Pulse and gamma radiolysis studies of 3-sulfo propyl methacrylate in aqueous solutions

Radiation induced polymerization of 3-sulfo propyl methacrylate (SPMA) in a queous solution (10wt%) has been studied by steady state and pulse radiolys is. techniques. The effect of radiation characteristics such as irradiation dose, dose rate and the presence of crosslinking agent on the gel formatio n of SPMA monomer has been investigated. In N-2 saturated solution, the gel formation doses for SPMA were found to be 70 and 258 Gy at dose rates of 1 .2 and 5 kGy h(-1), respectively. The swelling ratio results showed that th e gel obtained at a constant dose of 0.8 kGy dose swells similar to 630 tim es of its dry weight at a dose rate of 5 kGy h(-1) whereas it is 394 times of its dry weight for the dose rate 1.2 kGy h(-1). The reactions of the pri mary radicals of water radiolysis such as e(aq)(-), H-atom, OH radical, O.- , and some oxidizin- radicals like N-3(.) Cl-2(.-), SO4.- and reducing spec ies like CO, with SPMA have been studied using pulse radiolysis technique. The results show that the reaction of e(aq)(-), H-atom and OH radicals with SPMA are in the diffusion controlled limit with their respective bimolecul ar rate constant values being 8.6 x 10(9), 2 x 109 and 1.5 x 10(10) dm(3)mo l(-1) s(-1). The radical anion, SPMA(.-), (lambda (max)= 280 nm) is observe d to undergo fast protonation forming H-adduct, SPMA-H-., (lambda (max) = 3 10 nm) with a pK(a) value of 9.1. Cl-2(,-) reacts with a bimolecular rate c onstant of 3.5 x 10(7) dm(3) mol(-1) s(-1) forming solute radical cation (l ambda (max) = 265 mn). One-electron oxidation and reduction potentials for SPMA/SPMA(,+) and SPMA/SPMA(.-) couples are estimated to be more than + 1.6 and less than - 1.9 V, respectively. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.