化学
聚丁二烯
部分
聚合
链式转移
烷基转移
高分子化学
烷基化
表面改性
筑地反应
阴离子加成聚合
烯丙基重排
催化作用
组合化学
自由基聚合
有机化学
共聚物
聚合物
物理化学
作者
Pibo Liu,Xiaoni Yang,He Lin,Songbo Zhang,Yanming Hu,Guangyuan Zhou,Nikos Hadjichristidis
标识
DOI:10.1002/anie.202317494
摘要
Abstract There are still challenges in the preparation of difunctional stereoregular polydienes, especially for the construction of initiating chain‐end functionalization. Coordinative chain transfer polymerization (CCTP) provides a way to achieve the goal but usually requires sophisticated functionalized catalysts as well as expensive chain transfer agents (CTAs). In this work, heteroleptic aluminum with oligo(dienyl) substituents (oligo‐Al agents) were readily prepared by living anionic polymerization (LAP) technique. The oligo‐Al agents used in Nd‐mediated CCTPs of dienes exhibit highly selective alkylation and transalkylation features. Kinetics and transfer efficiency studies using 1 H NMR, 13 C NMR, 1 H‐ 13 C HSQC, and Dosy NMR analyses revealed that the resulting polydienes possess substituents at the initiating chain‐end that have transferred from the oligo‐Al agents. The functionalization efficiency of the initiating chain‐end is up to 99 %, and the molar mass regulation efficiency of heteroleptic aluminum is higher than that of the traditional CTA Al i Bu 2 H (0.608 vs. 0.410). Based on the experimental results and density functional theory (DFT) calculations, we propose a mechanism in which allylic‐Al acts as an efficient alkylating moiety in catalyst preformation and also as an effective transfer agent in polymerization. Taking advantage of these features, di‐functionalized polyisoprene, polybutadiene, and poly(isoprene‐co‐butadiene) can be facilely synthesized.
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