Analysis of proton-conducting organic–inorganic hybrid materials based on sulphonated poly(ether ether ketone) and phosphotungstic acid via ASAXS and WAXS

Abstract

a b s t r a c tIn the present paper the distribution of phosphotungstic acid (PTA, H 3 PW 12 O 40 ) dispersed in sulfonated poly(ether ether ketone), SPEEK, was investigated by Anomalous Small Angle X-ray scattering (ASAXS) and Wide-Angle X-Ray Scattering WAXS techniques. The hydrolysis and condensation of 3-aminopropyltrimethoxysilane or zirconium tetrapropylate in this polymeric matrix were used to produce poly(3-aminopropyl silsesquioxane) or ZrO 2 , as nanofillers. Contrary to previous results reported for membranes containing phosphomolybdic acid, the PTA could be completely dissolved in the SPEEK matrix. The applicability of the Guinier approximation for the SPEEK/PTA membrane confirmed that the PTA was dispersed as isolated nanoparticles. The incorporation of poly(3-aminopropyl silsesquioxane) in the SPEEK/PTA system caused the agglomeration of the heteropolyacid as 30 nm large particles. The ZrO 2 had little effect on the distribution of PTA in the SPEEK matrix. On the other hand, no crystallization of the heteropolyacid was observed in the membranes.

Nanostructure and properties of proton‐conducting sulfonated poly(ether ether ketone) (SPEEK) and zirconia–SPEEK hybrid membranes for direct alcohol fuel cells: effect of the nature of swelling solvent and incorporation of heteropolyacid

“…6) compared with the composite without HPW. Furthermore, as already observed in similar composites,22 HPW is well dissolved in the hybrid matrix, since no peaks associated with crystalline HPW are observed in the XRD patterns.…”

“…This study is justified by the fact that application of such membranes in DAFCs requires the incorporation and good retention of water and that alcohol penetration should be prejudicial to membrane performance. In this sense, the work reported is different from previous nanostructural studies published in the literature that are only concerned with dry zirconia–SPEEK systems where low16 or high22 SDs were employed. Our goal was to understand how the nature of the solvent affects the nanostructural parameters of both polymeric and hybrid membranes and to correlate the nanostructural features with proton conductivity, water retention and barrier properties.…”

“…From a scientific point of view, only few studies aiming to understand how the nanostructural features of zirconia–SPEEK membranes affect the membrane properties have been reported up to now 16, 22. Some authors have shown that pure polymeric Nafion ® or SPEEK membranes exhibit phase‐separated domains consisting of an extremely hydrophobic backbone, which gives morphological stability, and extremely hydrophilic functional groups, which aggregate to form hydrophilic nanodomains (ionic clusters) that should act as water reservoirs 23–29.…”

Recent Development of Polymer Electrolyte Membranes for Fuel Cells

“…The most widely used and intensively studied poly­(arylene ether)-based membrane is SPEEK (Figure a) because its original polymer, poly­(ether ether ketone) (PEEK), is commercially available and has important properties similar to those of many classes of aromatic polymers. − Although the large majority of membranes based on SPEEK does not have the desired lifetime because of the hydroxy radical initiated degradation of SPEEK, there are still some clever routes worthy of being mentioned (Table ) for improving SPEEK membranes. Large improvements in durability have been attained by double cross-linking or the radiation-grafting method, but further improvements are still needed.…”