While enabling precise control and well-defined molecular weights in polymer synthesis, photocatalyzed reversible deactivation radical polymerization (photo-RDRP) suffers from slow kinetics, limiting its broader application in advanced manufacturing. Despite a decade of research on photocatalyst design, progress in significantly improving the kinetics of photo-RDRP remains insufficient. In contrast, the role of the initiator in photo-RDRP is often overlooked, especially in photoinduced electron/energy transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization, where the RAFT agent serves as both the initiator and chain transfer agent. In this work, we first designed and synthesized a new RAFT agent with an indazole Z group (InZ) for highly efficient PET-RAFT polymerization under irradiation. This strongly electron-donating Z group accelerates initiation by facilitating π* → σ* charge transfer in PET-RAFT systems. Compared to the commonly used trithiocarbonates in PET-RAFT polymerization, utilization of InZ improved polymerization rates significantly by 2.7-fold. Additionally, we discovered a new efficient photocatalyst (PC) in PET-RAFT polymerization, i.e., zinc 5,10,15,20-tetra(naphthalen-2-yl)porphyrin (ZnTNP), through experimental screening of various zinc porphyrin derivates. This ZnTNP/InZ system exhibits precise temporal and molecular weight control in the course of polymerization, being compatible with a broad range of acrylates and acrylamides and exhibiting good oxygen tolerance. Importantly, InZ may inspire further development of high-performance RAFT agents for PET-RAFT polymerization.

中文翻译：

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新型吲唑修饰 RAFT 试剂的设计与合成，用于高效 PET-RAFT 聚合

虽然光催化可逆失活自由基聚合（photo-RDRP）能够在聚合物合成中实现精确控制和明确的分子量，但其动力学缓慢，限制了其在先进制造中的更广泛应用。尽管对光催化剂设计的研究已经进行了十年，但在显着改善光-RDRP动力学方面取得的进展仍然不足。相反，引发剂在光-RDRP中的作用常常被忽视，特别是在光诱导电子/能量转移可逆加成-断裂链转移（PET-RAFT）聚合中，RAFT剂既充当引发剂又充当链转移剂。在这项工作中，我们首先设计并合成了一种具有吲唑Z基团（InZ）的新型RAFT试剂，用于在辐照下高效进行PET-RAFT聚合。这种强电子供给 Z 基团通过促进 PET-RAFT 系统中的 π* → σ* 电荷转移来加速引发。与 PET-RAFT 聚合中常用的三硫代碳酸酯相比，InZ 的使用使聚合速率显着提高了 2.7 倍。此外，我们通过对各种锌卟啉衍生物的实验筛选，发现了一种新型高效PET-RAFT聚合光催化剂（PC），即5,10,15,20-四（萘-2-基）卟啉锌（ZnTNP）。该ZnTNP/InZ体系在聚合过程中表现出精确的时间和分子量控制，与多种丙烯酸酯和丙烯酰胺相容，并表现出良好的耐氧性。重要的是，InZ 可能会激发用于 PET-RAFT 聚合的高性能 RAFT 试剂的进一步开发。