GSK Carbon Neutral Laboratories for Sustainable Chemistry, University of Nottingham, Triumph Road, Nottingham NG7 2TU, U.K.
School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
J Am Chem Soc. 2020 May 6;142(18):8136-8141. doi: 10.1021/jacs.0c03520. Epub 2020 Apr 24.
Aryl isocyanates are introduced as comonomers for ring-opening copolymerization (ROCOP) with epoxides. Informed by studies of reaction kinetics, we show that divergent sequence selectivity for AB- and ABB-type copolymers can be achieved with a single dimagnesium catalyst. The resulting materials respectively constitute a new class of polyurethanes (PUs) and a new class of materials featuring an unprecedented backbone structure, the polyallophanates (PAs). The successful use of isocyanate comonomers in this way marks a new direction for the field of ROCOP while providing distinct opportunities for expansion of PU structural diversity. Specifically, the methodology reported herein delivers PUs featuring fully substituted (tertiary) carbamyl nitrogen atoms, a structural motif that is almost inaccessible via extant polymerization strategies. Thus, in one step from commercially available comonomers, our methodology expands the scope of ROCOP and gives access to diverse materials featuring both privileged (PU) and unexplored (PA) microstructures.
芳基异氰酸酯被引入作为开环共聚（ROCOP）与环氧化物的共聚单体。根据反应动力学的研究，我们表明，具有 AB 和 ABB 型结构的嵌段共聚物可以通过单一的二镁催化剂实现不同的序列选择性。所得材料分别构成了一类新的聚氨酯（PU）和一类具有前所未有的骨架结构的新型材料，即聚全缩醛（PA）。以这种方式成功地使用异氰酸酯共聚单体为 ROCOP 领域开辟了新的方向，同时为 PU 结构多样性的扩展提供了独特的机会。具体来说，本文报道的方法提供了具有完全取代（叔）氨基甲酰氮原子的 PU，这是一种通过现有聚合策略几乎无法获得的结构基序。因此，通过商业上可获得的共聚单体，我们的方法扩展了 ROCOP 的范围，并获得了具有特权（PU）和未开发（PA）微观结构的各种材料。
