Aquivion® PerfluoroSulfonic Acid ionomer membranes: A micro-Raman spectroscopic study of ageing

Recent interest in alternative energy technologies promoted the development of perfluorinated polymer membranes for fuel cells; the degradation mechanism occurring during operation and the polymer ageing that may lead to membrane failure are still a matter of investigation with the aim to identify proper testing protocols and analytical methods. This study illustrates some results obtained through micro Raman spectroscopy; this analytical technique showed itself to be a powerful tool in terms of spatial resolution and chemical data gathering. Detailed analytical and structural information along the cross sections of two membrane grades have been presented, shedding light on intrinsic structural modifications related to overall membrane performance. This study clearly shows an ununiformly distributed loss of sulfonic groups in two different Aquivion® membrane grades, being the spectroscopic technique able to unveil very subtle effects due to equivalent weight and membrane thickness variations. The overall results support the mechanism previously proposed by other authors using different analytical techniques.