Photocontrolled Organocatalyzed Living Radical Polymerization Feasible over a Wide Range of Wavelengths.

Abstract

Photocontrolled organocatalyzed living radical polymerization was conducted over a wide range of irradiation wavelengths (350-750 nm). The polymerization was induced and controlled at the desired wavelengths by exploiting suitable organic catalysts. This system was finely responsive to the irradiation wavelength; the polymerization was instantly switched on and off, and the polymerization rate was sensitively modulated by altering the irradiation wavelength. The polymer molecular weight and its distribution (M(w)/M(n) = 1.1-1.4) were well controlled for methacrylate monomers up to fairly high conversions in many cases. The monomer scope encompassed various functional methacrylates, and their block copolymers were obtained. The feasibility of such a wide range of wavelengths and the fine response to the wavelength are unprecedented features. As a unique application of the wavelength-responsive nature of this system, we demonstrated "one-pot" selective regulation of living radical polymerization and another type of polymerization (ring opening polymerization), where the regulation was achieved by simply altering the irradiation wavelength. Facile operation and applicability to a wide range of polymer designs are advantages of this polymerization.