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Photocatalytic Degradation of Poly(Acrylamide-co-acrylic Acid)

Vinu, R and Madras, Giridhar (2008) Photocatalytic Degradation of Poly(Acrylamide-co-acrylic Acid). In: Journal of Physical Chemistry B, 112 (30). pp. 8928-8935.

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Poly(acrylamide-co-acrylic acid) copolymers of different compositions were synthesized and characterized. The copolymers were statistical with a relatively high percentage of acrylamide units, as determined by $^{13}C$ NMR. Reactivity ratios calculated by the Finemann-Ross and Kelen-Tudos methods showed that the copolymers were random with a reactivity ratio of $r_{AM}=3.76$ and $r_{AA}=0.28$ The photolytic and photocatalytic degradation of the copolymers and the homopolymers was conducted in the presence of combustion-synthesized nano anatase titania. The degradation of the copolymer in the presence of combustion-synthesized titania was significantly higher than that observed in the presence of commercial titania, Degussa P-25. The degradation was modeled by using continuous distribution kinetics by following the time evolution of molecular weight distribution. The degradation follows a two step mechanism, wherein the rapid first step comprises the scission of weak acrylic acid units along the chain which is followed by the breakage of relatively strong acrylamide units. The rate constants for the weak and strong links follow a linear trend with the percentage of acrylic acid and acrylamide in the copolymer, respectively. This linear variation can be correlated with a similar trend observed for the activation energies obtained for the pyrolytic degradation of the polymers.

Item Type: Journal Article
Publication: Journal of Physical Chemistry B
Publisher: American Chemical Society
Additional Information: Copyright of this article belongs to American Chemical Society.
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Date Deposited: 06 Oct 2008 09:43
Last Modified: 19 Sep 2010 04:51
URI: http://eprints.iisc.ac.in/id/eprint/16152

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