文献类型：期刊文献

英文题名：Catalyst-Free Dynamic Covalent Knoevenagel/Hydrazide Condensation for Polyacylhydrazones and Covalent Adaptable Networks

作者：Li, Pengyun[1,2];Zhang, Jingwen[1,2];Wang, Zhiqiang[1,2];Li, Chong[1,2];Wu, Huiping[1,2];Lei, Mengying[1,2];Yan, Ge[1,2];Tian, He[1,2];Gu, Ruirui[1,2];Qu, Da-Hui[1,2]

机构：[1]East China Univ Sci & Technol, Inst Fine Chem, Frontiers Sci Ctr Materiobiol & Dynam Chem, Key Lab Adv Mat,Feringa Nobel Prize Scientist Join, 130 Meilong Rd, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China

年份：2025

卷号：64

期号：29

外文期刊名：ANGEWANDTE CHEMIE-INTERNATIONAL EDITION

收录：;EI(收录号：20252118477707);WOS:【SCI-EXPANDED(收录号:WOS:001493781600001)】；

基金：This work was supported by the National Natural Science Foundation of China (grant No. 22025503, 22205064, 22220102004), Science and Technology Commission of Shanghai Municipality (24DX1400200), the Innovation Program of Shanghai Municipal Education Commission (2023ZKZD40), the Programme of Introducing Talents of Discipline to Universities (grant no. B16017), the Shanghai Natural Science Foundation Project (23JC1401700), the Fundamental Research Funds for the Central Universities, the CNPC Innovation Found (2024DQ02-0410), and Shanghai Pujiang Program (grant No. 22PJ1402200).

语种：英文

外文关键词：Covalent adaptable networks; Dynamic covalent chemistry; Dynamic polymers; Knoevenagel/hydrazide condensation; Polyacylhydrazones

摘要：The rapid advancement of dynamic covalent chemistry (DCvC) has significantly impacted both chemistry and materials science. There is an increasing need for exploring catalyst-free dynamic covalent reactions with large equilibrium constant (K-eq) ranges to provide new avenues for the tailored design of dynamic polymers. Here, we report a catalyst-free dynamic covalent condensation reaction between Knoevenagel derivatives (Kn) and hydrazides to generate acylhydrazones. Systematic small-molecule studies validate a significant substituent effect on the Kn reactant, resulting in a wide K-eq range covering nearly four orders of magnitude (0.1-719). The high K-eq values (>500) achieved in polar aprotic solvents enable the catalyst-free synthesis of high-molar-mass (-180 kDa) polyacylhydrazones. The retention of by-products during polycondensation leads to concentration-dependent topology switching between polymeric and macrocyclic acylhydrazones. By leveraging this reaction, we developed a novel covalent adaptable network (CAN) that exhibits remarkable stress relaxation properties (38 s at 160 degrees C), facilitating efficient thermal reprocessing while maintaining high mechanical performance. This condensation reaction enriches the dynamic covalent toolbox and offers a versatile approach for the design and fabrication of dynamic polymers with tailored mechanical and dynamic behavior.