Du Tianyi, Shen Boming, Dai Jieyu, Zhang Miaomiao, Chen Xingjian, Yu Peiyuan, Liu Yun
Beijing National Laboratory for Molecular Sciences, Center for Soft Matter Science and Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Department of Chemistry and Shenzhen Grubbs Institute, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, China.
J Am Chem Soc. 2023 Dec 20;145(50):27788-27799. doi: 10.1021/jacs.3c10708. Epub 2023 Nov 21.
Poly(disulfide)s are an emerging class of sulfur-containing polymers with applications in medicine, energy, and functional materials. However, the constituent dynamic covalent S-S bond is highly reactive in the presence of the sulfide (RS) anion, imposing a persistent challenge to control the polymerization. Here, we report an anion-binding approach to arrest the high reactivity of the RS chain end to control the synthesis of linear poly(disulfide)s, realizing a rapid, living ring-opening polymerization of 1,2-dithiolanes with narrow dispersity and high regioselectivity (/ ∼ 1.1, ∼ 0.85). Mechanistic studies support the formation of a thiourea-base-sulfide ternary complex as the catalytically active species during the chain propagation. Theoretical analyses reveal a synergistic catalytic model where the catalyst preorganizes the protonated base and anionic chain end to establish spatial confinement over the bound monomer, effecting the observed regioselectivity. The catalytic system is amenable to monomers with various functional groups, and semicrystalline polymers are also obtained from lipoic acid derivatives by enhancing the regioselectivity.
聚二硫化物是一类新兴的含硫聚合物，在医学、能源和功能材料领域有应用。然而，其组成的动态共价S-S键在硫化物（RS）阴离子存在下具有高反应活性，这对控制聚合反应构成了持续挑战。在此，我们报道了一种阴离子结合方法，以抑制RS链端的高反应活性，从而控制线性聚二硫化物的合成，实现了1,2-二硫戊环的快速、活性开环聚合，具有窄的分散度和高区域选择性（/ ∼ 1.1， ∼ 0.85）。机理研究支持在链增长过程中形成硫脲-碱-硫化物三元络合物作为催化活性物种。理论分析揭示了一种协同催化模型，其中催化剂预组织质子化碱和阴离子链端，以对结合的单体建立空间限制，从而实现观察到的区域选择性。该催化体系适用于具有各种官能团的单体，并且通过提高区域选择性，也可从硫辛酸衍生物获得半结晶聚合物。
