A new method of producing carbon-centered radicals was discovered through the reaction of an alkyl iodide (R-I) with organic salts to reversibly generate the corresponding alkyl radical (R(•)). Via this new reaction, the organic salts were used as new and highly efficient organic catalysts in living radical polymerization. The catalysts included common and inexpensive compounds such as tetrabutylammonium iodide and methyltributylphosphonium iodide. Notably, the catalysts were highly reactive. They enabled the synthesis of high-molecular-weight polymers (up to Mn = 140,000) and the control of acrylate polymerization, which had been difficult with other organic catalysts. The organic salt catalysts were highly versatile, reacting with methacrylate, acrylate, styrene, acrylonitrile, and functional methacrylate monomers. Well-defined block copolymers were also prepared by using this method. A kinetic study quantitatively confirmed the high reactivity of these catalysts. Attractive features of this system include its low cost, its ease of operation, and its ability to access a wide range of polymer designs.

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.

A novel class of living radical polymerization using amines as organic catalysts was developed. It is based on a new reversible activation mechanism, reversible complexation (RC). The polymer molecular weight and its distribution (M w/M n = 1.1–1.4) were well controlled in the polymerizations of methyl methacrylate (MMA), styrene, acrylonitrile, and some functional methacrylates with a fairly high conversion in hours in many cases. The catalysts include such common amines as triethylamine and tetramethylethylenediamine (TMEDA). Their low cost, good environmental safety, and ease of handling may be attractive for possible applications. Kinetic studies supported the RC mechanism. The activation rate constant for the MMA/TMEDA system was large enough to explain why the system provides low-polydispersity polymers from an early stage of polymerization.