Renewable methylene butyrolactones, such as γ-methyl-α-methylene-γ-butyrolactone (MMBL) and α-methylene-γ-butyrolactone (MBL), have received particular attention due to their high reactivity and enhanced polymer performance. However, challenges still remain in the development of a living/controlled polymerization strategy for these renewable monomers. This contribution reports an effective frustrated Lewis pair consisting of a strong organophosphorus superbase and a sterically encumbered but modestly strong organoaluminum Lewis acid to rapidly polymerize (M)MBL into polymers with a predicted molecular weight (M_n up to 195 kg mol⁻¹) and narrow molecular weight distribution (MWD as low as 1.04), thus affording high to near quantitative initiation efficiency. The livingness of MMBL polymerization catalyzed by the P(NIⁱPr)Ph₂/(BHT)₂AlⁱBu FLP was confirmed by successful chain extension experiments and the formation of well-defined copolymers. Besides, this LPP strategy also enabled the synthesis of the diblock copolymers PMMA-b-PMMBL and PEEMA-b-PMMBL by using methacrylate as a comonomer. Furthermore, a kinetic study coupled with the characterization of the active zwitterionic species led to the bimolecular, activated monomer propagation mechanism proposed for (M)MBL polymerization catalyzed by such an FLP system.

中文翻译：

---

受挫路易斯对介导的天然可再生丁内酯基亚乙烯基的活性聚合

可再生亚甲基丁内酯，如γ-甲基-α-亚甲基-γ-丁内酯（MMBL）和α-亚甲基-γ-丁内酯（MBL），因其高反应性和增强的聚合物性能而受到特别关注。然而，在为这些可再生单体开发活性/可控聚合策略方面仍然存在挑战。该贡献报告了一种有效的受挫路易斯对，由强有机磷超强碱和空间受阻但强度适中的有机铝路易斯酸组成，可将 (M)MBL 快速聚合成具有预测分子量的聚合物 ( M _n高达 195 kg mol ^-1) 和窄的分子量分布（MWD 低至 1.04），从而提供高到接近定量的引发效率。由 P(NI ⁱ Pr)Ph ₂ /(BHT) ₂ Al ⁱ Bu FLP催化的 MMBL 聚合的活性通过成功的扩链实验和明确定义的共聚物的形成得到证实。此外，这种 LPP 策略还能够合成二嵌段共聚物 PMMA- b -PMMBL 和 PEEMA- b-PMMBL 使用甲基丙烯酸酯作为共聚单体。此外，动力学研究与活性两性离子物种的表征相结合，导致了为由这种 FLP 系统催化的 (M)MBL 聚合提出的双分子活化单体传播机制。