Carboxylic-acid-initiated ring-opening polymerization (ROP) of epoxides is a fast approach to esterified polyethers which are cleavable at the termini or centers. A major challenge lies in conventional ROP methods because of the lability of ester groups formed in the initiation step. Here, we describe chemoselective ROP of epoxides from aliphatic, aromatic, and methacrylic carboxylic acids using two-component metal-free catalysts. Transesterification is clearly absent so that well-defined α-(carboxylic ester)-ω-hydroxy polyethers are generated in one step from monocarboxylic acids. The livingness of the ROP is verified despite the slow initiation mode. The ester end group can be readily cleaved from the polyether hydrolytically. An α,ω-dihydroxy poly(propylene oxide) with two central ester groups is generated from a diacid initiator and transformed in situ by the same catalyst to polyurethane which shows distinct enzymatic degradability. This study provides convenient access to α,ω-heterobifunctional polyethers with cleavable, releasable, or modifiable end groups and to biodegradable polyether-based materials.

中文翻译：

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羧酸环氧化物的化学选择性聚合：直接获得酯化聚醚和可生物降解聚氨酯

羧酸引发的环氧化物开环聚合 (ROP) 是一种在末端或中心可裂解的酯化聚醚的快速方法。一个主要的挑战在于传统的 ROP 方法，因为在引发步骤中形成的酯基团不稳定。在这里，我们描述了使用双组分无金属催化剂对脂肪族、芳香族和甲基丙烯酸羧酸的环氧化物的化学选择性 ROP。明显不存在酯交换反应，因此在一个步骤中由一元羧酸生成定义明确的α-(羧酸酯)-ω-羟基聚醚。尽管启动模式较慢，但 ROP 的活性得到了验证。酯端基可以容易地从聚醚水解裂解。一个α，通过相同的催化剂原位对聚氨酯显示出明显的酶降解性。这项研究提供了方便地获得具有可裂解、可释放或可修饰端基的 α,ω-杂双官能团聚醚和可生物降解的聚醚基材料。