymerizations were also conducted with vinylcyclohexene using both catalyst systems. The steric and electronic effects in these processes were discussed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331613
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  • 6
    Electronic Resource
    Electronic Resource
    Segmented poly(ether urethane) films containing ferrocene units in the hard segments (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1599-1607 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Segmented poly(ether urethanes) were synthesized from polypropylene glycol (PPG) and 4,4′-methylene-bis(phenyl-isocyanate) (MDI), using 1,1′-bis(β-aminoethyl)ferrocene (BAF) and 1,1′-bis(β-hydroxyethyl)ferrocene (BHF) as chain extenders. These polymers were characterized by infrared and 13C-NMR spectroscopy. Mass spectrometry was also utilized to determine the linkage of BAF and BHF in these polymers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240717
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  • 7
    Electronic Resource
    Electronic Resource
    Asymmetric zirconocene precursors for catalysis of propylene polymerization (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2817-2824 
    Details
    ISSN: 0887-624X
    Keywords: metallocenes ; olefin polymerization ; Ziegler-Natta catalysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic isopropylidene (1-η5-cyclopentadienyl)(1-η5-indenyl) dichlorozirconium and the 3-methylindenyl derivative have been synthesized and characterized. These precursors activated with methylaluminoxane produce poly(propylene) with hemiisotactic microstructures. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321503
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  • 8
    Electronic Resource
    Electronic Resource
    Heptane-soluble homogeneous zirconocene catalyst: Synthesis of a single diastereomer, polymerization catalysis, and effect of silica supports (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2093-2108 
    Details
    ISSN: 0887-624X
    Keywords: zirconocene ; ethylene polymerization ; propylene polymerization ; silica-supported catalyst ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(1-indenyl)-di[1′S, 2′R, 5′S)-methoxy]silane (1) was converted into a mixture of corresponding ansa-diastereomeric zirconocenes. Further purification afforded a single dia-stereomer, di[(1′S, 2′R, 5′S)-methoxy] silylene-bis[η5-1(R, R)-(+)-indenyl] dichlorozirconium (2), which is optically active and hydrocarbon soluble. Extremely rapid ethylene, propylene, and ethylene-hexene polymerizations were observed both in toluene and n-heptane solutions; for instance, at 50°C, activity for ethylene polymerization reaches ∼ 1.5×1010 (g of PE/((mol of Zr) · [C2H4] · h). The “bare” zirconocenium ion generated from 2/TIBA/Ph3CB(C6F5)4 exhibits unusual polymerization behaviors; the polymerization activity increases monotonically with temperature of polymerization (Tp) up to a conventional polymerization condition (50-70°C), and the 13C NMR study shows that the isotactic poly-propylene obtained has fairly high [mmmm] methyl pentad distributions at high Tp (≤25°C with [mmmm] ∼ 0.93-0.75) and a perfect stereoregularity at low Tp (≤0°C with [mmmm] 〉 0.99). The catalyst precursors 2 and Et(Ind)2ZrCl2 (3) supported on silica by different approaches produced poly(olefins) of different molecular weights and stereoregularities, and a methylaluminokane and Ph3CB(C6F5)4 free silica-supported zirconocene system was found to be activated by triisobutylaluminum. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331301
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  • 9
    Electronic Resource
    Electronic Resource
    Polymerizations of olefins and diolefins catalyzed by monocyclopentadienyltitanium complexes containing a (dimethylamino)ethyl substituent and comparison with ansa-zirconocene systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 319-328 
    Details
    ISSN: 0887-624X
    Keywords: metallocenes ; Ziegler-Natta catalysis ; olefin polymerizations ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: {[2-(dimethylamino)ethyl]cyclopentadienyl}titanium trichloride (CpNTiCl3, 1) was activated with methylaluminoxane (MAO) to catalyze polymerizations of ethylene (E), propylene (P), ethylidene norbornene (ENB), vinylcyclohexene (VCH), and 1,4-hexadiene (HD). The dependence of homopolymerization activity (A) of 1/MAO on olefin concentration ([M]n) is n = 2.0 ± 0.5 for E and n = 1.8 ± 0.2 for P. The value of n is 2.4 ± 0.2 for CpTiCl3/MAO catalysis of ethylene polymerization; this system does not polymerize propylene. 1/MAO catalyzes HD polymerization at one-tenth of AH for 1-hexene, probably because of chelation effects in the HD case. The copolymerization of E and P has reactivity ratios of rE = 6.4 and rP = 0.29 at 20°C, and rErP = 1.9, which suggests 1/MAO may be a multisite catalyst. The copolymerization activity of CpTiCl3/MAO is 50 times smaller than that of CpNTiCl3/MAO. Terpolymerization of E/P/ENB has A of 105 g of polymer/(mol of Ti h), incorporates up to 14 mol % (∼ 40 wt %) of ENB, and high MW's of 1 to 3 × 105. All of these parameters are surprisingly insensitive to the ENB concentration. The E/P/VCH terpolymerization has comparable A value of (1.3 ± 0.3) × 105 g/(mol of Ti h). The incorporation of VCH in terpolymer increases with increasing [VCH]. Terpolymerization with HD occurs at about one-third of the A of either ENB or VCH; the product HD-EPDM is low in molecular weight and contains less than 4% of HD. These terpolymerization results are compared with those obtained previously for three zirconocene precursors: rac-ethylenebis(1-η5-indenyl)dichlorozirconium (6), rac-(dimethylsilylene)bis(1-η5-indenyl)dichlorozirconium (7), and ethylenebis(9-η5-fluorenyl)dichlorozirconium (8). The last compound is a particularly poor terpolymerization catalyst; it incorporates very little VCH or HD and no ENB at all. 7/MAO is a better catalyst for E/P/VCH terpolymerization, while 6/MAO is superior in E/P/HD terpolymerization. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 319-328, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Step-growth cationic polymerization of α-hydroxyisopropylferrocene (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 347-357 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Hydroxyisopropylferrocene, HPF, was synthesized in good yield and polymerized at 20°C with either SnCl4 or BF3OEt2. The polymerization proceeds by self-alkylation of the stable intermediate ferrocenylcarbenium ion on the cyclopentadienyl ring to form oligomers that contain both homoannular and heteroannular links. The unusually high stability of the α-isopropylferrocenylcarbenium ion was demonstrated by synthesizing and isolating α-isopropylferrocenylcarbenium tetrafluoborate from HPF and using it to initiate the polymerization of styrene. Initiation was successful at 20° and at 0°C, but no polymerization occurred -78°C. The condensation of ferrocene and acetone in the presence of AlCl3 gave oligomers having structures very similar to those obtained from the cationic polymerization of isopropenylferrocene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240212
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