ISSN:
0887-624X
Schlagwort(e):
metallocenes
;
Ziegler-Natta catalysis
;
olefin polymerizations
;
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
{[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
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
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