(354h) Transport Properties of Highly Sulfonated Poly(styrene-isobutylene-styrene) Membranes With Functionalized Single-Walled Carbon Nanotubes

In this study, single-walled carbon nanotubes (SWCNT) were functionalized with p-aminobenzoic acid, aminomethanesulfonic acid and carboxylic groups to create highly selective polymer nanocomposite membranes. The transport properties of sulfonated poly(styrene-isobutylene-styrene) (SIBS) nanocomposite membranes were measured as function of single-walled carbon nanotube functionalization for gas sensors and fuel cell applications. Elemental analysis (EA) was performed to the sulfonated poly(styrene-isobutylene-styrene) to determine accurate sulfonation levels. Functionalized single-walled carbon nanotubes and nanocomposite membranes were characterized using Fourier transform infrared spectroscopy (FTIR), to confirm the presence of the substituted groups and their interaction with the sulfonated polymer membrane. Thermogravimetrical analysis (TGA) was performed in order to evaluate the thermal stability of the membranes, which increases with sulfonation and shows unique degradations corresponding to each functionalization performed. Water swelling results showed competing effects upon the incorporation of the SWCNT and the functionalized counterparts.  Finally, transport properties, including methanol permeability and proton conductivity, were measured for the nanocomposite membranes. To compare the results, selectivity (i.e., proton conductivity/methanol permeability) of the nanocomposite membranes were determined and compared to Nafion® 117 and other proton exchange membranes.