The kinetics of the cross-linking reaction of partially hydrolyzed polyacrylamide (HPAAm) by Cr3+ have been studied over a range of experimental conditions by means of UV spectroscopy. The kinetic rate law, k = A exp(−Ea/RT)[Cr3+][H+]−0.8[P]0.8, is in reasonable agreement with that reported previously for the uptake of Cr3+ by HPAAm for a different range of compositions and agrees closely with that reported for the reaction of Cr3+ with carboxylate monomers. The frequency factor A ((4.9 ± 0.5) × 108 s−1) and activation energy Ea (19 ± 1.8 kcal/mol) were derived for the polymer reaction in experiments conducted between 293 and 353 K. Earlier proposals that the rate determining step on the pathway to polymer crosslinking involves the oligomerization of hydrated Cr3+ ions are excluded by the present results. EPR studies carried out on the Cr3+ solutions and dialyzed gels provide insight into the nature of the cross-linking Cr3+ species produced subsequent to the rate determining step. © 1994, American Chemical Society. All rights reserved.
Montanari, L., Scotti, R., Lockard, T. (1994). Kinetics and mechanism of the reaction of hydrated Cr(III) with partially hydrolized polyacrylamide. MACROMOLECULES, 27(12), 3341-3348 [10.1021/ma00090a031].
Kinetics and mechanism of the reaction of hydrated Cr(III) with partially hydrolized polyacrylamide
SCOTTI, ROBERTO;
1994
Abstract
The kinetics of the cross-linking reaction of partially hydrolyzed polyacrylamide (HPAAm) by Cr3+ have been studied over a range of experimental conditions by means of UV spectroscopy. The kinetic rate law, k = A exp(−Ea/RT)[Cr3+][H+]−0.8[P]0.8, is in reasonable agreement with that reported previously for the uptake of Cr3+ by HPAAm for a different range of compositions and agrees closely with that reported for the reaction of Cr3+ with carboxylate monomers. The frequency factor A ((4.9 ± 0.5) × 108 s−1) and activation energy Ea (19 ± 1.8 kcal/mol) were derived for the polymer reaction in experiments conducted between 293 and 353 K. Earlier proposals that the rate determining step on the pathway to polymer crosslinking involves the oligomerization of hydrated Cr3+ ions are excluded by the present results. EPR studies carried out on the Cr3+ solutions and dialyzed gels provide insight into the nature of the cross-linking Cr3+ species produced subsequent to the rate determining step. © 1994, American Chemical Society. All rights reserved.
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