Inorganic additives heteropolyacids

Overall, AB-PBI and sAB-PBI are possible alternative to Nafion-type membranes, because of the nearly zero dependence of conductivity on water. These membranes also have the requisite mechanical and thermal stability, while achieving moderate levels of proton conductivity that can be further modified with inorganic additives, such as heteropolyacids. 

Thus, the addition of silica and heteropolyacid modifies the relative ratio between crystalline and amorphous structure of ctist Nafion with respect to bare Ntifion. Yet, due to the low loading of silica and heteropolyacid in the membrane (3% silica, less than 1.5% PWA), it appears unlikely that the inorganic components are responsible of such significant modification in the Nafion structure. More probably, the observed changes have to be attributed to the final thermal treatment (160°C). 

To improve proton transport of PFSA membranes at high temperatures and in order to operate PFSA membranes at temperatures above 100°C, inorganic compounds such as Si02 and Ti02 were employed as additives to retain water in the Naflon membranes for an acceptable proton conductivity. Proton conductors such as zirconium phosphate, heteropolyacid/ and heterocycle compounds including imidazole,benzimidazole, triazole, and polyfunctional phosphonic acid were also added in the Naflon membrane. In addition, ionic liquids were applied to fabricate composite Naflon membranes due to their anhydrous high conductivity and good thermal stability. Besides, Naflon/Naflon-functionalized multiwalled carbon nanotube composite membrane exhibits a remarkable improvement in proton conductivity compared to the pristine Naflon membrane. ... 

---