Method for nitrating and aminating an aryl polymer
View Patent ↗The invention relates to a novel and inexpensive process for the nitration and amination of aryl polymers and also to their use as blend components for producing polymer blend membranes. Such polymer blend membranes are used in membrane processes, in particular as polymeric electrolyte in electromembranes, e.g. for electrodialysis and fuel cells.
1. A process for preparing a nitrated aryl polymer comprises the steps of:
a) dissolving aryl polymer in concentrated sulfuric acid at a temperature below 25° C.
b) adding concentrated nitric acid at a temperature below 25° C.
c) precipitating the resulting nitrated aryl polymer in water and separating off the precipitated nitrated aryl polymer, and
d) sulfonating the nitrated aryl polymer by addition of a sulfonating agent in the presence of an anhydride of a carboxylic acid wherein the sulfonating step is carried out at a temperature below 25° C.
2. The process according to claim 1 , further comprising washing a number of times the nitrated aryl polymer obtained in step c) until freed of adhering acid.
3. The process according to claim 1 , further comprising stirring the reaction mixture at temperatures below 25° C. for a further period of up to 10 hours after the addition of nitric acid is complete and before step c) is carried out.
4. The process according to claim 1 , further comprising dissolving the aryl polymer in concentrated sulfuric acid at temperatures of from 0 to 5° C.
5. The process according to claim 1 , wherein the nitration is carried out at temperatures of from 5 to 25° C.
6. The process according to claim 1 , wherein the aryl polymer comprises aromatic building locks selected from the group consisting of
and thermally stable linking units selected from the group consisting of
7. The process according to claim 6 , wherein the aryl polymer further comprises polyether sulfone (PES), polyether ether sulfone (PEES), polyether ketone (PEK), polyether ether ketone (PEEK) or polyether ether ketone ketone (PEEKK).
8. The process according to claim 1 , further comprising dissolving the nitrated aryl polymer obtained in step c) in an aprotic polar solvent and reducing same by means of a reducing agent thereby giving an aminated aryl polymer.
9. The process according to claim 8 , wherein the aprotic polar solvent being selected from the group consisting of dimethylformamide (DMF), dimethylacetate (DMAc), dimethyl sulfoxide (DMSO) or N-methylpyrrolidone (NMP).
10. The process according to claim 8 , wherein the reducing agent being sodium dithionite (Na 2 S 2 O 4 ).
11. The process according to claim 8 , wherein reducing being carried out at temperatures of from 60 to 180° C.
12. The process according to claim 1 , wherein block polymers are obtained.
13. A substituted polyether sulfone or substituted polyether ether sulfone of the formulae (A) and (B) or in the form of a corresponding block polymer of the formula (C)
where X is oxygen or hydrogen and m and n are each a number in the range from 1 to 100.
14. A blend component for producing blend membranes for membrane processes such as fuel cells, for filtration and/or gas separation which is made by the process as claimed in claim 1 .