A facile and clean strategy for synthesizing unimodal polymethacrylates with narrow dispersity (Đ < 1.10) is successfully developed by a near-infrared (NIR) light-emitting diode (LED) light (λmax = 740 nm)-controlled in situ bromine-iodine transformation reversible-deactivation radical polymerization system without the use of NIR dyes and expensive catalysts. In this system, alkyl iodide ethyl α-iodophenylacetate (EIPA) initiator is generated in situ by the nucleophilic substitution reaction between an alkyl bromide compound ethyl α-bromophenylacetate and sodium iodide (NaI). At the same time, excessive NaI is also acted as a highly active catalyst by forming halogen bonds with terminal iodine of the polymer chains in this system to make it capable of precisely synthesizing polymethacrylates with narrow dispersities (Đ = 1.03-1.10). In addition, the strong penetration ability of NIR LED light is illustrated by the successful polymerization even through 11 pieces of A4 paper.
Keywords: NIR LED light; bromine-iodine transformation (BIT); narrow dispersity; polymethacrylates; reversible-deactivation radical polymerization (RDRP).
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