M. Sarakha et al., POLYMERIZATION OF ACRYLAMIDE PHOTOINITIATED BY CO(NH3)(5)N-3(2-WAVELENGTH VISIBLE-LIGHT IN AQUEOUS-SOLUTION() WITH LONG), Journal of photochemistry and photobiology. A, Chemistry, 91(2), 1995, pp. 165-170
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.