学 位 記 番 号 理工博 第

氏 名 ジャオ

ウェイジェン

所 属 理工学研究科 分子物質化学専攻 学 位 の 種 類 博士（理学）

学 位 記 番 号 理工博 第

号 学位授与の日付 平成

年

月

日 課程・論文の別 学位規則第４条第

項該当

学 位 論 文 題 名

ハーフチタノセン触媒による新規環状オレフィン共重合体の合成

（英文）

論 文 審 査 委 員 主査 教 授 野村 琴広 委員 教 授 清水 敏夫 委員 准教授 稲垣 昭子

准教授 西長 亨

委員

教授 塩野 毅

広島大学

【論文の内容の要旨】

Summary

Cyclic olefin copolymers (COCs) and cyclic olefin polymers (COPs) have been considered as promising amorphous materials, due to their unique combination of high transparency in the UV-Vis region along with humidity-, heat-resistance (high glass transition temperature, Tg). Considerable attention has been paid to development of efficient catalysts for synthesis of new copolymers (with high CO contents, with α-olefin etc.). Modified nonbridged half-titanocenes containing anionic donor ligands, Cp’TiX2(Y) (Cp’: cyclopentadienyl group; X: halogen, alkyl etc.; Y: anionic donor ligand such as aryloxo, ketimide, phosphinimide etc.)¹ have been considered as promising candidates as new efficient catalysts. The aryloxo- or ketimide- modified half-titanocenes were known to exhibit both high catalytic activities and efficient comonomer incorporations for copolymerization of ethylene with cyclic olefins [norbornene (NBE),^2-4 cyclopentene,⁵ cyclohexene⁶ etc.] in the presence of methylaluminoxane (MAO) cocatalyst. However, reports concerning efficient incorporation of α-olefin in the copolymerization with cyclic olefin have been limited so far.

In this Ph.D. thesis, results concerning synthesis of new cyclic olefin copolymers using half-titanocene catalysts, including factors affecting the ligand effect, have been described. The thesis consists of the following three chapters: (i) synthesis of new COCs by copolymerization of

CO with α-olefins,⁷ (ii) synthesis of new COCs by incorporation of sterically encumbered α-olefins,⁸ (iii) effect of ligand for efficient cyclic olefin copolymerization using half-titanocene catalysts.⁹

Results and Discussion

1. Copolymerizations of norbornene, tetracyclododecene with α-olefins: Efficient synthesis of highly transparent, thermal resistance polymers.

Norbornene (NBE), tetracyclododecene (TCD) copolymerizations with α-olefins using nonbridged half-titanocenes, Cp’TiCl2(N=C^tBu2), [Cp’= ^tBuC5H4 (1), C5H5 (2, Cp)], linked half-titanocene, [Me2Si(C5Me4)(N^tBu)]TiCl2 (3), ordinary metallocenes, [Et(indenyl)2]ZrCl2 (4), Cp2ZrCl2 (5), were explored in the presence of MAO cocatalyst. Copolymerizations of NBE with 1-hexene (HX) by 1,2 – MAO catalysts proceed with high catalytic activities, affording high molecular weight copolymers with uniform compositions confirmed by DSC theromograms.

Complex 2 showed >10 times higher catalytic activities and better NBE incorporation than 1 under the same conditions. The activity increased upon increasing the NBE concentration charged, and the NBE contents were modified by varying the NBE/olefin feed molar ratio. Linear correlations between the Tg values and NBE contents in the resultant poly(NBE-co-α-olefin)s were observed, and the Tg values were affected by α-olefin employed. The NBE incorporations were not affected by nature of α-olefin employed. This is the first example of synthesis of various random copolymers, poly(NBE-co-α-olefin)s, with efficient NBE incorporation.⁷

The copolymerization of TCD with α-olefin by the Cp-ketimide analogue (2) afforded the copolymers with unimodal molecular weight distributions, uniform compositions confirmed by DSC thermogram. In contrast, 1 showed the low activity, and the copolymerization of TCD with 1-octene by 3, 4 and 5 afforded negligible amount of oligomers. The resultant copolymers possessed rather high molecular weights with unimodal molecular weight distributions, and the Tg

values in poly(TCD-co-α-olefin)s were higher than those in poly(NBE-co-α-olefin)s with similar CO contents. The TCD incorporation in the copolymerization by 2 – MAO catalyst was not strongly affected by kind of α-olefin employed (HX, OC, DD), and relatively linear correlations between TCD contents in the copolymers and TCD/α-olefin feed molar ratios were observed. The copolymer showed high transparency as thin film. Microstructure analysis in the resultant poly(TCD-co-α-olefin)s by ¹³C NMR spectra assumed in high certainty that the TCD incorporations are random (isolated, alternating, and repeated TCD incorporations). This is the first demonstration of copolymerization of TCD with α-olefin in an efficient manner.

2. Synthesis of new cyclic olefin copolymers by incorporation of sterically encumbered olefins On the basis of reported results in the ethylene copolymerization with cyclohexene (CHE),⁶ cyclopentene (CPE),⁵ and the above results,⁷ possibilities for synthesis of new copolymers by

incorporation of various monomers were explored by using the aryloxo-, ketimide-modified half-titanocenes, Cp’TiCl2(Y) [Y: N=C^tBu, Cp’= ^tBuC5H4 (1), C5Me5 (Cp*, 2); Y: O-2,6-ⁱPr2C6H3, Cp’= Cp* (6), 1,2,4-Me3C5H2 (7), ^tBuC5H4 (8), Cp (9), indenyl (10)].

In the copolymerization of NBE with vinylcylohexane (VCH), vinyltrimethylsilane (VTMS), and allyltimerthylsilane (ATMS), both the substituent on Cp’ and anionic donor ligands affected the polymerization behavior; the resultant copolymers generally possessed rather molecular weights but with unimodal molecular distributions as well as uniform compositions confirmed by their DSC thermograms. Complex 7 only showed CHE incorporation in the copolymerization with 1-hexene, whereas the other complexes showed negligible CHE incorporations under the same conditions.

3. Effect of ligand for efficient cyclic olefin copolymerization using half-titanocene catalysts.

Ethylene/NBE copolymerizations using half-titanocenes containing chlorinated phenoxy ligands, Cp’TiCl2(Y) [Cp’: Cp, indenyl; Y: O-2,6-Cl2C6H3, O-2,4,6-Cl3C6H2, O-C6Cl5] have been explored in the presence of MAO.⁹

The Cp analogue (11-13) exhibited both higher catalytic activities and more efficient norbornene (NBE) incorporation in ethylene/NBE copolymerization than (indenyl)TiCl2(O-2,6-ⁱPr2C6H3) (10),^2a,b which exhibited better NBE incorporation than [Me2Si(C5Me4)(N^tBu)]TiCl2 (CGC), [Me2Si(indenyl)2]ZrCl2 under the same conditions.³ These complexes (11-13) also showed better NBE incorporation than CpTiCl2(N=C^tBu2) (2), which was known as the most efficient NBE incorporation in the copolymerization under the same conditions.³ The resultant polymers were high molecular weight poly(ethylene-co-NBE)s with uniform molecular weight distributions, and their compositions are also uniform confirmed by DSC thermograms; a linear relationship between the NBE content and the glass transition temperatures (Tg) were observed. On the basis of ¹³C NMR spectra, the resultant copolymers possess microstructures with random NBE incorporation including NBE repeat units without stereo-regularity.

Conclusion

The results through this research present that precise syntheses of new cyclic olefin copolymers (COCs) that cannot be prepared by conventional catalysts have been achieved by using nonbridged half-titanocene catalysts. The information should be important not only for synthesis of new COCs with specified functions, but also for design of more effective catalysts for the purpose.

References

[1] (a) Nomura, K.; Liu, J.; Padmanabhan, S.; Kitiyanan, B. J. Mol. Catal. A: Chemical 2007, 267, 1. (b) Nomura, K. Dalton Trans. 2009, 8811. (c) Nomura, K.; Liu, J. Dalton Trans. 2011, 40, 7666.

[2] (a) Nomura, K.; Tsubota, M.; Fujiki, M. Macromolecules 2003, 36, 3797. (b) Wang, W.; Tanaka, T.;

Tsubota, M.; Fujiki, M.; Yamanaka, S.; Nomura, K. Adv. Synth. Catal. 2005, 347, 433.

[3] Nomura, K.; Wang, W.; Fujiki, M.; Liu, J. Chem. Commun. 2006, 2659.

[4] (a) Nomura, K.; Fukuda, H. et al. Macromolecules 2011, 44, 1986. (b) Apisuk, W.; Trambitas, A. G.;

Kitiyanan, B.; Tamm, M.; Nomura, K. J. Polym. Sci. Part A: Polym. Chem. 2013, 51, 2575.

[5] Liu, J.; Nomura, K. Adv. Synth. Catal. 2007, 349, 2235.

[6] Wang, W.; Fujiki, M.; Nomura, K. J. Am. Chem. Soc. 2005, 127, 4582.

[7] Zhao, W.; Nomura, K. Macromolecule 2016, 49, 59.

[8] Zhao, W.; Nomura, K. ms. in preparation.

[9] Zhao, W.; Yan, Q.; Tsutsumi, K.; Nomura, K. Organometallics, in press. DOI:

10.1021/acs.organomet.6b00242.