The development of next-generation materials is coupled with the ability to predictably and precisely synthesize polymers with well-defined structures and architectures. In this regard, the discovery of synthetic strategies that allow on demand control over monomer connectivity during polymerization would provide access to complex structures in a modular fashion and remains a grand challenge in polymer chemistry. In this Article, we report a method where monomer selectivity is controlled during the polymerization by the application of two orthogonal stimuli. Specifically, we developed a cationic polymerization where polymer chain growth is controlled by a chemical stimulus and paired it with a compatible photocontrolled radical polymerization. By alternating the application of the chemical and photochemical stimuli the incorporation of vinyl ethers and acrylates could be dictated by switching between cationic and radical polymerization mechanisms, respectively. This enables the synthesis of multiblock copolymers where each block length is governed by the amount of time a stimulus is applied, and the quantity of blocks is determined by the number of times the two stimuli are toggled. This new method allows on demand control over polymer structure with external influences and highlights the potential for using stimuli-controlled polymerizations to access novel materials.

中文翻译：

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正交刺激下聚合机制和单体选择性的按需切换。

下一代材料的开发与可预测和精确合成具有明确结构和架构的聚合物的能力相结合。在这方面，发现允许在聚合过程中按需控制单体连接性的合成策略将以模块化方式提供对复杂结构的访问，并且仍然是聚合物化学中的巨大挑战。在本文中，我们报告了一种通过应用两个正交刺激来控制聚合过程中单体选择性的方法。具体来说，我们开发了一种阳离子聚合，其中聚合物链的增长由化学刺激控制，并将其与兼容的光控自由基聚合配对。通过交替施加化学和光化学刺激，可以分别通过阳离子和自由基聚合机制之间的切换来控制乙烯基醚和丙烯酸酯的掺入。这使得能够合成多嵌段共聚物，其中每个嵌段长度由施加刺激的时间量决定，并且嵌段的数量由两个刺激切换的次数决定。这种新方法允许在外部影响下按需控制聚合物结构，并凸显了使用刺激控制聚合来获取新型材料的潜力。