Polymerizations of olefins and diolefins catalyzed by monocyclopentadienyltitanium complexes containing a (dimethylamino)ethyl substituent and comparison with ansa-zirconocene systems
✍ Scribed by James C. W. Chien; Zhengtian Yu; Maria M. Marques; Juan C. Flores; Marvin D. Rausch
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 191 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0887-624X
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✦ Synopsis
{[2-(dimethylamino)
ethyl]cyclopentadienyl}titanium trichloride (Cp N TiCl 3 , 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 Å 2.0 { 0.5 for E and n Å 1.8 { 0.2 for P. The value of n is 2.4 { 0.2 for CpTiCl 3 /MAO catalysis of ethylene polymerization; this system does not polymerize propylene. 1/MAO catalyzes HD polymerization at one-tenth of A H for 1-hexene, probably because of chelation effects in the HD case. The copolymerization of E and P has reactivity ratios of r E Å 6.4 and r P Å 0.29 at 20ЊC, and r E r P Å 1.9, which suggests 1/MAO may be a multisite catalyst. The copolymerization activity of CpTiCl 3 /MAO is 50 times smaller than that of Cp N TiCl 3 /MAO. Terpolymerization of E/P/ENB has A of 10 5 g of polymer/(mol of Ti h), incorporates up to 14 mol % ( Ç 40 wt %) of ENB, and high MW's of 1 to 3 1 10 5 . 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) 1 10 5 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-h 5 -indenyl)dichlorozirconium ( 6), rac-(dimethylsilylene)bis(1-h 5 -indenyl)dichlorozirconium (7), and ethylenebis(9-h 5 -fluorenyl)dichlorozirconium ( 8). The last compound is a particularly poor terpolymerization catalyst; it incorporates very little VCH or HD and no ENB at all.