Adhesion Improvement of Perfluoro-sulfonic Acid Membrane by UV-irradiation for PEFC Performance

Surface Chemoselective Phototransformation of C–H Bonds on Organic Polymeric Materials and Related High-Tech Applications

“…The resulting reactive oxygen species, termed ROS, are strong oxidizing reagents and include atomic oxygen singlet, molecular oxygen singlet, atomic oxygen triplet, molecular oxygen triplet, hydroxyl radicals, hydrogen peroxide, superoxide, and ozone. These ROS can undergo complex reaction pathways leading to activation of surface C–H bonds, for example, the insertion of a singlet oxygen atom to form ether linkages or hydrogen abstraction by ozone or radical species followed either by cross-linking or by reaction with oxygen species to form oxygen-containing functionalities. ,− Therefore, similar to direct photoscission by VUV photons as described in section 3.1, the photooxidation process is also typically rather complex, involving a combination of multiple reaction pathways from different reactants. The resulting complex microscopic processes, on the one hand, lead to the simultaneous grafting of different oxygen-containing functional groups such as hydroxyl, ether, ketone, carboxylic acid, ester, or lactone structures but, on the other hand, also easily induce physical changes on the irradiated surface such as cross-linking and etching as well as the formation of a loosely bound surface layer of low molecular weight scission products.…”