Alkyl bromide as precursor of initiating dormant species in organocatalyzed living radical polymerization

Alkyl bromide (R-Br) was transformed to alkyl iodide (R-I) in the presence of tributylamine and molecular iodine (I₂). This transformation was conducted in situ in organocatalyzed living radical polymerization; R-Br was used as a starting compound (precursor), and the R-I formed in situ was employed as an initiating dormant species for the polymerization. The polymer molecular weight (M _n being up to 31,000) and its distribution (M _w/M _n = 1.2-1.4) were well controlled up to high conversions (e.g., 80%) in the polymerizations of methyl methacrylate. The monomer scope encompassed functional methacrylates and styrene. Well-defined diblock copolymers were also obtained. R-Br is generally much more stable than R-I upon storage. The use of simple, stable, and inexpensive R-Br as precursors of the dormant species is an attractive feature of this system.