Improvement of the barrier properties of Nafion® by fluoro-modified montmorillonite

in Solid State Ionics (2006), 177(13-14), 1137-1144

Montmorillonite (MMT) was modified by two types of cationic fluorosurfactants in order to improve compatibility with and dispersion within Nafion® membranes. Perfluoropolyether-containing cationic ... [more ▼]

Montmorillonite (MMT) was modified by two types of cationic fluorosurfactants in order to improve compatibility with and dispersion within Nafion® membranes. Perfluoropolyether-containing cationic surfactant improved efficiency, by improving the barrier properties of Nafion® towards methanol. Moreover, the fluoro-modified MMT had no deleterious impact on the ionic conductivity of the membranes in contrast to conventional organo-modified MMT. The performances of a small size fuel cell were accordingly improved. [less ▲]

Impact of acid containing montmorillonite on the properties of Nafion® membranes

in Polymer (2005), 46(25), 11389-11395

The counter-ions of montmorillonite have been exchanged for ammonium cations containing either a sulfonic acid or a carboxylic acid in order to improve the performances of sulfonated membranes in direct ... [more ▼]

The counter-ions of montmorillonite have been exchanged for ammonium cations containing either a sulfonic acid or a carboxylic acid in order to improve the performances of sulfonated membranes in direct methanol fuel cell. These layered silicates have been dispersed within Nafion® by solution mixing. Comparison with conventional organo-modified montmorillonite (Cloisite 30B) shows that the incorporation of carboxylic acid in the clay galleries improves the filler dispersion and, consequently, the methanol barrier properties. Moreover, the negative impact of Cloisite 30B on the ionic conductivity is restricted. [less ▲]

Nafion-layered silicate nanocomposite membrane for fuel cell application

in e-Polymers (2004), (18), 1-13

Direct methanol fuel cells (DMFCs) using a proton exchange membrane as electrolyte is an attractive option for electricity generation. The most widely used membrane in the DMFC system is based on a ... [more ▼]

Direct methanol fuel cells (DMFCs) using a proton exchange membrane as electrolyte is an attractive option for electricity generation. The most widely used membrane in the DMFC system is based on a perfluorinated polymer bearing sulfonic acid functions like Nafion®. The latter combines chemical, mechanical and thermal stability and high protonic conductivity but shows elevated methanol permeability. We propose the preparation of a novel type of hybrid membranes to tentatively solve this problem. This innovative material results from the homogeneous dispersion of a nano-scaled inorganic filler within Nafion. The filler consists of stacks of negatively charged alumino-silicate layers (Cloisite), with a positive counter-ion in the interlamellar space. The purpose of the addition of this filler is to decrease methanol diffusion through the polymer membrane without decreasing too much the ionic conductivity. [less ▲]