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    论文
    Structure and activity relationship studies of N-heterocyclic olefin and thiourea/urea catalytic systems: application in ring-opening polymerization of lactones
    第一作者： Zhou, L (Zhou, Li); Wang, ZY (Wang, Zhenyu); Xu, GQ (Xu, Guangqiang); Lv, CD (Lv, Chengdong); Wang, QG (Wang, Qinggang);
    联系作者： Zhou, L (Zhou, Li); Wang, ZY (Wang, Zhenyu); Xu, GQ (Xu, Guangqiang); Lv, CD (Lv, Chengdong); Wang, QG (Wang, Qinggang);
    发表年度： 2021
    期： 12
    卷： 12
    页： 1806-1815
    摘要： A highly efficient and controllable ring-opening polymerization of lactones (delta-valerolactone, epsilon-caprolactone and rac-lactide) has been achieved by using N-heterocyclic olefin (NHO) and thiourea/urea (TU/U) catalytic systems. This catalytic system showed high ring-opening activity and stereoselectivity, delivering biodegradable polyesters with high chain-end fidelity, controlled molecular weights and narrow molar mass dispersities. A detailed investigation of the structure-activity relationship was performed by exploring five NHOs and fourteen TUs/Us. For a fixed NHO, when the acidity of TUs/Us decreases, the polymerization mechanism changes from the (thio)urea anion to the neutral cooperative activation mode, and the catalytic activity first increases and then decreases, displaying a highly effective interval. For a given TU or U, as the basicity of NHOs increases, the catalytic performance improves correspondingly. Besides, highly isoselective ROP of rac-LA (P-m = 0.93) at -78 degrees C has been also achieved, highlighting the versatility of the NHO/TU(U) system. These findings enrich the type of TU/U and base organocatalyst.
    刊物名称： POLYMER CHEMISTRY
    影响因子： 4.76
    全文链接： http://pubs.rsc.org/en/content/articlelanding/2021/PY/D0PY01747G