Sulfonated poly(phenylene ether ether sulfone) membrane tailored with layer-by-layer self-assembly of poly(diallyldimethylammonium chloride) and phosphotungstic acid for DMFC applications

Poly(diallyldimethylammonium chloride) (PDDA) and phosphotungstic acid (PTA) were used as cationic and anionic polyelectrolyte layers, respectively, in an alternating fashion to enhance the methanol barrier property and oxidative stability of sulfonated poly (phenylene ether ether sulfone) (SPEES) proton exchange membranes (PEMs). The multilayer PEMs were characterized by AFM, FTIR, and AC impedance spectroscopy. Methanol permeability of the multilayered membranes was found to be much lower than the bare SPEES membrane. The multilayered membranes displayed significantly improved oxidative stability and dimensional stability compared to pristine SPEES membrane. Conversely, the water uptake (%) and proton conductivity (S cm(-1)) of the prepared membranes decrease to some extent with increasing the PDDA/PTA bilayers in comparison to the pristine SPEES membrane. The maximum relative selectivity (2.23 x 10(4) S cm(-3) s) and retained weight (88.9%) were observed for SPEES-[PDDA/PTA](5) multilayered membrane. The obtained results exposed the possibility of SPEES-[PDDA/PTA](5) multilayered membrane to serve as high-performance PEMs in direct methanol fuel cells. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47344.