The synthesis of stereoregular aliphatic polyesters with superior (bio)degradability and recyclability has been one of the promising areas in material science, which can be achieved through the stereoselective polymerization of cyclic esters. However, it remains a long-standing challenge to achieve tacticity (isotactic and heterotactic) control of aliphatic polyesters in one catalytic system through modulation of the polymerization mechanism. Here we reported a tunable and controllable method for stereoselective polymerization of racemic n-propylglycolide (ⁿPrgl) based on the analysis of the enantiomorphic site control (ESC) and chain-end control (CEC) mechanisms in the polymerization. The enantiomorphic site control and chain-end control-dominated stereoregular polymerization processes were achieved via adjustable polymerization conditions, producing isotactic poly(ⁿPrgl) with a P_m of up to 0.88 (based on ESC) and heterotactic poly(ⁿPrgl) with a P_r of up to 0.94 (based on CEC). This understanding of ESC and CEC mechanisms might provide a compelling guidance to the design of stereoselective polymerization.

中文翻译：

---

外消旋正丙醇交酯立体选择性开环聚合的聚合物立构控制

具有优异（生物）降解性和可回收性的有规立构脂肪族聚酯的合成一直是材料科学中最有前途的领域之一，这可以通过环酯的立体选择性聚合来实现。然而，通过调节聚合机理在一个催化体系中实现脂肪族聚酯的立构规整度（全同立构和异规立构）控制仍然是一个长期存在的挑战。在这里，我们基于对聚合中对映体位点控制（ESC）和链端控制（CEC）机制的分析，报道了一种外消旋正丙基乙交酯（ⁿ Prgl）立体选择性聚合的可调且可控的方法。通过调节聚合条件，实现了以对映体位点控制和链端控制为主的立构规整聚合过程，生产出P _m高达0.88（基于ESC ）的全同立构聚（n Prgl ^）和P m 高达0.88（基于ESC）的杂规聚（ⁿ Prgl）。Pr高达 0.94（基于 CEC）_。对 ESC 和 CEC 机制的理解可能为立体选择性聚合的设计提供令人信服的指导。