A procedure for the production of N-heterocyclic carbene boryl radicals (NHC-BH2 center dot) upon visible light irradiation under soft conditions is presented. New acridine orange (dye)/diphenyl disulfide/NHC-BH3 and dye/sulfonium salt/NHC-BH3 three-component initiating systems are introduced for the efficient visible light photopolymerization of trimethylolpropane triacrylate. The new systems could be extendend to polymerization reactions in water (hydroxyethyl acrylate and hydroxyethyl methyl acrylate), which proceeded with strongly improved polydispersity. The chemical mechanisms are investigated through EPR and photolysis experiments.