Selective or living organopolymerization of a six-five bicyclic lactone to produce fully recyclable polyesters
Selective or living organopolymerization of a six-five bicyclic lactone to produce fully recyclable polyesters
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DOI：
10.1039/c9py00190e
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发表时间：
2019-06-21
影响因子：
4.6
通讯作者：
Chen, Eugene Y. -X.
中科院分区：
文献类型：
--
作者：
Cywar, Robin M.;Zhu, Jian-Bo;Chen, Eugene Y. -X.
六五双环内酯、4,5-反式环己基稠合γ-丁内酯 (4,5-T6GBL) 的有机催化开环聚合 (O-ROP) 可以具有拓扑选择性或在室温下存在，具体取决于催化剂结构。 (硫)脲[(T)U]和有机碱基对的筛选揭示了该单体的独特反应性趋势以及最活跃的催化剂对，这些催化剂对在商业上用于以活性方式生产相对高分子量（M-n高达106 kDa）、低分散性（D = 1.04）线性聚（4,5-T6GBL）。在纯条件下使用 TU/KOMe 有机/无机混合对的 ROP 产生了具有更高分子量的聚 (4,5-T6GBL)（M-n = 215 kDa，D = 1.04）。与金属催化体系相比，(T)U-碱基对表现出竞争动力学并达到了更高的单体转化率，并且它们的反应可以在空气中进行。此外，所得聚合物需要较少的纯化来生产具有较高起始分解温度的材料。 (T)U-碱基对仅对线性聚合具有选择性，而三氮杂双环癸烯可以催化聚合和（定量）解聚过程，具体取决于反应条件。通过 N-杂环卡宾介导的两性离子 O-ROP 选择性形成 M-n = 41-72 kDa 的环状聚合物。
Organocatalyzed ring-opening polymerization (O-ROP) of a six-five bicyclic lactone, 4,5-trans-cyclohexyl-fused gamma-butyrolactone (4,5-T6GBL), can be topologically selective or living at room temperature, depending on catalyst structure. A screening of (thio)urea [(T)U] and organic base pairs revealed unique trends in reactivity for this monomer as well as the most active catalyst pairs, which were employed as received commercially to produce relatively high molecular weight (M-n up to 106 kDa), low dispersity (D = 1.04) linear poly(4,5-T6GBL) in a living fashion. The ROP using a hybrid organic/inorganic pair of TU/KOMe in neat conditions led to poly(4,5-T6GBL) with even higher molecular weight (M-n = 215 kDa, D = 1.04). In comparison to the metal-catalyzed system, (T)U-base pairs exhibited competitive kinetics and reached higher monomer conversions, and their reactions can be performed in air. In addition, the resulting polymers required less purification to produce materials with higher onset decomposition temperature. (T)U-base pairs were selective towards linear polymerization only, whereas triazabicyclodecene can catalyze both polymerization and (quantitative) depolymerization processes, depending on reaction conditions. Cyclic polymers with M-n = 41-72 kDa were selectively formed via N-heterocyclic carbene-mediated zwitterionic O-ROP.