Aromatic Xanthates and Dithiocarbamates for the Polymerization of Ethylene through Reversible Addition–Fragmentation Chain Transfer (RAFT) Article Swipe
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· 2019
· Open Access
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· DOI: https://doi.org/10.1002/anie.201905629
· OA: W2963333071
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 n of 1000 g mol −1 . The loss of chain‐ends was minor for dithiocarbamates, yielding polyethylene up to M n =3000 g mol −1 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.
