School of Materials Science & Engineering, Jiangsu University, Zhenjiang, 212013, PR China; Institute of Chemistry, University of Silesia, Szkolna 9, Katowice, 40-600, Poland; MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, PR China.
School of Materials Science & Engineering, Jiangsu University, Zhenjiang, 212013, PR China.
Chemosphere. 2024 Jan;347:140700. doi: 10.1016/j.chemosphere.2023.140700. Epub 2023 Nov 15.
The copolymerization of ethylene (E) with isoprene (Ip) was performed catalyzed by a symmetrical catalyst exhibiting a silicon bridge [rac-MeSi(2-Me-4-Ph-Ind)ZrCl with the combination of borate/TIBA activator. The effect of cocatalyst, Ip concentration, and polymerization temperature on the activity, molecular weight (Mw), distribution (MWD), comonomer composition, chain structure (regio- and stereoselectivity), and resulting side reactions were logically addressed. Gel-permeation chromatography (GPC) was used to characterize the Mw and polydispersity, while nuclear magnetic resonance (NMR) was employed for the chain structure of the polymers. The catalytic activity was significantly lower by increasing the Ip concentration in the feed, and the isoprene content in resulting polymers was lower under the reaction condition, leading to higher activity. Insertion of isoprene units in polymer structure demonstrates the higher regioselectivity for the 3,4 connections than the 1,4 connections and is expected to be a high-resistance polymer against acids. The MWD presented monomodal even with a higher concentration (1.44 mol/L) and did not appear as low Mw peaks of Ip. The Mw was higher with a broader MWD when purely TIBA was used as a cocatalyst, and it significantly reduced and presented a narrowed MWD with TEA in the cocatalyst. The higher efficiency of the catalyst for the higher insertion of Ip (C=C double bond) effectively modifies the polymer backbone. It is expected to be a promising candidate for easily degradable and favorable solutions for solving environmental problems caused by PE. wastes.
乙烯（E）与异戊二烯（Ip）的共聚是由具有硅桥的对称催化剂催化的[rac-MeSi(2-Me-4-Ph-Ind)ZrCl]，与硼酸盐/TIBA 活化剂组合。合理地研究了助催化剂、Ip 浓度和聚合温度对活性、分子量（Mw）、分布（MWD）、共聚单体组成、链结构（区域和立体选择性）以及产生的副反应的影响。凝胶渗透色谱（GPC）用于表征 Mw 和多分散性，而核磁共振（NMR）用于聚合物的链结构。进料中 Ip 浓度的增加会显著降低催化活性，反应条件下聚合物中的异戊二烯含量较低，导致活性较高。异戊二烯单元在聚合物结构中的插入表明 3,4 连接的区域选择性高于 1,4 连接，预计对酸具有较高的抗阻性。MWD 即使在较高浓度（1.44 mol/L）下也呈现单峰，而不会出现 Ip 的低 Mw 峰。当纯粹使用 TIBA 作为助催化剂时，Mw 较高且 MWD 较宽，当 TEA 作为助催化剂时，Mw 显著降低且 MWD 变窄。催化剂对 Ip（C=C 双键）的高插入效率有效地修饰了聚合物主链。它有望成为一种有前途的候选材料，可用于解决由 PE 废料引起的环境问题的易降解和有利解决方案。
