Fuel cell membranes prepared from multi-walled carbon nanotubes and silica nanotubes-filled sulfonated polyamide/sulfonated polystyrene porous blend films

A sulfonated polyamide (PA-S) was first synthesized through polycondensation of sulfonated 4,4'-oxydianiline and terephthaloyl chloride. The sulfonation of polystyrene (PS-S) was conducted using a mild sulfonating reagent (98% H2SO4). Two categories of mechanically robust and thermally stable nanocomposites, based on multi-walled carbon nanotube (MWCNT) and silica nanotube (SiNT), i.e. PS-S/PAS/ MWCNT and PS-S/PA-S/SiNT, were prepared by solution blending. Scanning electron micrographs showed good dispersion of filler and adhesion of matrix on the surface of nanotube. Accordingly, a symmetric membrane structure with dense porous top layer, porous sublayer, and fully developed micropores at the bottom were observed. The porous membrane structure was accountable for the excellent water retention capability, and so, higher proton conductivity of new hybrids. Increasing the amount of nanotube from 0.5 to 2 wt.% increased the ultimate tensile stress of functional PS-S/PA-S/MWCNT nanocomposites