Profluorescent nitroxides: Sensors and stabilizers of radical-mediated oxidative damage

Title
Profluorescent nitroxides: Sensors and stabilizers of radical-mediated oxidative damage
Publication Date
2008
Author(s)
Blinco, James P
Keddie, Daniel
Wade, Tim
Barker, Philip J
George, Graeme A
Bottle, Steven E
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Elsevier Ltd
Place of publication
United Kingdom
DOI
10.1016/j.polymdegradstab.2008.05.028
UNE publication id
une:13214
Abstract
In this study, three profluorescent nitroxides 1,1,3,3-tetramethyldibenzo[e,g]isoindolin-2-yloxyl (TMDBIO), 1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalene-2-yloxyl (TMAO) and 5-[2-(4-methoxycarbonyl-phenyl)-ethenyl]1,1,3,3-tetramethylisoindoline-2-yloxyl (MeCSTMIO) were tested as probes for radical-mediated damage in polypropylene arising from both UV and thermally initiated sources. These nitroxides possess a very low fluorescence quantum yield due to quenching by the nitroxide group; however, when the free-radical moiety is removed by reaction with alkyl radicals (to give an alkoxyamine), strong fluorescence is observed. The results obtained from this profluorescent nitroxide trapping technique compare favourably with other methods of monitoring degradation, provided the appropriate probe is chosen for the conditions of oxidation, signalling an indication of damage well before other techniques show any response. The technique was also applied to the monitoring of crosslinked polyester coating resins. Differentiation in the oxidative stability of the resins was evident after as little as 200 min where other monitoring techniques require up to 300 h of accelerated degradation. This highlights the sensitivity of this method as well as demonstrating the scope of this technique to assess polymer stability.
Link
Citation
Polymer Degradation and Stability, 93(9), p. 1613-1618
ISSN
1873-2321
0141-3910
Start page
1613
End page
1618

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