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Chain Shuttle between Dual Sites of a Monomolecular Organocatalyst Enables Controlled Ring-Opening Copolymerization
Macromolecules ( IF 5.1 ) Pub Date : 2024-08-22 , DOI: 10.1021/acs.macromol.4c01561
Ximin Feng 1 , Xiaowei Geng 1 , Chengjian Zhang 1 , Xinghong Zhang 1
Affiliation  

The development of a metal-free sequence-controlled polymerization method to yield sustainable polymers is at the forefront of polymer science. Here, we demonstrate the organocatalytic sequence-controlled ring-opening copolymerization (ROCOP) of lactide (LA) and ethylene oxide (EO), which is challenging due to the large difference in polymerization reactivity between LA (ΔH ≈ −25 kJ mol–1) and EO (ΔH ≈ −95 kJ mol–1). In the ROCOP process, the multifunctional organocatalyst Cat. 2 generates dual active sites of amine-thiourea and boron, which can selectively enable LA and EO polymerization, respectively. The growing-chain shuttle between the dual sites affords poly(LA-co-EO). The polymer sequence is largely adjusted covering statistics, gradients, and blocks, clarified by reactivity ratios (by three models) and visualizations of copolymer microstructure (by Monte Carlo simulation). We also conduct an exploration of how the monomer sequence affects thermal and mechanical properties of resultant oxygen-rich copolymers. The results provide insights into organocatalytic and sequence-controlled polymerization methods.

中文翻译:


单分子有机催化剂双位点之间的链穿梭实现了受控开环共聚



开发无金属序列控制聚合方法来生产可持续聚合物处于聚合物科学的前沿。在这里,我们演示了丙交酯(LA)和环氧乙烷(EO)的有机催化序列控制开环共聚(ROCOP),由于LA之间的聚合反应活性差异很大(Δ H ≈ -25 kJ mol – 1 ) 和 EO (Δ H ≈ -95 kJ mol –1 )。在 ROCOP 工艺中,多功能有机催化剂Cat. 2产生胺-硫脲和硼的双活性位点,分别可以选择性地实现LA和EO聚合。双位点之间的生长链穿梭提供了聚(LA- co -EO)。聚合物序列在统计、梯度和嵌段方面进行了大幅调整,并通过反应率(通过三个模型)和共聚物微观结构的可视化(通过蒙特卡罗模拟)进行了澄清。我们还探索了单体序列如何影响所得富氧共聚物的热性能和机械性能。这些结果为有机催化和序列控制聚合方法提供了见解。
更新日期:2024-08-22
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