Plasma polymerized barrier films on membranes for direct methanol fuel cells

The methanol permeation through fuel cell relevant Nafion (R) membranes is investigated at different concentrations of methanol in aqueous solutions. Thin plasma polymerized barrier films are deposited on Nafion (R) membranes in a low pressure microwave generated plasma to reduce their methanol perm eability. The methanol permeability was measured as a function of time usin g a gas chromatograph with a flame ionisation detector. It is shown that a plasma polymer layer with a thickness of approximately 0.27 mum on Nafion ( R) membranes reduces the permeability to methanol by a factor of approximat ely 20. (C) 2001 Elsevier Science B.V. All rights reserved.