Tetrabutylammonium carbonate (TBAC) which is obtained by treating CO₂ with tetrabutylammonium hydroxide is shown to perform as an ideal difunctional initiator for the copolymerization of carbon dioxide (CO₂) and propylene oxide (PO) in the presence of triethylborane (TEB). In this system, CO₂ thus serves as the initiating moiety of its own copolymerization with epoxides when used in the form of a carbonate salt. Based on this remarkable result, mono-, tri-, and tetrafunctional ammonium carboxylate initiators and also other difunctional carboxylate initiators were synthesized and used for the synthesis of well-defined ω-hydroxyl-polycarbonates with linear and star structures. Well-defined telechelics, three- and four-armed star samples of molar mass varying from 1 kg/mol to 10 kg/mol, with around 95% carbonate content, were successfully synthesized. The structure of the obtained polycarbonate ω-polyols were characterized by ¹H NMR, MALDI-TOF, and GPC. The terminal hydroxyl functionality of polycarbonate diol was further used for polycondensation with diisocyanates to afford polyurethanes. Finally, taking TBAC as an example, the recyclability of this ammonium-based initiator is demonstrated for the preparation of polycarbonate diols.

中文翻译：

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羧酸盐作为CO ₂与环氧的无金属共聚的理想引发剂：定义明确的聚碳酸酯二醇和多元醇的合成

通过用四丁基氢氧化铵处理CO ₂而获得的碳酸四丁基铵（TBAC）已显示出是在三乙基硼烷（TEB）存在下二氧化碳（CO ₂）和环氧丙烷（PO）共聚的理想双官能引发剂。在该系统中，CO ₂当以碳酸盐的形式使用时，其因此充当其自身与环氧化物共聚的引发部分。基于这一显着结果，合成了单，三和四官能团的羧酸铵引发剂，以及其他双官能团的羧酸盐引发剂，并用于合成具有线性和星形结构的明确定义的ω-羟基聚碳酸酯。定义明确的遥测分子，摩尔质量从1kg / mol到10kg / mol的三臂和四臂星形样品已成功合成，其中碳酸盐含量约为95％。所得到的聚碳酸酯ω-多元醇的结构特征在于¹1 H NMR，MALDI-TOF和GPC。聚碳酸酯二醇的末端羟基官能度进一步用于与二异氰酸酯的缩聚反应以提供聚氨酯。最后，以TBAC为例，证明了该铵基引发剂的可回收性用于制备聚碳酸酯二醇。