The development and applications of an organocatalyzed living radical polymerization via halogen-bonding catalysis, i.e., reversible complexation mediated polymerization (RCMP), are highlighted.
The molecular weight distribution of polymer, termed dispersity (Đ), is a fundamental parameter that determines polymer properties. Sodium azide (NaN 3 ) functions as a catalyst in organocatalyzed living radical polymerization when the reaction medium is nonpolar. In contrast, NaN 3 can act as a nucleophile when the reaction medium is polar. In this paper, we report an efficient approach to dispersity control by exploiting the dual functions of NaN 3 under the varied solvent polarity. Simultaneous polymerization and chainend substitution allowed us to tune the Đ values of various polymethacrylates and poly(butyl acrylate). Notably, the Đ value could be tuned to a wide range approximately from 1.2 to 2.0 for polymethacrylates and to 3.8 for poly(butyl acrylate). This approach afforded polymer brushes on surfaces with tailored Đ values. An interesting finding was that the polymer brushes exhibited a unique interaction with external molecules, depending on the Đ value.
An effective method to synthesize azido‐end polymethacrylates from tetrabutylammonium azide (BNN3) in a nonpolar solvent (toluene) was developed. Several low‐mass alkyl halides were reacted with BNN3 in toluene as model reactions and the rate constants of these reactions were determined, to confirm fast BNN3 azidation for tertiary and secondary halides. The end‐group transformation of halide‐end polymethacrylates was effective and nearly quantitative. Notably, the combination of organocatalyzed living (or reversible deactivation) radical polymerization and BNN3 azidation enabled the metal‐free synthesis of azido‐end polymethacrylates, including single‐azido‐end and multi‐azido‐end functional homopolymers and block copolymers. The rapid and quantitative reaction without the requirement for a large excess of BNN3, metal‐free and polar‐solvent‐free nature, and broad polymer scope are attractive features of this azidation.
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