NOVEL PHOSPHONATED FLUOROELASTOMERS (PFKMS), PHOSPHONATED PERFLUOROELASTOMERS (PFFKMS), THEIR PROCESS OF PREPARATION AND USE IN ELECTROMEMBRANE APPLICATIONS

Abstract

The disclosure relates to a class of high and low phosphonated aliphatic fluoropolymer rubbers (pFKM) and perfluoropolymer rubbers (pFFKM) based on FKM and FFKM as well as the process for their preparation and their applications.

Claims

1.-18. (canceled)

19. A phosphonated polymer, comprising: an aliphatic polymer backbone; and a phosphonic acid group, wherein the phosphonated polymer is selected from the group consisting of phosphonated aliphatic fluoropolymer rubbers (pFKM) synthesized from fluoropolymer rubber (FKM) and phosphonated aliphatic perfluoropolymer rubbers (pFFKM) synthesized from perfluoropolymer rubber (FFKM), wherein the phosphonic acid group is present directly on the backbone or on a side chain of the phosphonated polymer.

20. The phosphonated polymer according to claim 19, wherein the backbone of the phosphonated polymer comprises two or more monomers selected from the group consisting of vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), perfluoroalkylvinylether (PAVE), propylene, and ethylene, and wherein the phosphonated polymer can be shaped into a membrane.

21. The phosphonated polymer according to claim 19, wherein unreacted reactive groups (X) without phosphonic acid group are present, wherein the unreacted reactive groups (X) can be covalently crosslinked to produce covalently crosslinked membranes, and wherein the unreacted reactive groups (X) are selected from the group consisting of I, Br, Cl, HCN, N3, OCN, NCO, CNO, SCN, NCS, SeCN, and free OH of a bisphenol AF side chain.

22. A membrane, comprising: the phosphonated polymer according to claim 19, blended with a basic polymer selected from the group consisting of polybenzimidazole and anion exchange polymers, the membrane being an acid-base blend membrane, a covalently crosslinked membrane, or a covalently crosslinked acid-base blend membrane.

23. The membrane according to claim 22, wherein a mixing ratio between the phosphonated polymer and the basic polymer is between 99 mol % phosphonated polymer and 1 mol % basic polymer to 1 mol % phosphonated polymer and 99 mol % basic polymer.

24. The membrane according to claim 22, further comprising a sulfonated polymer.

25. A method, comprising: doping the membrane as in claim 22 with phosphoric acid.

26. A method, comprising: doping the membrane as in claim 22 with phosphoric acid, a doping level of the phosphoric acid being between 40 wt. % and 500 wt. %.

27. A method for preparing a phosphonated polymer, comprising: dissolving or suspending FKM or FFKM in a phosphonating agent; heating the dissolved or suspended FKM or FFKM to temperatures between 40? C. to 200? C. for 30 minutes to 12 hours; thereafter distilling off or otherwise removing excess phosphonating agent; and isolating the phosphonated polymer by dialysis or precipitation, wherein the FKM or FFKM has at least one reactive group (X), wherein the least one reactive group (X) is at least one member selected from the group consisting of I, Br, Cl, H, CN, N3, OCN, NCO, CNO, SCN, NCS, SeCN, and free OH of a bisphenol AF side chain.

28. The method according to claim 27, wherein dissolving or suspending FKM or FFKM in a phosphonating agent comprises adding at least one further solvent.

29. The method according to claim 28, wherein the further solvent is at least one member selected from the group consisting of N-methylpyrolidone (NMP), Dimethylecetamide (DMAc), and Dimethylsulfoxide (DMSO).

30. The method according to claim 27, wherein the phosphonating agent is tris(trimethylsilyl)phosphite.

31. An electrochemical cell comprising the phosphonated polymer according to claim 19.

32. A low or medium temperature polymer electrolyte fuel cells PEM fuel cells in a temperature range from ?30? C. to 250? C. comprising the phosphonated polymer according to claim 19.

33. A low- or medium temperature PEM electrolysers in a temperature range from 0? C. to 250? C. comprising the phosphonated polymer according to claim 19.

34. A chemical synthesis reactor from ?70? C. to 250? C. comprising the phosphonated polymer according to claim 19.

35. A separator in a primary battery or a secondary battery comprising the phosphonated polymer according to claim 19.

36. A binder in an electrodes of a primary battery or a secondary battery comprising the phosphonated polymer according to claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1: Example of the basic structure for an FFKM with reactive group X

[0029] FIG. 2: Conductivities of the phosphonated polymers (top) and for comparison (bottom) of a Nafion 212 measured at 50% RH at 30? C. decreasing to 0.2% RH at 180? C.

[0030] FIG. 3: Polarization curve of a membrane made of the phosphonated polymer with IEC.sub.total=2.62 mmol/g, showing that phosphonation has taken place and that the application in electrochemical cells works.

[0031] FIG. 4: Exemplary reaction scheme of the phosphonation reaction.

DETAILED DESCRIPTION

Non-Limiting Embodiment Example

[0032] 10 g of an FKM is mixed with 90 g of N-methylpyrolidone (NMP), stirred, heated and dissolved. 50 g of TTMSP is added to the solution and heated to 160? C. After a few minutes, gas starts to evolve, which first accelerates and then slowly comes to a standstill, indicating the end of the reaction. The solution is kept at reaction temperature for another 2 to 12 hours to make sure that the reaction is complete.

[0033] Now the byproducts and excess TTMSP can be removed by distillation. The pFKM dissolved in the NMP can now either be precipitated in water or a membrane can be prepared directly from the reaction solution. Both the precipitated and the direct casting variant still needs to be post treated in hot to boiling water or post treated with hot steam to obtain thephosphonic acid form (FIG. 4).

Analysis of the Experiment

[0034] Here, one of the phosphonated polymers with different degrees of phosphonation is described as an example including, its ion exchange capacity, conductivity up to 180? C. and an electrolysis test as proof of concept.

Determination of the Ion Exchange Capacity

[0035] 100 mg of the prepared polymer are covered with a saturated NaCl solution and stirred for approximately 2 h, 2 drops of bromothymol blue are added as indicator. The protons of the phosphonated pFKM exchange with the Na ions and HCl is formed. The HCl formed is detected by titration with 0.1 mol NaOH. From this, the IEC.sub.direct can be determined. To determine the total IEC, 3 ml NaOH 0.1 M is added in excess to the same solution, stirred again for another 2 h and then titrated back with HCl.

[0036] For the above described experiment an IEC.sub.direct=0.99 mmol/g and IEC.sub.total=2.62 mmol/g is obtained.

[0037] If the same experiment is carried out with 10 g FKM and 10 g TTMSP, an IEC.sub.direct=0.56 mmol/g and IEC.sub.total=0.8 mmol/g is obtained. This clearly shows the relationship between the reactant ratios, the degree of phosphonation and the conductivity (FIG. 2).

Conductivity

[0038] In FIG. 2, the influence of the degree of phosphonation on the conductivity can be seen well and also that the conductivity does not decrease above 100? C. and thus new types of electrochemical cells, above 150? C., are possible. For comparison to the state of the art, a Nafion 212 with the same measurement conditions is also displayed.

[0039] Proof of concept electrolysis test with IEC.sub.total=2.6 mmol/g membrane

[0040] A membrane was made from the phosphonated polymer with the IEC.sub.total=2.6 mmol/g and this membrane was measured in an electrolysis cell, demonstrating that the application in electro membrane processes is possible (FIG. 3).