Combining Metal-Free and Metal-Mediated Ring-Opening Metathesis Polymerization for Efficient Synthesis of Bottlebrush Polymers.

IF 5.1 Q1 POLYMER SCIENCE

ACS Macro Letters Pub Date : 2025-06-30 DOI:10.1021/acsmacrolett.5c00300

Margaret E Tetzloff,Andrew J Boydston

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引用次数: 0

Abstract

Metal-mediated ring-opening metathesis polymerization (ROMP) is a common tool used to synthesize the backbone of bottlebrush polymers by a graft-through approach. However, examples of ROMP oligomers or polymers as macromolecular side chains are limited due in part to the challenges associated with preparing a macromonomer via the same polymerization mechanism as the one used to create the main chain. Accordingly, installation of polymerizable units onto macromonomers produced via ROMP has been achieved in a multistep fashion. In such cases, one metal initiator is used in the preparation of each macromonomer, thus constituting an overall usage of the metal complex that is 1:1 with repeat units in the final bottlebrush polymer product. By leveraging the modularity of organic initiators in metal-free ROMP (MF-ROMP), as well as the differences in monomer selectivities between metal-mediated ROMP and MF-ROMP, we demonstrate a uniquely efficient and low-metal-use route to bottlebrush polymers. Specifically, we found that norbornene imide-functionalized vinyl ether initiators were successful in MF-ROMP to produce macromonomers from tetracyclododecene without compromising the norbornene imide unit. Subsequent metal-mediated graft-through ROMP of the norbornene imide chain end using Grubbs' third-generation catalyst then produced high-molecular-weight bottlebrush copolymers. We report the synthetic methods for this sequential ROMP-ROMP approach, comparative analyses for endo- and exo-isomers of the macromonomers, and thermal characterization of the bottlebrush polymers.

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无金属与金属介导开环复聚相结合高效合成瓶刷聚合物。

金属介导开环复分解聚合（ROMP）是一种常用的通过接枝方法合成瓶刷聚合物骨架的方法。然而，ROMP低聚物或聚合物作为大分子侧链的例子是有限的，部分原因是通过与创建主链相同的聚合机制制备大分子单体所面临的挑战。因此，将可聚合单元安装到通过ROMP生产的大单体上已经以多步骤的方式实现。在这种情况下，在制备每个大单体时使用一种金属引发剂，从而在最终的瓶刷聚合物产品中构成金属配合物与重复单元的总体使用量为1:1。通过利用无金属ROMP （MF-ROMP）中有机引发剂的模块化，以及金属介导的ROMP和MF-ROMP之间单体选择性的差异，我们展示了一种独特的高效和低金属使用的瓶刷聚合物路线。具体来说，我们发现降冰片烯酰亚胺功能化的乙烯醚引发剂在MF-ROMP中成功地从四环十二烯生成了大分子单体，而不影响降冰片烯酰亚胺单元。随后，使用Grubbs的第三代催化剂对降冰片烯亚胺链端进行金属介导的ROMP接枝，从而产生了高分子量的瓶刷共聚物。我们报道了这种顺序ROMP-ROMP方法的合成方法，对大单体的内异构体和外异构体的比较分析，以及瓶刷聚合物的热表征。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Macro Letters 化学-

CiteScore

10.40

自引率

3.40%

发文量

209

审稿时长

1 months

期刊介绍： ACS Macro Letters publishes research in all areas of contemporary soft matter science in which macromolecules play a key role, including nanotechnology, self-assembly, supramolecular chemistry, biomaterials, energy generation and storage, and renewable/sustainable materials. Submissions to ACS Macro Letters should justify clearly the rapid disclosure of the key elements of the study. The scope of the journal includes high-impact research of broad interest in all areas of polymer science and engineering, including cross-disciplinary research that interfaces with polymer science. With the launch of ACS Macro Letters, all Communications that were formerly published in Macromolecules and Biomacromolecules will be published as Letters in ACS Macro Letters.