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• Kaivalchatchawal, P
• Praserthdam, P
• Sogo, Y
• Cai, Z
• Shiono, T
• Jongsomjit, B
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• Kaivalchatchawal, P
• Praserthdam, P
• Sogo, Y
• Cai, Z
• Shiono, T
• Jongsomjit, B
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• Kaivalchatchawal, P
• Praserthdam, P
• Sogo, Y
• Cai, Z
• Shiono, T
• Jongsomjit, B

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Molecules 2011, 16(5), 4122-4130; doi:10.3390/molecules16054122

Article

The Influence of t-Butyl and Cyclododecyl Substitution on Ethylene/1-Hexene Copolymerization Using Ansa-Fluorenylamidodimethyltitanium Derivatives

Patcharaporn Kaivalchatchawal ¹ , Piyasan Praserthdam ¹ , Yuuichi Sogo ² , Zhengguo Cai ² , Takeshi Shiono ²  and Bunjerd Jongsomjit ^1,*

¹ Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand ² Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan

* Author to whom correspondence should be addressed.

Received: 9 March 2011; in revised form: 9 May 2011 / Accepted: 12 May 2011 / Published: 19 May 2011

Download PDF Full-Text [399 KB, uploaded 19 May 2011 14:34 CEST]

Abstract: In the present study, copolymerization of ethylene and 1-hexene was conducted with a series of ansa-fluorenylamidodimethyltitanium complexes, including [t-BuNSiMe₂Flu]TiMe₂ (complex 1), [cyclododecylNSiMe₂Flu]TiMe₂ (complex 2) and [t-BuNSiMe₂(2,7-t-Bu₂Flu)]TiMe₂ (complex 3), activated by MMAO. The effect of these catalysts on catalytic behavior, namely activity, molecular weight and monomer reactivity ratios, has been investigated. The results showed that all of them acted by a single site polymerization mechanism and the molecular weight distribution is independent of catalyst structure. Based on the study, it revealed that the introduction of a t-butyl at the 2,7 position on the fluorenyl ligand is able to enhance both catalytic activity and copolymer molecular weight more than introducing a cyclododecyl on the amine, which is probably associated with the electronic effect exerted by the t-butyl substituent. The comonomer incorporation content was controllable over a wide range by adjusting the comonomer feed ratio. Moreover, referring to monomer reactivity ratio exploration, it seems that the substitution on the ansa-fluorenylamidodimethyltitanium complex tends to hinder the insertion of 1-hexene into the polymer chain, leading to the highest 1-hexene content for traditional complex 1.

Keywords: polymer synthesis; catalytic synthesis; polyolefins; metallocene catalyst; CGC catalyst

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