Photoinduced electron/energy transfer (PET)-reversible addition–fragmentation chain transfer polymerization (RAFT) and conventional photoinitiated RAFT were used to synthesize polymer networks. In this study, two different metal catalysts, namely, tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)₃) and zinc tetraphenylporphyrin (ZnTPP), were selected to generate two different catalytic pathways, one with Ir(ppy)₃ proceeding through an energy-transfer pathway and one with ZnTPP proceeding through an electron-transfer pathway. These PET-RAFT systems were contrasted against a conventional photoinitated RAFT process. Mechanically robust materials were generated. Using bulk swelling ratios and degradable cross-linkers, the homogeneity of the networks was evaluated. Especially at high primary chain length and cross-link density, the PET-RAFT systems generated more uniform networks than those made by conventional RAFT, with the electron transfer-based ZnTPP giving superior results to those of Ir(ppy)₃. The ability to deactivate radicals either by RAFT exchange or reversible coupling in PET RAFT was proposed as the mechanism that gave better control in PET-RAFT systems.

中文翻译：

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PET-RAFT 提高了聚合物网络的均匀性

光诱导电子/能量转移 (PET)-可逆加成断裂链转移聚合 (RAFT) 和传统光引发 RAFT 用于合成聚合物网络。在这项研究中，选择了两种不同的金属催化剂，即三 [2-苯基吡啶基-C2,N] 铱 (III) (Ir(ppy) ₃ ) 和四苯基卟啉锌 (ZnTPP)，以产生两种不同的催化途径，其中一种具有Ir(ppy) ₃通过能量转移途径进行，而 ZnTPP 通过电子转移途径进行。这些 PET-RAFT 系统与传统的光引发 RAFT 工艺进行了对比。产生了机械坚固的材料。使用体积溶胀比和可降解交联剂，评估网络的均匀性。特别是在高主链长度和交联密度下，PET-RAFT 系统生成的网络比传统 RAFT 生成的网络更均匀，基于电子转移的 ZnTPP 的结果优于 Ir(ppy) ₃。通过 RAFT 交换或 PET RAFT 中的可逆偶联使自由基失活的能力被提议作为在 PET-RAFT 系统中提供更好控制的机制。