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The dynamics study of metallocene catalyst using molecular dynamics
Applied Surface Science 130–132 Ž1998. 501–505
The dynamics study of metallocene catalyst using molecular dynamics Takeshi Sato, Yasunori Oumi, Hiromitsu Takaba, Momoji Kubo, Abhijit Chatterjee, Kazuo Teraishi, Akira Miyamoto ) Department of Materials Chemistry, Graduate School of Engineering, Tohoku UniÕersity, Aoba, Aramaki, Aoba-ku, Sendai 980-77, Japan Received 1 September 1997; accepted 24 October 1997
Abstract Molecular dynamics ŽMD. simulation was applied to investigate the dynamics of metallocene catalyst. We introduced a cocatalyst, large substituents on cyclopentadienyl ŽCp. ring, and a longer polymer chain, along with a cationic active center. The study on interaction between the active center and the cocatalyst revealed that one or two fluorines of ŽC 6 F5 .4 By are coordinated to the unsubstituted coordination space in the most stable state. A metastable state was also found, where ŽC 6 F5 .4 By interacts with the whole active center, and moreover one or two fluorines come closer to a Si atom. The mobility of the polymer chain bonded to a higher isospecific metallocene active center was found to be more retarded than that bonded to a lower stereospecific metallocene active center. The investigation of the dynamics of polymer chain using our MD simulations would allow us to predict the stereospecificity of various metallocene catalysts. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Metallocene catalyst; Molecular dynamics; Cocatalyst; Polymer chain; Stereoregularity
1. Introduction The metallocene catalysts developed by Kaminsky et al. w1,2x have abilities to synthesize the polymers with desired tacticity or uniform copolymer with very narrow compositional and molecular weight distributions. Therefore, many research projects have been carried out for further refinement of these system and for the detailed explanation of their polymerization mechanism. Experimentally, Spaleck et al. w3x synthesized new optimized metallocenes with various aromatic sub-
)
Corresponding author. Fax: q81-22-217-7235; e-mail: [email protected].
stituents and reported that the catalytic activity is well explained by the electronic effects, whereas the steric effects play an important role in the stereospecifity and the increase of the molecular weights of the polymers. Many theoretical calculations have also been carried out to clarify the insertion reaction of olefin w4–6x, the change of electronic state during the reaction w7x, the active energy of olefin insertion w8,9x, the existence of a-agostic interaction w8,9x, a correlation between the substituents on cyclopentadienyl ŽCp. ring and the stereoregularity of synthesized polymer w8,10x, etc. These calculations provided the detail information near the active center, but there are few calculations considering the effect of cocatalysts, supports, longer polymer chains and temperature which are the key factors in the reactions.
0169-4332r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 1 6 9 - 4 3 3 2 Ž 9 8 . 0 0 0 6 2 - 2
502
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
In order to calculate such a larger system containing the above factors and to investigate the dynamics of metallocene catalysts,molecular dynamics ŽMD. method was employed. More precisely, we investigated the interaction between the cationic active center and the counter anion as a cocatalyst, and the correlation between the substituents on Cp ring and the mobility of polymer chain.
2. Method We used the Cerius2 code to perform MD simulations. Universal Force Field ŽUFF. potential w11,12x was used to describe the interaction within the metallocene catalyst system. Seven kinds of metallocene active centers were studied. The catalyst models are illustrated in Fig. 1. PP re p re s e n ts p o ly p ro p y le n e a n d ŽŽCH 2 CHŽCH 3 ..14 CH 2 CH 3 . was used in our calculations. As a cocatalyst, ŽC 6 F5 .4 By was used. Before MD simulation, QEq charge calculations w13x were carried out to assign the atomic charge and then sufficient minimizing calculations were carried out. MD simulations were performed at constant NVT ŽT s 343 K.. The calculation investigating the inter-
action between the cationic active center and the counter anion, and that investigating the correlation between the substituents on Cp ring and the mobility of polymer chain were carried out for 50 000 and 100 000 steps, respectively, where a time step corresponds to 0.5 = 10y1 5 seconds. During the simulation all the systems are relaxed and no constraints were imposed. In order to check the UFF potential, we compared the calculated structure of SiMe 2 Cp 2 ZrCHq 3 with available experimental data w14x. The deviation of the calculated bond lengths and bond angles from the experimental values were very small, and were be˚ and 0.06 A˚ and between 4.28 and 6.68, tween 0.00 A respectively. Therefore, we confirmed the validity of UFF potential parameters used here.
3. Results and discussion First, we investigated the interaction between the . and the counter active center ŽSiMe 2 Cp 2 ZrCHq 3 y y. ŽŽ . anion C 6 F5 4 B or Cl used as cocatalysts. Since the calculation using only one initial structure seems to be unreliable, the calculation using several initial structures were carried out. Fig. 2a shows the most
Fig. 1. The models of seven metallocene cationic active centers used in our MD simulation.
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
503
. Ž . ŽŽC 6 F5 .4 By. as cocatalyst. Ža. Fig. 2. The interaction between the Ža. cationic active center ŽSiMe 2 Cp 2 ZrCHq 3 and the counter anion b shows the most stable state and Žb. shows the metastable state.
stable adsorption state, where one or two fluorines of ŽC 6 F5 .4 By are coordinated to the unsaturated coordination space. This result is consistent with the experimental results w15,16x. It was also observed that a metastable state is in existence, where ŽC 6 F5 .4 By interacts with whole active center, and moreover one or two F come closer to Si atom ŽFig. 2b.. Table 1 shows the stabilization energy due to the coordination of ŽC 6 F5 .4 By obtained from our MD calculations. The energy difference between the most stable state and the metastable state is not so large and the value is about 10 kcalrmol. Therefore, when the neighbourhood of Zr atom is more crowded with substituents on Cp ring and polymer chain, it becomes difficult for ŽC 6 F5 .4 By to access the Zr atom and the metastable state which was obtained from our calculation may become dominant. When
we used Cly as a counter anion for the comparison with ŽC 6 F5 .4 By, although Cly is not a real cocatalyst, Cly is adsorbed only to the unsaturated coordination space. The stabilization energy by the coordination of ŽC 6 F5 .4 By is about two times lower than that of Cly ŽTable 1., which indicates that the
Table 1 The stabilization energy by coordination of the counter anion to the cationic active center. These energy are obtained from our MD calculation Counter anion
Stabilization energy Žkcalrmol.
ŽC 6 F5 .4 By Žmost stable. ŽC 6 F5 .4 By Žmetastable. Cly
y41 y30 y86
Fig. 3. The locus of Si–Zr–C a angle using catalyst 5 during the simulation.
504
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
Fig. 4. The distribution histogram of Si–Zr–C a angle using catalyst 5 at the equilibrium state.
electrostatic interaction between the active center and ŽC 6 F5 .4 By is weak and ŽC 6 F5 .4 By must be labile enough to be displaced by the polymerizing monomer. We investigated the correlation between the substituents on Cp ring and the mobility of polymer chain. Fig. 3 shows a locus of Si–Zr–C a angle ŽC a : first carbon of polymer chain. using catalyst 5 during the simulation. Probably because the angle at the first stage of calculation Žabout 1258. was strained, the angle shifted to the range between 1608 and 1808 quickly and reached the equilibrium state in this range. Fig. 4 shows the distribution histogram of Si–Zr–C a angle of catalyst 5 at the equilibrium state and the range of Si–Zr–C a angle appeared with more than 2% of frequency was examined. Similarly,
the amplitudes of the fluctuation of this angle were also examined for the other catalysts from the distribution histograms like Fig. 4. The results are summarized in Table 2 with the experimental data w3x Žisotactic stereospecificity of produced polypropylene.. When we used a low isospecific and non substituted metallocene catalyst like 1, the Si–Zr–C a angle fluctuated between 1328 and 1808 Žvariation is 488., which indicates that when there is a large space around the polymer chain, polymer chain can move around easily. When we used a high isospecific and more steric substituted metallocene catalyst like 6, the variation of Si–Zr–C a angle was about 188, which indicates that polymer chain in the crowd of more steric substituents can not move around easily. Generally Table 2 shows the tendency that the higher the isotactic stereospecificity of the catalysts, the more restrained the mobility of polymer chain. In order to produce more stereospecific polymer, uniform monomer coordination has to be obtained, which is believed to be achieved by controlling the end of the polymer chain by the ligand frame of the active complex w8,10x. Our simulation results represent that there is a correlation between the mobility of the end of polymer chain, i.e., the mobility of Si–Zr–C a angle, and the substituents on Cp ring. In other words, the mobility of Si–Zr–C a angle is more restrained when a high isospecific metallocene catalyst is used. Contrastly a low isospecific metallocene catalyst does not interfere with the motion of the chain. This correlation is consistent with the isotactic stereospecificity obtained from experiments. Therefore, the investigation of the dynamics of polymer chain using the current MD model should predict the stereoregularity of various metallocene catalysts. Moreover, by extending the model to include
Table 2 The range of angle ŽSi–Zr–C a . and experimental data Žisotactic stereospecificity of produced polypropylene. using various metallocene catalysts. ŽExperimental condition: 708C, Zr:Al s 1:15 000. Metallocene
Range of Si–Zr–C a angle Žvariation. Ždegree.
Experimental data: mmmm Ž%.
1 2 3 4 5 6 7
132 ; 180 Ž48. 149 ; 177 Ž28. 159 ; 180 Ž21. 158 ; 179 Ž21. 160 ; 180 Ž20. 153 ; 171 Ž18. 150 ; 177 Ž27.
y 81.7 88.6 86.5 95.2 99.1 78.1
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
the support, the prediction of stereoregularity of supported metallocene catalyst can also be expected. 4. Conclusion Using MD simulation, the dynamics of metallocene catalyst systems containing cocatalysts, large substituents on Cp ring and long polymer chains was investigated. One or two fluorine of ŽC 6 F5 .4 By are coordinated to the unsubstituted coordination space in the most stable state. It is observed that metastable state is in existence, where ŽC 6 F5 .4 By interacts with whole active center and moreover one or two fluorine comes closer to Si atom. By investigating the dynamics of polymer chain for various substituted metallocene catalysts, it was found that there is a correlation among the mobility of the end of polymer chain, substituents on Cp ring and the stereoregularity of polymer. Therefore, the investigation of the dynamics of polymer chain using the current MD model should predict the stereoregularity of various metallocene catalysts. For industry, the development of supported metallocene catalyst is expected and recently a lot of studies about the heterogeneous metallocene catalyst were carried out w17–27x. Experimentally, there is a difference in stereoregularity between the product synthesized in homogeneous system and that synthesized in heterogeneous system using the same active center w23–27x. This indicates that the support influences the stereoregularity. Therefore in order to investigate the effect of supports on the polymer stereoregularity, we plan to compare the dynamics of metallocene catalyst in both homogeneous and heterogeneous system. References w1x H. Sinn, W. Kaminsky, Adv. Organomet. Chem. 18 Ž1980. 99.
505
w2x W. Kaminsky, K. Kulper, H.H. Brintzinger, F.R.W.P. Wild, Angew. Chem., Int. Ed. Engl. 24 Ž1985. 507. w3x W. Spaleck, F. Kuber, A. Winter, J. Rohrmann, B. Bachmann, M. Antberg, V. Doll, E.F. Poulos, Organometallics 13 Ž1994. 954. w4x R.J. Meier, G.H.J. van Doremaele, S. Italori, F. Buda, J. Am. Chem. Soc. 116 Ž1994. 7274. w5x S. Italori, F. Buda, Macromol. Symp. 89 Ž1995. 369. w6x S. Italori, F. Buda, Molecular Physics 87 Ž1996. 801. w7x L.A. Castonguay, A.K. Rappe, J. Am. Chem. Soc. 114 Ž1992. 5832. w8x H. Kawamura-Kuribayashi, N. Koga, K. Morokuma, J. Am. Chem. Soc. 114 Ž1992. 8687. w9x T. Yoshida, N. Koga, K. Morokuma, Organometallics 14 Ž1995. 746. w10x T. Yoshida, N. Koga, K. Morokuma, Organometallics 15 Ž1996. 766. w11x A.K. Rappe, C.J. Casewit, K.S. Colwell, W.A. Goddard III, W.M. Skiff, J. Am. Chem. Soc. 114 Ž1992. 10024. w12x A.K. Rappe, K.S. Colwell, Inorg. Chem. 32 Ž1993. 3438. w13x A.K. Rappe, W.A. Goddard, J. Phys. Chem. 95 Ž1991. 3358. w14x R.F. Jordan, C.S. Bajgur, R. Willet, B. Scott, J. Am. Chem. Soc. 108 Ž1986. 7410. w15x X. Yang, C.L. Stern, T.J. Marks, Organometallics 10 Ž1991. 840. w16x L. Jia, X. Yang, C.L. Stern, T.J. Marks, Organometallics, In press. w17x K. Soga, M. Kaminaka, Macromol. Chem., Rapid Commun. 13 Ž1992. 221. w18x K. Soga, T. Shiono, H.J. Kim, Macromol. Chem. 194 Ž1993. 3499. w19x F. Langhauser, J. Kerth, M. Kersting, P. Kolle, D. Lilge, P. Muller, Die Angewandte Makromolekulare Chemie 223 Ž1994. 155. w20x K. Soga, M. Kaminaka, Macromol. Chem. Phys. 195 Ž1994. 1369. w21x K. Soga, T. Arai, H. Nozawa, T. Uozumi, Macromol. Symp. 97 Ž1995. 53. w22x P. Roos, G.B. Meier, J.J.C. Samson, G. Weickert, K.R. Westerterp, Macromol. Rapid Commun. 18 Ž1997. 319. w23x W. Kaminsky, F. Renner, Macromol. Chem., Rapid Commun. 14 Ž1993. 239. w24x K. Soga, M. Kaminaka, Macromol. Chem. 194 Ž1993. 1745. w25x K. Soga, H.J. Kim, T. Shiono, Macromol. Chem. Phys. 195 Ž1994. 3347. w26x K. Soga, T. Arai, H. Nozawa, T. Uozumi, Macromol. Rapid Commun. 16 Ž1995. 905. w27x Y.S. Ko, T.K. Han, J.W. Park, S.I. Woo, Macromol. Rapid Commun. 17 Ž1996. 769.
The dynamics study of metallocene catalyst using molecular dynamics Takeshi Sato, Yasunori Oumi, Hiromitsu Takaba, Momoji Kubo, Abhijit Chatterjee, Kazuo Teraishi, Akira Miyamoto ) Department of Materials Chemistry, Graduate School of Engineering, Tohoku UniÕersity, Aoba, Aramaki, Aoba-ku, Sendai 980-77, Japan Received 1 September 1997; accepted 24 October 1997
Abstract Molecular dynamics ŽMD. simulation was applied to investigate the dynamics of metallocene catalyst. We introduced a cocatalyst, large substituents on cyclopentadienyl ŽCp. ring, and a longer polymer chain, along with a cationic active center. The study on interaction between the active center and the cocatalyst revealed that one or two fluorines of ŽC 6 F5 .4 By are coordinated to the unsubstituted coordination space in the most stable state. A metastable state was also found, where ŽC 6 F5 .4 By interacts with the whole active center, and moreover one or two fluorines come closer to a Si atom. The mobility of the polymer chain bonded to a higher isospecific metallocene active center was found to be more retarded than that bonded to a lower stereospecific metallocene active center. The investigation of the dynamics of polymer chain using our MD simulations would allow us to predict the stereospecificity of various metallocene catalysts. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Metallocene catalyst; Molecular dynamics; Cocatalyst; Polymer chain; Stereoregularity
1. Introduction The metallocene catalysts developed by Kaminsky et al. w1,2x have abilities to synthesize the polymers with desired tacticity or uniform copolymer with very narrow compositional and molecular weight distributions. Therefore, many research projects have been carried out for further refinement of these system and for the detailed explanation of their polymerization mechanism. Experimentally, Spaleck et al. w3x synthesized new optimized metallocenes with various aromatic sub-
)
Corresponding author. Fax: q81-22-217-7235; e-mail: [email protected].
stituents and reported that the catalytic activity is well explained by the electronic effects, whereas the steric effects play an important role in the stereospecifity and the increase of the molecular weights of the polymers. Many theoretical calculations have also been carried out to clarify the insertion reaction of olefin w4–6x, the change of electronic state during the reaction w7x, the active energy of olefin insertion w8,9x, the existence of a-agostic interaction w8,9x, a correlation between the substituents on cyclopentadienyl ŽCp. ring and the stereoregularity of synthesized polymer w8,10x, etc. These calculations provided the detail information near the active center, but there are few calculations considering the effect of cocatalysts, supports, longer polymer chains and temperature which are the key factors in the reactions.
0169-4332r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 1 6 9 - 4 3 3 2 Ž 9 8 . 0 0 0 6 2 - 2
502
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
In order to calculate such a larger system containing the above factors and to investigate the dynamics of metallocene catalysts,molecular dynamics ŽMD. method was employed. More precisely, we investigated the interaction between the cationic active center and the counter anion as a cocatalyst, and the correlation between the substituents on Cp ring and the mobility of polymer chain.
2. Method We used the Cerius2 code to perform MD simulations. Universal Force Field ŽUFF. potential w11,12x was used to describe the interaction within the metallocene catalyst system. Seven kinds of metallocene active centers were studied. The catalyst models are illustrated in Fig. 1. PP re p re s e n ts p o ly p ro p y le n e a n d ŽŽCH 2 CHŽCH 3 ..14 CH 2 CH 3 . was used in our calculations. As a cocatalyst, ŽC 6 F5 .4 By was used. Before MD simulation, QEq charge calculations w13x were carried out to assign the atomic charge and then sufficient minimizing calculations were carried out. MD simulations were performed at constant NVT ŽT s 343 K.. The calculation investigating the inter-
action between the cationic active center and the counter anion, and that investigating the correlation between the substituents on Cp ring and the mobility of polymer chain were carried out for 50 000 and 100 000 steps, respectively, where a time step corresponds to 0.5 = 10y1 5 seconds. During the simulation all the systems are relaxed and no constraints were imposed. In order to check the UFF potential, we compared the calculated structure of SiMe 2 Cp 2 ZrCHq 3 with available experimental data w14x. The deviation of the calculated bond lengths and bond angles from the experimental values were very small, and were be˚ and 0.06 A˚ and between 4.28 and 6.68, tween 0.00 A respectively. Therefore, we confirmed the validity of UFF potential parameters used here.
3. Results and discussion First, we investigated the interaction between the . and the counter active center ŽSiMe 2 Cp 2 ZrCHq 3 y y. ŽŽ . anion C 6 F5 4 B or Cl used as cocatalysts. Since the calculation using only one initial structure seems to be unreliable, the calculation using several initial structures were carried out. Fig. 2a shows the most
Fig. 1. The models of seven metallocene cationic active centers used in our MD simulation.
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
503
. Ž . ŽŽC 6 F5 .4 By. as cocatalyst. Ža. Fig. 2. The interaction between the Ža. cationic active center ŽSiMe 2 Cp 2 ZrCHq 3 and the counter anion b shows the most stable state and Žb. shows the metastable state.
stable adsorption state, where one or two fluorines of ŽC 6 F5 .4 By are coordinated to the unsaturated coordination space. This result is consistent with the experimental results w15,16x. It was also observed that a metastable state is in existence, where ŽC 6 F5 .4 By interacts with whole active center, and moreover one or two F come closer to Si atom ŽFig. 2b.. Table 1 shows the stabilization energy due to the coordination of ŽC 6 F5 .4 By obtained from our MD calculations. The energy difference between the most stable state and the metastable state is not so large and the value is about 10 kcalrmol. Therefore, when the neighbourhood of Zr atom is more crowded with substituents on Cp ring and polymer chain, it becomes difficult for ŽC 6 F5 .4 By to access the Zr atom and the metastable state which was obtained from our calculation may become dominant. When
we used Cly as a counter anion for the comparison with ŽC 6 F5 .4 By, although Cly is not a real cocatalyst, Cly is adsorbed only to the unsaturated coordination space. The stabilization energy by the coordination of ŽC 6 F5 .4 By is about two times lower than that of Cly ŽTable 1., which indicates that the
Table 1 The stabilization energy by coordination of the counter anion to the cationic active center. These energy are obtained from our MD calculation Counter anion
Stabilization energy Žkcalrmol.
ŽC 6 F5 .4 By Žmost stable. ŽC 6 F5 .4 By Žmetastable. Cly
y41 y30 y86
Fig. 3. The locus of Si–Zr–C a angle using catalyst 5 during the simulation.
504
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
Fig. 4. The distribution histogram of Si–Zr–C a angle using catalyst 5 at the equilibrium state.
electrostatic interaction between the active center and ŽC 6 F5 .4 By is weak and ŽC 6 F5 .4 By must be labile enough to be displaced by the polymerizing monomer. We investigated the correlation between the substituents on Cp ring and the mobility of polymer chain. Fig. 3 shows a locus of Si–Zr–C a angle ŽC a : first carbon of polymer chain. using catalyst 5 during the simulation. Probably because the angle at the first stage of calculation Žabout 1258. was strained, the angle shifted to the range between 1608 and 1808 quickly and reached the equilibrium state in this range. Fig. 4 shows the distribution histogram of Si–Zr–C a angle of catalyst 5 at the equilibrium state and the range of Si–Zr–C a angle appeared with more than 2% of frequency was examined. Similarly,
the amplitudes of the fluctuation of this angle were also examined for the other catalysts from the distribution histograms like Fig. 4. The results are summarized in Table 2 with the experimental data w3x Žisotactic stereospecificity of produced polypropylene.. When we used a low isospecific and non substituted metallocene catalyst like 1, the Si–Zr–C a angle fluctuated between 1328 and 1808 Žvariation is 488., which indicates that when there is a large space around the polymer chain, polymer chain can move around easily. When we used a high isospecific and more steric substituted metallocene catalyst like 6, the variation of Si–Zr–C a angle was about 188, which indicates that polymer chain in the crowd of more steric substituents can not move around easily. Generally Table 2 shows the tendency that the higher the isotactic stereospecificity of the catalysts, the more restrained the mobility of polymer chain. In order to produce more stereospecific polymer, uniform monomer coordination has to be obtained, which is believed to be achieved by controlling the end of the polymer chain by the ligand frame of the active complex w8,10x. Our simulation results represent that there is a correlation between the mobility of the end of polymer chain, i.e., the mobility of Si–Zr–C a angle, and the substituents on Cp ring. In other words, the mobility of Si–Zr–C a angle is more restrained when a high isospecific metallocene catalyst is used. Contrastly a low isospecific metallocene catalyst does not interfere with the motion of the chain. This correlation is consistent with the isotactic stereospecificity obtained from experiments. Therefore, the investigation of the dynamics of polymer chain using the current MD model should predict the stereoregularity of various metallocene catalysts. Moreover, by extending the model to include
Table 2 The range of angle ŽSi–Zr–C a . and experimental data Žisotactic stereospecificity of produced polypropylene. using various metallocene catalysts. ŽExperimental condition: 708C, Zr:Al s 1:15 000. Metallocene
Range of Si–Zr–C a angle Žvariation. Ždegree.
Experimental data: mmmm Ž%.
1 2 3 4 5 6 7
132 ; 180 Ž48. 149 ; 177 Ž28. 159 ; 180 Ž21. 158 ; 179 Ž21. 160 ; 180 Ž20. 153 ; 171 Ž18. 150 ; 177 Ž27.
y 81.7 88.6 86.5 95.2 99.1 78.1
T. Sato et al.r Applied Surface Science 130–132 (1998) 501–505
the support, the prediction of stereoregularity of supported metallocene catalyst can also be expected. 4. Conclusion Using MD simulation, the dynamics of metallocene catalyst systems containing cocatalysts, large substituents on Cp ring and long polymer chains was investigated. One or two fluorine of ŽC 6 F5 .4 By are coordinated to the unsubstituted coordination space in the most stable state. It is observed that metastable state is in existence, where ŽC 6 F5 .4 By interacts with whole active center and moreover one or two fluorine comes closer to Si atom. By investigating the dynamics of polymer chain for various substituted metallocene catalysts, it was found that there is a correlation among the mobility of the end of polymer chain, substituents on Cp ring and the stereoregularity of polymer. Therefore, the investigation of the dynamics of polymer chain using the current MD model should predict the stereoregularity of various metallocene catalysts. For industry, the development of supported metallocene catalyst is expected and recently a lot of studies about the heterogeneous metallocene catalyst were carried out w17–27x. Experimentally, there is a difference in stereoregularity between the product synthesized in homogeneous system and that synthesized in heterogeneous system using the same active center w23–27x. This indicates that the support influences the stereoregularity. Therefore in order to investigate the effect of supports on the polymer stereoregularity, we plan to compare the dynamics of metallocene catalyst in both homogeneous and heterogeneous system. References w1x H. Sinn, W. Kaminsky, Adv. Organomet. Chem. 18 Ž1980. 99.
505
w2x W. Kaminsky, K. Kulper, H.H. Brintzinger, F.R.W.P. Wild, Angew. Chem., Int. Ed. Engl. 24 Ž1985. 507. w3x W. Spaleck, F. Kuber, A. Winter, J. Rohrmann, B. Bachmann, M. Antberg, V. Doll, E.F. Poulos, Organometallics 13 Ž1994. 954. w4x R.J. Meier, G.H.J. van Doremaele, S. Italori, F. Buda, J. Am. Chem. Soc. 116 Ž1994. 7274. w5x S. Italori, F. Buda, Macromol. Symp. 89 Ž1995. 369. w6x S. Italori, F. Buda, Molecular Physics 87 Ž1996. 801. w7x L.A. Castonguay, A.K. Rappe, J. Am. Chem. Soc. 114 Ž1992. 5832. w8x H. Kawamura-Kuribayashi, N. Koga, K. Morokuma, J. Am. Chem. Soc. 114 Ž1992. 8687. w9x T. Yoshida, N. Koga, K. Morokuma, Organometallics 14 Ž1995. 746. w10x T. Yoshida, N. Koga, K. Morokuma, Organometallics 15 Ž1996. 766. w11x A.K. Rappe, C.J. Casewit, K.S. Colwell, W.A. Goddard III, W.M. Skiff, J. Am. Chem. Soc. 114 Ž1992. 10024. w12x A.K. Rappe, K.S. Colwell, Inorg. Chem. 32 Ž1993. 3438. w13x A.K. Rappe, W.A. Goddard, J. Phys. Chem. 95 Ž1991. 3358. w14x R.F. Jordan, C.S. Bajgur, R. Willet, B. Scott, J. Am. Chem. Soc. 108 Ž1986. 7410. w15x X. Yang, C.L. Stern, T.J. Marks, Organometallics 10 Ž1991. 840. w16x L. Jia, X. Yang, C.L. Stern, T.J. Marks, Organometallics, In press. w17x K. Soga, M. Kaminaka, Macromol. Chem., Rapid Commun. 13 Ž1992. 221. w18x K. Soga, T. Shiono, H.J. Kim, Macromol. Chem. 194 Ž1993. 3499. w19x F. Langhauser, J. Kerth, M. Kersting, P. Kolle, D. Lilge, P. Muller, Die Angewandte Makromolekulare Chemie 223 Ž1994. 155. w20x K. Soga, M. Kaminaka, Macromol. Chem. Phys. 195 Ž1994. 1369. w21x K. Soga, T. Arai, H. Nozawa, T. Uozumi, Macromol. Symp. 97 Ž1995. 53. w22x P. Roos, G.B. Meier, J.J.C. Samson, G. Weickert, K.R. Westerterp, Macromol. Rapid Commun. 18 Ž1997. 319. w23x W. Kaminsky, F. Renner, Macromol. Chem., Rapid Commun. 14 Ž1993. 239. w24x K. Soga, M. Kaminaka, Macromol. Chem. 194 Ž1993. 1745. w25x K. Soga, H.J. Kim, T. Shiono, Macromol. Chem. Phys. 195 Ž1994. 3347. w26x K. Soga, T. Arai, H. Nozawa, T. Uozumi, Macromol. Rapid Commun. 16 Ž1995. 905. w27x Y.S. Ko, T.K. Han, J.W. Park, S.I. Woo, Macromol. Rapid Commun. 17 Ž1996. 769.