Separation method and device with semipermeable membranes comprising sulfonated polyimides

Membranes with improved permselectivity in electrolytic and electrodialysis cells in acidic media are based on sulfonated polyimides prepd. from two diamines, 1 of which has sulfo groups. A typical membrane was based on a polyimide with repeating units having structures based on 2,2'-disulfo-4,4'-biphenyldiamine, 4,4'-diaminodiphenyl ether, and 1,4,5,8-naphthalenetetracarboxylic aci

Fabrication of electrode-membrane assemblies containing heat-stable polymers for fuel cells

Electrode-membrane-electrode (EME) assemblies for fuel cells are prepd. by (1) pouring a heat-stable polymer onto a support to obtain a heat-stable polymer soln. film, (2) partly drying the polymer film by evapg. the solvent from the soln., (3) depositing an electrode on the surface of the polymer film during the drying process before it is completely dry, (4) completely drying the assembly, (5) sepg. the assembly of the membrane and the electrode from the substrate. In step (3), the active surface of the electrode faces the surface of the polymer film. The heat-stable polymers are selected from sulfonated polyimides, polyether-polysulfones, polystyrene, polyether-polyketones, polybenzoxazoles, polybenzimidazoles, and poly-p-phenylene

sulfonated copolyimides: influence of structural parameters on gas separation properties

International audienc

Water vapour transport mechanism in naphthalenic sulfonated polyimides

International audienc

Fabrication of electrode-membrane assemblies containing heat-stable polymers for fuel cells

Electrode-membrane-electrode (EME) assemblies for fuel cells are prepd. by (1) pouring a heat-stable polymer onto a support to obtain a heat-stable polymer soln. film, (2) partly drying the polymer film by evapg. the solvent from the soln., (3) depositing an electrode on the surface of the polymer film during the drying process before it is completely dry, (4) completely drying the assembly, (5) sepg. the assembly of the membrane and the electrode from the substrate. In step (3), the active surface of the electrode faces the surface of the polymer film. The heat-stable polymers are selected from sulfonated polyimides, polyether-polysulfones, polystyrene, polyether-polyketones, polybenzoxazoles, polybenzimidazoles, and poly-p-phenylene

Kinetics of water vapor sorption in sulfonated polyimide membranes

International audienc

Distribution of the « micelles » in hydrated perfluorinated ionomer membranes from SANS experiments

The analysis of the shape and intensity of small angle neutron scattering (SANS) curves obtained on a perfluorinated ionomer membrane with different water contents suggests a model for the distribution of the hydrated « micelles » in the perfluorinated matrix. The model describes a locally ordered structure for these micelles with four first neighbours located at a well defined distance embedded in a completely disordered gas of micelles. Only two adjustable parameters are necessary to fit the experimental scattering curves over the whole q range, based on the radial distribution function associated with this locally « diamond-like » (tetrahedral) structure. It is demonstrated that both the zero angle upturn and the ionomer peak are linked with the ionic domain existence. It is shown that there is no need for long range fluctuations or large scale defects to interpret the zero angle domain. Our model is in reasonably good agreement with all the experimental results for q (q = 4 π sin θ/λ) ranging from 0.02 to 0.26 Å-1 and for water contents from 6 to 26 % (volume fraction).L'analyse de la forme et de l'intensité de spectres de diffusion de neutrons aux petits angles d'une membrane ionomère perfluorosulfonée en équilibre avec différents taux d'humidité nous permet de proposer un modèle pour la distribution des « micelles » hydratées au sein de la matrice perfluorée. Le modèle décrit une structure localement ordonnée de ces micelles avec quatre premiers voisins localisés à une distance bien définie dans un gaz complètement désordonné de micelles. L'ajustement des spectres expérimentaux à partir de la fonction de distribution radiale, déduite de cette structure localement tétraédrique, nécessite seulement deux paramètres ajustables. Nous démontrons que la remontée aux petits angles et le pic ionomère sont liés à l'existence des domaines ioniques. Nous montrons qu'il n'est pas nécessaire d'invoquer l'existence de fluctuations aux grandes distances ou des défauts à grande échelle pour interpréter le domaine des petites valeurs de q. Notre modèle permet l'obtention d'un bon ajustement entre spectres expérimentaux et courbes théoriques pour des valeurs de q (q = 4 π sin θ /λ) comprises entre 0,02 et 0,26 Å-1 et des fractions volumiques en eau de 6 à 26 %

water vapor sorption in naphthalenic sulfonated polyimide membranes

International audienc

Gas transport properties of sulfonated copolyimides: influence of structural parameters and relative humidity

International audienc