Functionalization of track-etched poly (ethylene terephthalate) membranes as a selective filter for hydrogen purification

This paper reports on the carboxylic and amino group functionalization of track-etched poly(ethylene terephthalate) (PET) membranes with different pore size and pore density. Glycolic acid groups were formed by oxidation of hydroxyethyl end groups while amino groups were introduced by amidation of these carboxylic groups with tetraethylenepentamine. These membranes were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to follow the effect of the oxidation process on the molecular weight of the PET and to access the formation of functional groups. As concluded from NMR and XPS results, the density of carboxyl and amino group increases in comparison to pristine PET membranes. The larger the pore diameter and the pore density, the higher is the extent of functionalization. We demonstrate the deposition of palladium (Pd) nanoparticles onto pore walls and pore surfaces of PET membranes for potential use in hydrogen separation or sensing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (in SEM) results show presence of Pd nanoparticles in functionalized PET membranes pointing to an enhanced binding capability of Pd nanoparticles that can be used for hydrogen extraction from a mixture of gases.