Photo-initiated polymerization of acrylamide in water

The kinetics of the photo-initiated polymerization of acrylamide in water, at up to 10% w/w polymer and under ambient conditions, are studied using in situ Raman spectroscopy. Three photo-initiators were studied, UO22+, 2,2′-azobis(2-amidinopropane) (“V-50”) and persulfate, with photo-initiation by a low-pressure Hg lamp. The dependences of polymerization rate on time, initiator concentration and initiator type show that classical free-radical polymerization kinetics provides an acceptable quantitative description for this system, even though the rate coefficients controlling aqueous-phase polymerization of acrylamide are very sensitive to changes in solvency during polymerization. The initiation rates with all three photo-initiators were proportional to the absorption at 254 nm wavelength of the Hg lamp.