Cationic quaternary ammonium salt-catalyzed LED-induced living radical polymerization with in situ halogen exchange†
Cationic quaternary ammonium salts were employed as organocatalysts for light-emitting diode (LED)-induced living radical polymerization (LRP) with the in situ halogen exchange of methacrylate monomers. As the most important type of cationic surfactant, they were chosen not only due to their merits of environmental friendliness, affordability, facile operation, high reactivity, but also because of their strong ability to coordinate with iodine. The obtained poly(methyl methacrylate)s presented targeted molecular weight (Mn) values with corresponding high monomer conversions and narrow distributions of Mn with different cationic quaternary ammonium salts under white-LED irradiation. Polymerization was instantly switched “on” and “off” by an intermittent irradiation stimulus sequence, which confirmed the precise temporal control over polymerization. The successful polymerization of functional methacrylates and chain extensions demonstrated that cationic quaternary ammonium salts are efficient organocatalysts for LED-induced LRP.