Synthesis and characterization of novel sulfonated polyimide with varying chemical structure for fuel cell applications

Sodium 2-(2, 3-bis (4-aminophenyl) propyl) benzenesulphonate (APBS), a novel sulfonated diamine (NSDA) was synthesized and characterized by 13C NMR. NSDA along with 4,4′-oxydianiline (ODA) and 4,4′-oxydiphthalic anhydride (OPDA) were used for the synthesis of novel sulfonated polyimide (NSPI) thin film through the random copolymerization process via two-step classical method: (1) synthesis of sulfonated poly(amic acid) (SPAA), the precursor; (2) thermal imidization of SPAA film. Novel sulfonated polyimide (NSPI) with a pendant sulfonic acid group was fabricated by the use of this novel NSDA. The imidization of novel NSPI membrane was confirmed by FTIR spectroscopy. Thermal stability, water uptake, ion exchange capacity, hydrolytic and oxidative stabilities were also studied. Relatively high proton conductivity even at 110 °C, makes this SPI membrane suitable to be used as a polymer electrolyte membrane for fuel cell.