POLYMERIZATION OF ACRYLAMIDE PHOTOINITIATED BY CO(NH3)(5)N-3(2-WAVELENGTH VISIBLE-LIGHT IN AQUEOUS-SOLUTION() WITH LONG)

The 546 nm continuous irradiation of acidic aqueous solutions of Co(NH 3)(5)N-3(2+) and acrylamide (AA) results in the formation of polyacryl amide. Excitation of Co(NH3)(5)N-3(2+) yields Co-aq(2+) and N-3(.) rad icals; the latter species initiate the free-radical chain reaction via oxidative electron and/or H atom transfer with the monomer. The posit ive dependence of the rate of polymerization on the square root of the absorbed light intensity and [AA] suggests that the termination step of the chain reaction involves the mutual annihilation of the macrorad icals. ESR spin-trapping experiments demonstrate unequivocally that N- 3(.) radicals are present in the system. Co(NH3)(5)N-3(2+) a suitable photosensitizer for the initiation of free-radical polymerization with visible light.