Reversible Chain Transfer Catalyzed Polymerization with Alkyl Iodides Generated from Alkyl Bromides by in Situ Halogen Exchange
Reversible chain transfer catalyzed polymerization (RTCP) is a practical and efficient process for the precise synthesis of polymers with special architecture by using simple phenols (2,4,6-trimethylphenol, TMP) or hydrocarbons (xanthene, XT) as efficient organocatalysts. Herein, alkyl iodide (R-I), which was generated from in situ bromine-iodine transformation of alkyl bromide (R-Br) with sodium iodide (NaI), was served as initiator to mediate RTCP with TMP or XT. MMA and other functional methacrylates, including GMA, DEAM, DMAEMA and BzMA, were successfully initiated by combining organocatalysts and azo initiators to yield polymers with low-polydispersity ( M w / M n =1.1–1.5) and ideal monomer conversions (50%–90%) at moderate temperature. Moreover, 3-armstar polymers were also obtained by this method. The high chain-end fidelity of the obtained poly(methyl methacrylate) with iodine as chain-end group (PMMA-I) was confirmed by chain-extension reaction. The environmentally friendly initiators and organocatalysts exhibit powerful polymerization properties toward RTCP, providing a significant method to synthesize functional polymers.
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