Phosphonic acid-containing blends and phosphonic acid-containing polymers

Abstract

The invention relates to blends and blend membranes from low-molecular hydroxymethylene-oligo-phosphonic acids R—C(PO3H2)x(OH)y and polymers, the group R representing any organic group and the polymers containing the following functional groups: cation exchanger groups or their nonionic precursors of the type SO2X, X═HaI, OH, OMe, NR1R2, OR1 with Me=any metal cation or ammonium cation, R1, R2=H or any aryl- or alkyl group, POX2, COX and / or basic groups such as primary, secondary or tertiary amino groups, imidazole groups, pyridine groups, pyrazole groups etc. and / or OH groups. Low molecular hydroxymethylene-oligo-phosphonic acids R—C(PO3H2)x(OH)y are preferred in which x=2 and y=1. The invention also relates to low-molecular hydroxymethylene-oligo-phosphonic acids R—C(PO3H2)2(OH)1 and polymers, wherein the group R of the hydroxymethylene-oligophosphonic acid contains an aliphatic or aromatic basic group which ionically interacts with the acidic groups of the polymer or of the polymer mixture. The invention further relates to blends and blend membranes from low-molecular hydroxymethylene-oligo-phosphonic acids R—C(PO3H2)2(OH)1 and polymers, wherein the OH groups of the low-molecular hydroxymethylene-1,1-bisphosphonic acid are covalently cross-linked with each other or optionally with OH groups of the polymer. The invention also relates to polymers that are modified with the 1-hydroxymethylene-1,1-bisphosphonic acid group. The polymers are produced by reacting polymers which contain carboxylic acid groups or carboxylic halide groups —COHaI (Hal═F, Cl, Br, I) with phosphite compounds or by reacting polymeric aldehydes or polymeric keto compounds with phosphite esters while carrying out an amine catalysis, an oxidation of the intermediary hydroxyphosphonic acid with MnO2 or any other oxidant. The invention finally relates to methods for producing the aforementioned materials and to the use of membranes of the aforementioned materials in membrane processes and especially in fuel cells, even at temperatures of >100° C.

Description

BACKGROUND OF THE INVENTION[0001]Commercially available ionomer membranes based on perfluorinated sulfonic acids can be used at temperatures below 100° C. in electrochemical cells, especially in fuel cells and show in this temperature range good H+-conductivities and high (electro)chemical stability. They can't be used at temperatures above 100° C., because they dry out and fort his reason their proton conductivity decreases several orders of magnitude.1,2 However it makes sense to run a fuel cell at temperatures above 100° C. because the CO-tolerance of the fuel cell reaction in this temperature range is markedly greater due to a faster electrode kinetic as below 100° C.3. However as explained above is the use of sulfonated ionomer membranes at temperatures above 100° C. in fuel cells atmospheric pressure and with out humidifying of the membrane not possible. In the literature several approches for alternative proton conductors in the temperature range of approximately 100 to 200° ...

AI Technical Summary

Benefits of technology

The invention relates to using blends of polymers and low molecular 1-hydroxymethylene-1,1-bisphosphonic acids in membrane applications. The technical effect of this invention is the prevention of bleeding out of the polymer blends.

Problems solved by technology

However as explained above is the use of sulfonated ionomer membranes at temperatures above 100° C. in fuel cells atmospheric pressure and with out humidifying of the membrane not possible.

Kerres, F. Schönberger, unveröffentlichte Ergebnissephosphonic acids tend at temperatures around 120° C. to condensate, which renders their use in fuel cells in the temperature range above >100° C. so far impossible.

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