Regioselective chain transfer agents are used to synthesize narrowly dispersed heterotelechelic polymers with a 15-fold decrease in catalyst consumption using the pulsed addition ROMP (PA-ROMP) technique. The commercially available Grubbs’ third-generation catalyst (G3) is easily prefunctionalized with chain transfer agents in a short reaction time (30 min). After addition and consumption of a monomer, the excess chain transfer agent in the reaction medium end-functionalizes the polymer chain and regenerates the initiator very quickly (within 10 min) via a ring-opening–ring-closing sequence. This regenerated catalyst then initiates the polymerization of a subsequent batch of monomers, and the process is iterated for 15 times. Excellent control over molecular weight and dispersity from SEC analyses (over 15 pulses) confirmed the high efficacy of the chain transfer agents under this PA-ROMP method. The chain transfer agents are also extremely compatible with the synthesis of high molecular weight polymers (M/C = 150) with minimal catalyst decomposition. ¹H NMR as well as MALDI-ToF mass spectrometry further confirmed the high degree of chain end functionalization of the synthesized polymers.

中文翻译：

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脉冲加成ROMP：通过区域选择性链转移剂催化合成杂螯聚合物

区域选择性链转移剂用于合成窄分散的异质遥爪聚合物，使用脉冲加成 ROMP (PA-ROMP) 技术可将催化剂消耗降低 15 倍。市售的 Grubbs 的第三代催化剂 (G3) 很容易用链转移剂在很短的反应时间 (30 分钟) 内进行预功能化。添加和消耗单体后，反应介质中过量的链转移剂使聚合物链末端官能化，并通过开环 - 闭环序列非常快速（在 10 分钟内）再生引发剂。该再生催化剂随后引发后续一批单体的聚合，该过程重复 15 次。SEC 分析（超过 15 个脉冲）对分子量和分散性的出色控制证实了这种 PA-ROMP 方法下链转移剂的高效性。链转移剂还与合成高分子量聚合物 (M/C = 150) 极为相容，且催化剂分解极少。¹ H NMR以及MALDI-ToF质谱进一步证实了合成聚合物的高度链端官能化。