Time-Resolved EPR as a Tool to Investigate Oxygen Quenching in Photoinitiated Radical Polymerizations

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• 作者：Daniela Hristova-Neeley ; Dmytro Neshchadin ; Georg Gescheidt
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：October 29, 2015
• 年：2015
• 卷：119
• 期：43
• 页码：13883-13887
• 全文大小：294K
• ISSN：1520-5207

文摘

It is challenging to obtain absolute rate constants for the quenching of organic radicals by molecular oxygen because they often do not present absorbance in the UV鈥搗is range. Here, it is shown that time-resolved EPR (chemically induced dynamic electron polarization, or CIDEP) spectroscopy is useful in establishing rate constants for the addition of benzoyl radicals to molecular oxygen. It was found that benzoyl radicals are particularly reactive toward O₂ and can, therefore, act as oxygen scavengers in the initiating phase of radical polymerizations. Kinetic simulations underpin this reactivity.