Electrochemistry Laboratory, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
Phys Chem Chem Phys. 2020 Feb 28;22(8):4516-4525. doi: 10.1039/c9cp05454e. Epub 2020 Feb 12.
Both synthetic polymers (membranes, coatings, packaging) and natural polymers (DNA, proteins) are subject to radical-initiated degradation. In order to mitigate the deterioration of the polymer properties, antioxidant strategies need to be devised. We studied the reactions of poly(α-methylstyrene sulfonate), a model compound for fuel cell membrane materials, with different degrees of polymerization with OH˙ radicals as well as subsequent reactions. We observed the resulting OH˙-adducts to react with oxygen and eliminate HO, the relative likelihood of which is determined by pH and molecular weight. The resulting radical cations can be reduced back to the parent molecule by cerium(iii). This 'repair' reaction is also dependent on molecular weight likely because of intramolecular stabilization. The results from this study provide a starting point for the development of new hydrocarbon-based ionomer materials for fuel cells that are more resistant to radical induced degradation through the detoxification of intermediates via damage transfer and repair pathways. Furthermore, a more fundamental understanding of the mechanisms behind conventional antioxidants in medicine, such as ceria nanoparticles, is achieved.
合成聚合物（膜、涂层、包装）和天然聚合物（DNA、蛋白质）都容易受到自由基引发的降解。为了减轻聚合物性能的恶化，需要设计抗氧化策略。我们研究了聚（α-甲基苯乙烯磺酸盐）（一种燃料电池膜材料的模型化合物）与不同聚合度的 OH˙自由基的反应以及随后的反应。我们观察到生成的 OH˙加合物与氧反应并消除 HO，其相对可能性由 pH 值和分子量决定。生成的自由基阳离子可以通过铈(iii)还原回母体分子。这种“修复”反应也依赖于分子量，可能是由于分子内稳定化。本研究的结果为开发用于燃料电池的新型基于烃的离聚物材料提供了起点，这些材料通过通过损伤转移和修复途径使中间体解毒，从而更能抵抗自由基诱导的降解。此外，对医学中传统抗氧化剂（如氧化铈纳米颗粒）背后的机制有了更基本的了解。
