The amalgamation of photoredox catalysis and reversible-deactivation radical polymerization (RDRP) has offered new avenues of controlling polymer synthesis in recent years. Additionally, the incorporation of bismuth oxide catalysts offers advantages to overcome the limitations of current endogenous catalysis. In this study, we used bismuth oxide to employ dithiocarbonyl disulfides as chain transfer agents (CTAs) in reversible addition–fragmentation chain transfer (RAFT) polymerizations. Despite using CTA precursors with a symmetric molecular structure, we show that the corresponding homo-telechelic (co)polymers propagate with asymmetric growth in one direction only. We employed this methodology to produce homo-telechelic AB diblock copolymers and ABC triblock terpolymers, which after aminolysis can undergo reversible oxidative step-growth polymerization or ring-closure to form either unusual multiblock copolymers or cyclic block copolymers.

中文翻译：

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没有“R-基团”的 RAFT：从不对称同遥爪到多嵌段逐步生长和环状嵌段共聚物

近年来，光氧化还原催化和可逆失活自由基聚合（RDRP）的结合为控制聚合物合成提供了新的途径。此外，氧化铋催化剂的加入提供了克服当前内源催化的局限性的优势。在这项研究中，我们使用氧化铋在可逆加成断裂链转移 (RAFT) 聚合中使用二硫代羰基二硫化物作为链转移剂 (CTA)。尽管使用具有对称分子结构的 CTA 前体，我们表明相应的均遥爪（共）聚合物仅在一个方向上以不对称增长传播。我们采用这种方法生产均遥爪 AB 二嵌段共聚物和 ABC 三嵌段三元共聚物，