Fornacon-Wood Christoph, Manjunatha Bhargav R, Stühler Merlin R, Gallizioli Cesare, Müller Carsten, Pröhm Patrick, Plajer Alex J
Intitut für Chemie und Biochemie., Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.
Nat Commun. 2023 Jul 27;14(1):4525. doi: 10.1038/s41467-023-39951-y.
CS promises easy access to degradable sulfur-rich polymers and insights into how main-group derivatisation affects polymer formation and properties, though its ring-opening copolymerisation is plagued by low linkage selectivity and small-molecule by-products. We demonstrate that a cooperative Cr(III)/K catalyst selectively delivers poly(dithiocarbonates) from CS and oxetanes while state-of-the-art strategies produce linkage scrambled polymers and heterocyclic by-products. The formal introduction of sulfur centres into the parent polycarbonates results in a net shift of the polymerisation equilibrium towards, and therefore facilitating, depolymerisation. During copolymerisation however, the catalyst enables near quantitative generation of the metastable polymers in high sequence selectivity by limiting the lifetime of alkoxide intermediates. Furthermore, linkage selectivity is key to obtain semi-crystalline materials that can be moulded into self-standing objects as well as to enable chemoselective depolymerisation into cyclic dithiocarbonates which can themselves serve as monomers in ring-opening polymerisation. Our report demonstrates the potential of cooperative catalysis to produce previously inaccessible main-group rich materials with beneficial chemical and physical properties.
环硫乙烷（CS）有望提供易于获取的可降解富硫聚合物，并深入了解主族衍生化如何影响聚合物的形成和性质，尽管其开环共聚存在连接选择性低和小分子副产物的问题。我们证明，一种协同的Cr(III)/K催化剂能从CS和氧杂环丁烷中选择性地生成聚二硫代碳酸酯，而目前的先进策略会产生连接混乱的聚合物和杂环副产物。将硫中心正式引入母体聚碳酸酯中会导致聚合平衡净向解聚方向移动，从而促进解聚。然而，在共聚过程中，该催化剂通过限制醇盐中间体的寿命，能够以高序列选择性近乎定量地生成亚稳聚合物。此外，连接选择性是获得可模塑成自立物体的半结晶材料以及实现化学选择性解聚为环状二硫代碳酸酯的关键，而环状二硫代碳酸酯本身可作为开环聚合的单体。我们的报告证明了协同催化在制备具有有益化学和物理性质的、以前难以获得的富含主族元素材料方面的潜力。
