temperature and propene pressure (concentration). Stereo-block PPs composed of
syn- and ata-sequences were synthesized by changing these conditions during the
living polymerization of propene [29–31]. The synthesis of syn-PP-block-ata-PPblock-syn-PP by changing propene pressure is displayed in Fig. 8 [32].
4 Living Polymerization of Norbornene with
ansa-Dimethysilylene(fluorenyl)(amido)dimethyltitanium Activated with dMMAO
4.1 Homopolymerization of Norbornene
Complex 2, which is effective for propene polymerization was found to conduct
coordination-insertion-type polymerization of norbornene. In Table 3 are shown the
effects of cocatalyst in norbornene polymerization with 2 in toluene at 20
C [33, 34].
dMAO and MMAO showed good activities (approximately 1,000 kgpolymer·mol-Ti
À1 ·h
À1 ), but MAO showed very poor activity due to Me 3 Al in
MAO. Ph 3 CB(C 6 F 5 ) 4 combined with R 3 Al showed the highest activity. All the
produced polymers possessed narrow molecular weight distributions. It should be
noted that MMAO gave the narrowest M w /M n of 1.07 even in the presence of
i Bu 3 Al,
probably due to the good solubility of MMAO, suggesting that dMMAO should not
be necessary for living polymerization of norbornene with 2. The chain transfer to
R 3 Al should be suppressed at the hindered propagation chain end of norbornene.
The effect of Al/Ti ratio on the yield and the M n value are shown in Fig. 9. Both
values increased proportionally with the Al/Ti ratio, keeping the narrow molecular
weight distribution, which indicates that the propagation rate was enhanced by
excess MMAO, as observed in propene polymerization with 4-dMMAO.
Fig. 8 Synthesis of stereo-block PP with 4-dMMAO by pressure variation [32]
Trialkylaluminum-Free Modified Methylaluminoxane as a Cocatalyst for Living. . .
153
syn- and ata-sequences were synthesized by changing these conditions during the
living polymerization of propene [29–31]. The synthesis of syn-PP-block-ata-PPblock-syn-PP by changing propene pressure is displayed in Fig. 8 [32].
4 Living Polymerization of Norbornene with
ansa-Dimethysilylene(fluorenyl)(amido)dimethyltitanium Activated with dMMAO
4.1 Homopolymerization of Norbornene
Complex 2, which is effective for propene polymerization was found to conduct
coordination-insertion-type polymerization of norbornene. In Table 3 are shown the
effects of cocatalyst in norbornene polymerization with 2 in toluene at 20
C [33, 34].
dMAO and MMAO showed good activities (approximately 1,000 kgpolymer·mol-Ti
À1 ·h
À1 ), but MAO showed very poor activity due to Me 3 Al in
MAO. Ph 3 CB(C 6 F 5 ) 4 combined with R 3 Al showed the highest activity. All the
produced polymers possessed narrow molecular weight distributions. It should be
noted that MMAO gave the narrowest M w /M n of 1.07 even in the presence of
i Bu 3 Al,
probably due to the good solubility of MMAO, suggesting that dMMAO should not
be necessary for living polymerization of norbornene with 2. The chain transfer to
R 3 Al should be suppressed at the hindered propagation chain end of norbornene.
The effect of Al/Ti ratio on the yield and the M n value are shown in Fig. 9. Both
values increased proportionally with the Al/Ti ratio, keeping the narrow molecular
weight distribution, which indicates that the propagation rate was enhanced by
excess MMAO, as observed in propene polymerization with 4-dMMAO.
Fig. 8 Synthesis of stereo-block PP with 4-dMMAO by pressure variation [32]
Trialkylaluminum-Free Modified Methylaluminoxane as a Cocatalyst for Living. . .
153