The reactivity of bifunctional borinane-based mono-ammonium salts has previously been demonstrated in various polymerization processes, including ring-opening polymerization (ROP) of epoxides and copolymerization with CO₂ or anhydrides. In this study, three bifunctional borinane-based multi-ammonium salts (N⁺/B) B, C and D (B₈N₃(C₆)Br₃; B₈N₃(C₂)Br₃; B₁₀N₄(C₂)Br₄) were synthesized with varying B/N ratios and linker lengths between two ammoniums, along with a monoammonium bifunctional salt, catalyst A, B₃NBr, used as a reference. The polymerization activities of these catalysts which were essentially used as initiators were evaluated in ROP of propylene oxide (PO), epichlorohydrin (ECH), and glycidyl azide (GA), and ROCOP of PO and ECH with CO₂. Specifically, this work focused on the ROP of ECH, which exhibited temperature-dependent reactivity. Lower temperatures favored chain propagation and resulted in well-controlled polymerization behavior, while higher temperatures favored chain transfer reactions to the monomer resulting in low molar mass polymers. Catalysts A and B demonstrated comparable reactivities across all polymerizations, indicating that catalyst B, with a higher B/N ratio and spatially arranged ammoniums, may be an ideal candidate. Overall, the general trend of catalytic activity was observed to be A ≅ B > C > D. This study provides valuable insights into the design and synthesis of forthcoming bifunctional N⁺/B catalysts.

中文翻译：

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探索基于硼烷的多铵盐用于环氧化物（共）聚合：深入了解结构-活性关系


基于双官能硼烷的单铵盐的反应性先前已在各种聚合过程中得到证明，包括环氧化物的开环聚合（ROP）以及与CO ₂ 或酸酐的共聚。本研究中，三种双官能硼烷基多铵盐(N ⁺ /B) B、C和D (B ₈ N ₃ (C < b4> )Br ₃ B B ₈ N ₃ (C ₂ )Br ₃ ; ; B ₁₀ N ₄ (C ₂ )Br ₄ ) 以不同的 B/N 比率和两个铵之间的连接长度合成，以及单铵双官能盐、催化剂 A、B ₃ NBr，用作参考。这些主要用作引发剂的催化剂的聚合活性通过环氧丙烷（PO）、环氧氯丙烷（ECH）和缩水甘油叠氮化物（GA）的ROP以及PO和ECH与CO的ROCOP ₂ 进行评价。具体来说，这项工作重点关注 ECH 的 ROP，它表现出温度依赖性反应活性。较低的温度有利于链增长并导致良好控制的聚合行为，而较高的温度有利于单体的链转移反应，从而产生低摩尔质量的聚合物。催化剂 A 和 B 在所有聚合中表现出相当的反应活性，表明具有较高 B/N 比和空间排列的铵的催化剂 B 可能是理想的候选者。总体而言，催化活性的总体趋势为 A ≅ B > C > D。这项研究为即将推出的双功能 N ⁺ /B 催化剂的设计和合成提供了有价值的见解。