Self-assembled polyelectrolyte multilayered films on Nafion with lowered methanol cross-over for DMFC applications

Abstract

The paper is concerned with the deposition of self-assembled polyelectrolyte multilayer on Naflon membrane by layer-by-layer (LbL) technique with lowered methanol cross-over for direct methanol fuel cell (DMFC) applications. The formation of self-assembled multilayered film on Nafion was characterized by UV-vis spectroscopy and it was found that the polyelectrolyte layers growth on the Nafion surface regularly. Furthermore, the proton conductivity and methanol cross-over measurements were carried out for characterization of the LbL self-assembled composite membranes. The results showed that the concentration and pH of the polyelectrolytes significantly affect the proton conductivity and methanol barrier properties of the composite membranes. 10(-1) monomol polyelectrolyte concentration and pH 1.8 was found to be optimum deposition conditions considering proton conductivity and methanol permeation properties of the LbL self-assembled composite membranes. The methanol permeability of the 10 bilayers of PAH1.8/PSS1.8 deposited LbL self-assembly composite membrane was significantly suppressed and found to be 4.41 X 10(-7) cm(2)/s while the proton conductivity value is in acceptable range for fuel cell applications. (C) 2008 Elsevier B.V. All rights reserved.