Fast Living Polymerization and Helix-Sense-Selective Polymerization of Diazoacetates Using Air-Stable Palladium(II) Catalysts
Fast Living Polymerization and Helix-Sense-Selective Polymerization of Diazoacetates Using Air-Stable Palladium(II) Catalysts
复制标题
使用空气稳定钯 (II) 催化剂进行重氮乙酸酯的快速活性聚合和螺旋选择性聚合
DOI：
10.1021/jacs.8b11628
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发表时间：
2018-12-19
影响因子：
15
通讯作者：
Wu, Zong-Quan
中科院分区：
文献类型：
--
作者：
Chu, Jia-Hong;Xu, Xun-Hui;Wu, Zong-Quan
在这项工作中，设计并制备了带有二齿膦配体的空气稳定钯(II)催化剂，该催化剂可以在温和条件下引发各种重氮乙酸酯单体的快速、活性聚合。聚合以高产率提供了具有受控分子量 (M(n)s) 和窄分子量分布 (M-w/M(n)s) 的所需聚合物。分离出的聚合物的M(n)s与单体与催化剂的初始进料比线性相关，证实了聚合的活性/受控方式。 M-n 也随着单体转化率线性增加，并且所有分离的聚合物都表现出窄的 M-w/M(n)s。聚合反应相对较快，几分钟内即可完成。这种快速活性聚合方法可适用于各种重氮乙酸酯单体在各种有机溶剂中在室温下在空气中。利用其活性特性，我们通过扩链反应轻松制备了一系列嵌段共聚物。通过这种方法合成的两亲性嵌段共聚物表现出有趣的自组装特性。此外，通过带有手性二齿膦配体的 Pd(II) 催化剂聚合非手性大体积重氮乙酸盐，由于形成主链的主要单手螺旋，导致形成具有高光学活性的聚合物。聚合物的螺旋方向由 Pd(II) 催化剂的手性决定。
In this work, air-stable palladium(II) catalysts bearing bidentate phosphine ligands were designed and prepared, which could initiate fast and living polymerizations of various diazoacetate monomers under mild conditions. The polymerization afforded the desired polymers in high yields with controlled molecular weights (M(n)s) and narrow molecular weight distributions (M-w/M(n)s). The M(n)s of the isolated polymers were linearly correlated to the initial feed ratios of monomer to catalyst, confirming the living/controlled manner of the polymerizations. The M-n also increased linearly with the monomer conversion, and all of the isolated polymers showed narrow M-w/M(n)s. The polymerization was relatively fast and could be accomplished within several minutes. Such fast living polymerization method can be applied to a wide range of diazoacetate monomers in various organic solvents at room temperature in air. Taking advantage of the living nature, we facilely prepared a series of block copolymers through chain extension reactions. The amphiphilic block copolymers synthesized by this method exhibited interesting self-assembly properties. Moreover, polymerization of achiral bulky diazoacetate by Pd(II) catalysts bearing a chiral bidentate phosphine ligand leads to the formation of polymers with high optical activity due to the formation of the predominantly one-handed helix of the main chain. The helix sense of the polymers was determined by the chirality of the Pd(II) catalysts.