Layer-by-layer self-assembly of polyaniline on sulfonated poly(arylene ether ketone) membrane with high proton conductivity and low methanol crossover

摘要

Sulfonated poly(arylene ether ketone) bearing carboxyl groups (SPAEK-C) membranes were first modified by alternating deposition of oppositely charged polyaniline (PANI) and phosphotungstic acid (PWA) via the layer-by-layer method in order to prevent the cross-over of methanol in a direct methanol fuel cell. The methanol permeability of SPAEK-C-(PANI/PWA)_5 is 2 orders of magnitude less than those of Nafion 117 and pristine SPAEK-C. Furthermore, the modified membrane shows a proton conductivity of 0.093 Scm~(-1) at 25 ℃ and 0.24 Scm~(-1) at 80℃, which are superior to those of Nafion 117 and pristine SPAEK-C. Fourier transform infrared spectroscopy confirms that PANI and PWA are assembled in the multilayers. The SEM images show the presence of thin PANI/PWA layers coated on the SPAEK-C membrane. Thermal stability, water uptake, water swelling, proton and electron conductivity at different temperature of the SPAEK-C and SPAEK-C-(PANI/PWA)_n membranes are also investigated.