Naga and Imanishi [30] studied the effects of the ligand structure of zirconocene
catalysts on the copolymerization of cyclopentene (Cp) and ethene. They found that
non-bridged zirconium complexes together with MAO as cocatalyst were not able to
incorporate cycloolefin units into the polymer chain. The copolymers obtained with
rac-[Et(Ind) 2 ]ZrCl 2 (I-1 in Fig. 3) contained not only cis-1,2-units but also 20–30%
cis-1,3-units of cyclopentene. DSC measurements showed multiple melting
X
Zr
Cl
Cl
R 2
R 3
R 4
R 5
R 6
R 7
R 6
R 5
R 4
R 7
R 3
R 2
X
Zr
Cl
Cl
R 3
R 2
R 7
X
Zr
Cl
Cl
R 2
R 2
R 5
R 5
I
I I
I I I
X=CH 2 -CH 2 , all R=H
(I-1) X=(CH 3 ) 2 C, all R=H
(II-1)
X=CH 2 -CH 2 ,
R = M e (III-1)
R 3 =CH 3
R 2 =R 7 =H
(II-2)
X=CH 2,
R=Me (III-2)
X=(CH 3 ) 2 Si,
all R=H
(I-2)
R 3 =iPr,
R 2 =R 7 = H
(II-3)
X=(CH 3 ) 2 CH
R=H
(III-3)
R 4 -R 5 =benz (I-3)
R 3 =tBu,
R 2 =R 7 =H
(II-4)
R 2 =CH 3
(I-4) X=(CH 3 ) 2 Si, all R=H
(II-5)
R 2 =CH 3 ,
R 4 -R 5 =benz
(I-5) X=(Ph) 2 C,
all R=H
(II-6)
R 3 =H,
R 2 =R 7 =tBu
(II-7)
X=(Me) 3 Pen all R=H
(II-8)
X=(Me) 3 Pen R 3 =Ph,
R 2 =R 7 =H
(II-9)
X
N
TiCl 2
R 2
R 5
R 4
R 3
Sc
THF
X
SiMe 3
SiMe 3
IV
V
X = Me 2 Si,
R 2 =R 3 =R 4 =R 5 =CH 3
(IV-1)
X=Me 3 Si,
X=PhMe 2 Si,
X=C 6 F 6 Me 2 Si,
(V-1)
(V-2)
(V-3)
R 3 =R 5 =CH 3
(IV-2)
R 4 =tBu
(IV-3)
R 4 -R 5 =benz
(IV-4)
R 1 -R 5 =benz,
R 2 -R 3 =benz,
(IV-5)
Fig. 3 Most frequently used metal catalyst precursors that can homo- or copolymerize cyclic
olefins
Polyolefins with Cyclic Comonomers
121