Grubbs 3rd-generation (G3) pre-catalyst-initiated ring-opening metathesis polymerization (ROMP) remains an indispensable tool in the polymer chemist's toolbox. Tricyclononenes (TCN) and tricyclononadienes (TCND) represent under-explored classes of monomers for ROMP that have the potential to both advance fundamental knowledge (e.g., structure-polymerization kinetics relationships) and serve as practical tools for the polymer chemist (e.g., post-polymerization functionalization). In this work, a library of TCN and TCND imides, monoesters, and diesters, along with their exo-norbornene counterparts, were synthesized to compare their behaviors in G3-initiated ROMP. Real-time ¹H NMR was used to study their polymerization kinetics; propagation rates (k_p) were extracted for each monomer. To understand the relationships between monomer structure and ROMP propagation rates, density functional theory methods were used to calculate a variety of electronic and steric parameters for each monomer. While electronic parameters (e.g., HOMO energy levels) correlated positively with the measured k_p values, steric parameters generally gave improved correlations, which indicates that monomer size and shape are better predictors for k_p than electronic parameters for this data set. Furthermore, the TCND diester—which contains an electron-deficient cyclobutene that is resistant to ROMP—and its polymer p(TCND) are shown to be highly reactive toward DBU-catalyzed conjugate addition reactions with thiols, providing a protecting- and activating-group free strategy for post-polymerization modification.

中文翻译：

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三环壬烯和三环壬二烯作为受控 ROMP 的有效单体：了解结构-增长速率关系并实现轻松的聚合后改性


格拉布斯第三代 (G3) 催化剂前引发的开环复分解聚合 (ROMP) 仍然是高分子化学家工具箱中不可或缺的工具。三环壬烯 (TCN) 和三环壬二烯 (TCND) 代表了尚未开发的 ROMP 单体类别，它们有潜力推进基础知识（例如结构-聚合动力学关系）并作为高分子化学家的实用工具（例如后聚合）。聚合功能化）。在这项工作中，合成了 TCN 和 TCND 酰亚胺、单酯和二酯及其外型降冰片烯对应物的库，以比较它们在 G3 启动的 ROMP 中的行为。利用实时 ¹ H NMR研究了它们的聚合动力学；提取每个单体的增殖速率（k _p ）。为了了解单体结构和 ROMP 传播速率之间的关系，使用密度泛函理论方法来计算每个单体的各种电子和空间参数。虽然电子参数（例如 HOMO 能级）与测量的 k _p 值呈正相关，但空间参数通常会提供更好的相关性，这表明单体尺寸和形状是 k _p 比该数据集的电子参数。此外，TCND 二酯（含有耐 ROMP 的缺电子环丁烯）及其聚合物 p(TCND) 对 DBU 催化的与硫醇的共轭加成反应具有高度反应性，提供保护基团和活化基团聚合后改性的自由策略。