The dinuclear half-sandwich CGCs (constrained geometry catalyst) with a polymethylene bridge, $[Ti({\eta}^5 : {\eta}^1-indenyl)SiMe_2NCMe_3]_2(CH_2)_n]$[n = 6 (1) and 12 (2)], have been employed in the copolymerization of ethylene and norbornene (NBE). To compare the mononuclear metalloce...
The dinuclear half-sandwich CGCs (constrained geometry catalyst) with a polymethylene bridge, $[Ti({\eta}^5 : {\eta}^1-indenyl)SiMe_2NCMe_3]_2(CH_2)_n]$[n = 6 (1) and 12 (2)], have been employed in the copolymerization of ethylene and norbornene (NBE). To compare the mononuclear metallocene catalysts; $Ti({\eta}^5 : {\eta}^1-2-hexylindenyl)SiMe_2NCMe_3$ (3), $(Cp^* SiMe_2NCMe_3)$Ti (Dow CGC) (4) and ansa-$Et(Ind)_2ZrCI_2$ (5), were also studied for the copolymerization of ethylene and NBE. It was found that the activity increased in the order: 1 < 2 < 3 < 5 < 4, indicating that the presence of the bridge between two the CGC units contributed to depressing the polymerization activity of the CGCs. This result strongly suggests that the implication of steric disturbance due to the presence of the bridge may playa significant role in slowing the activity. Dinuclear CGCs have been found to be very efficient for the incorporation of NBE onto the polyethylene backbone. The NBE contents in the copolymers formed ranged from 10 to 42%, depending on the polymerization conditions. Strong chemical shifts were observed at ${\delta}$42.0 and 47.8 of the isotactic alternating NBE sequences, NENEN, in the copolymers with high NBE contents. In addition, a resonance at 47.1 ppm for the sequences of the isolated NBE, EENEE, was observed in the $^{13}C-NMR$ spectra of the copolymers with low NBE contents. The absence of signals for isotactic dyad at 48.1 and 49.1 ppm illustrated there were no isotactic or microblock (NBE-NBE) sequences in the copolymers. This result indicated that the dinuclear CGCs were effective for making randomly distributed ethylene-NBE copolymers.
The dinuclear half-sandwich CGCs (constrained geometry catalyst) with a polymethylene bridge, $[Ti({\eta}^5 : {\eta}^1-indenyl)SiMe_2NCMe_3]_2(CH_2)_n]$[n = 6 (1) and 12 (2)], have been employed in the copolymerization of ethylene and norbornene (NBE). To compare the mononuclear metallocene catalysts; $Ti({\eta}^5 : {\eta}^1-2-hexylindenyl)SiMe_2NCMe_3$ (3), $(Cp^* SiMe_2NCMe_3)$Ti (Dow CGC) (4) and ansa-$Et(Ind)_2ZrCI_2$ (5), were also studied for the copolymerization of ethylene and NBE. It was found that the activity increased in the order: 1 < 2 < 3 < 5 < 4, indicating that the presence of the bridge between two the CGC units contributed to depressing the polymerization activity of the CGCs. This result strongly suggests that the implication of steric disturbance due to the presence of the bridge may playa significant role in slowing the activity. Dinuclear CGCs have been found to be very efficient for the incorporation of NBE onto the polyethylene backbone. The NBE contents in the copolymers formed ranged from 10 to 42%, depending on the polymerization conditions. Strong chemical shifts were observed at ${\delta}$42.0 and 47.8 of the isotactic alternating NBE sequences, NENEN, in the copolymers with high NBE contents. In addition, a resonance at 47.1 ppm for the sequences of the isolated NBE, EENEE, was observed in the $^{13}C-NMR$ spectra of the copolymers with low NBE contents. The absence of signals for isotactic dyad at 48.1 and 49.1 ppm illustrated there were no isotactic or microblock (NBE-NBE) sequences in the copolymers. This result indicated that the dinuclear CGCs were effective for making randomly distributed ethylene-NBE copolymers.
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가설 설정
as the formation of good copolymer. 7"'s increasing pattern according to the increase ofNBE contents in copolymer is just normal. The most important feature about Tg measurement is that the nature of the catalyst appears to have considerable effect on Tg (Figure 2).
제안 방법
In order to investigate the catalytic behavior of the dinu- clear CGC 1 and 2, these were delivered for the polymerization of ethylene and NBE in the presence of MMAO ([Al]/ [Ti] ratio of 2,000). A series of polymerization runs have been carried out at eight compositions of monomer feed, and results are shown in Tables I and IL At the same time the mononuclear metallocene complexes rac-Et(Ind)2ZrCl2 (EBI, 5), M%S"MCpNBuJTiCL (Dow CGC, 4), and Me2Si[(n- HexyeIndT'TBuJTiCe (Hex-CGC, 3) have been studied for the comparison (Scheme I).
4%. This observation has been proceeded to figure out how the catalyst structure have an effect on the microstructure of ethylene-NBE copolymer. It is evident that 13C-NMR spectra from the copolymers generated by the catalysts 1, 2 and 3 display almost identical appearance as shown in Figure 4.
In this study we describe the catalytic behavior of the dinuclear CGC 1 and 2 along with the mononuclear metallocene catalysts 3, 4, and 5 to figure out principally the properties of ethylene-NBE copolymerization. It was found that the catalytic activity with five catalysts increased in the order of 4>5>3>2>1, which illustrated that the dinuclear catalysts 1 and 2 represented lower activity than the mononuclear catalysts.
성능/효과
of ethylene-NBE copolymerization. It was found that the catalytic activity with five catalysts increased in the order of 4>5>3>2>1, which illustrated that the dinuclear catalysts 1 and 2 represented lower activity than the mononuclear catalysts. Activities of the catalyst 2 with twelve methylenes as a bridge exhibit greater than those of the catalyst 1 with six methylenes.
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