Copolymerization of ethylene and isoprene initiated by metallocene catalyst

被引：1

作者：

Ali, Amjad ^{[1
,3
,4
]}

Nadeem, Muhammad ^{[2
]}

Naveed, Ahmad ^{[1
]}

Moradian, Jamile Mohammadi ^{[1
]}

Haider, Syed Najeeb-Uz-Zaman ^{[1
]}

Khan, Shahid ^{[1
]}

Bhayo, Adnan Murad ^{[5
]}

Lu, Jianwei ^{[1
]}

Ali, Rai Nauman ^{[1
]}

Ahmad, Naushad ^{[6
]}

Zhiqiang, Fan ^{[4
]}

Guo, Li ^{[1
]}

机构：

[1] School of Materials Science & Engineering, Jiangsu University, Zhenjiang

[2] School of Life Sciences, Wuchang University of Technology, Wuhan

[3] Institute of Chemistry, University of Silesia, Szkolna 9, Katowice

[4] MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou

[5] Department of Chemistry and Chemical Biology, McMaster University, Hamilton, L8S 2C8, ON

[6] Department of Chemistry, College of Science, King Saud University, Riyadh

来源：

Arabian Journal of Chemistry | 2024年 / 17卷 / 11期

关键词：

Catalyst; Cocatalyst; Ethylene; Isoprene; Metallocene; Olefin;

D O I：

10.1016/j.arabjc.2024.105989

中图分类号：

学科分类号：

摘要：

In this study, we explore the dynamic nature of metallocene catalysts during ethylene/isoprene E/IP) copolymerization, with a focus on the influence of various reaction parameters. Challenges, why do olefinic catalysts show lower activity and molecular weight (Mw) at higher temperatures and low activity with higher diene content? Firstly, we investigate the observed phenomena of decreased catalyst activity and Mw at elevated temperatures using 1.25 μmole of the metallocene. Notably, a substantial increase in active sites from 30 °C to 40 °C, reaching a peak of 89 %. Surprisingly, further temperature increments lead to a noticeable decline in active sites. At 30 °C, the active site primarily engages in the insertion of IP through 3,4 connections, with no detectable cis-1,4 or trans-1,4 connections, which suggests a lack of stereoselectivity at this temperature. At 40–50°C, cis/trans-1,4 connections and active sites are approaching a higher level. This implies a reduction in chain transfer reactions, making catalytic active sites more favorable to cis/trans-1,4 connections. Secondly, we observe a remarkable impact of IP concentration in the E/IP copolymers, active centers, and activity show stability when the amount of IP was 0.116–0.48 mol/L and then started to decline when the amount of IP 0.96 mol/L, indicating a threshold beyond which deactivation occurs. Increasing IP concentration not only reduces activity and active sites but also fails to reactivate dormant polyethylene sites. The Mw and active centers of copolymers progressively decrease with elevated IP concentration, suggesting a faster chain transfer reaction with IP compared to E. © 2024 The Author(s)

引用

共 45 条

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