Wolpers Arne, Bergerbit Cédric, Ebeling Bastian, D'Agosto Franck, Monteil Vincent
Université de Lyon, Université Lyon 1, CPE Lyon, CNRS UMR 5265, Laboratoire C2P2, Équipe LCPP, 69616, Villeurbanne, CEDEX, France.
Angew Chem Int Ed Engl. 2019 Oct 1;58(40):14295-14302. doi: 10.1002/anie.201905629. Epub 2019 Aug 23.
Aromatic xanthates and dithiocarbamates were used as chain-transfer agents (CTAs) in reversible addition-fragmentation chain-transfer (RAFT) polymerizations of ethylene under milder conditions (≤80 °C, ≤200 bar). While detrimental side fragmentation of the intermediate radical leading to loss of living chain-ends was observed before with alkyl xanthate CTAs, this was absent for the aromatic CTAs. The loss of living chain-ends was nevertheless detected for the aromatic xanthates via a different mechanism based on cross-termination. Narrow molar-mass distributions with dispersities between 1.2 and 1.3 were still obtained up to number average molar masses M of 1000 g mol . The loss of chain-ends was minor for dithiocarbamates, yielding polyethylene up to M =3000 g mol with dispersities between 1.4 and 1.8. While systems investigated showed significant rate retardation, the dithiocarbamates are the first CTAs giving polyethylene with a high livingness via RAFT polymerization.
在较为温和的条件下（≤80 °C，≤200 bar），芳香族黄原酸酯和二硫代氨基甲酸盐被用作可逆加成-断裂链转移（RAFT）聚合乙烯反应中的链转移剂（CTA）。虽然之前使用烷基黄原酸酯CTA时观察到中间自由基存在有害的链端损失副反应，但芳香族CTA不存在这种情况。不过，通过基于交叉终止的不同机制，仍检测到芳香族黄原酸酯存在链端损失。在数均摩尔质量M达到1000 g mol 之前，仍可获得分散度在1.2至1.3之间的窄摩尔质量分布。二硫代氨基甲酸盐的链端损失较小，可得到数均摩尔质量M =3000 g mol 、分散度在1.4至1.8之间的聚乙烯。虽然所研究的体系显示出显著的速率减缓，但二硫代氨基甲酸盐是首个通过RAFT聚合得到具有高活性聚乙烯的CTA。
