Multi-acid polymers and methods of making the same

1. A method of making a multi-acid polymer comprising:

reacting a polymer precursor in sulfonyl fluoride or sulfonyl chloride form with anhydrous ammonia to obtain a sulfonamide, wherein the polymer precursor in sulfonyl fluoride or sulfonyl chloride form has a formula R—SO 2 F or R—SO 2 Cl, respectively, with R being one of more units of the polymer precursor without sulfonyl fluoride or sulfonyl chloride, and wherein the sulfonamide has a formula R—SO 2 —NH 2 ; and

reacting the sulfonamide with a compound of a formula COOH—X-AGG under a mild base condition, wherein X is one of C 6 H 3 or N(CH 2 ) 3 and AGG is an acid giving group, to form the multi-acid polymer having an imide base and more than two proton conducting groups.

2. The method of claim 1 , wherein reacting the sulfonamide with the compound comprises:

soaking the sulfonamide in a solvent;

adding a base to form the mild base condition;

adding the compound; and

reacting at a temperature of 100° C. or less for a period of time.

3. The method of claim 2 , wherein the period of time is greater than twelve hours.

4. The method of claim 1 , wherein the compound is 3,5-Bis(fluorosulfonyl) benzoic acid having a formula of HOOC—C 6 H 3 —(SO 2 F) 2 , where X=C 6 H 3 and AGG=(SO 2 F) 2 .

5. The method of claim 4 , wherein reacting the sulfonamide with 3,5-Bis(fluorosulfonyl) benzoic acid produces an intermediate product:

the method further comprising hydrolyzing the intermediate product with a base and an alcohol, then ion exchanging the intermediate product with an acid to form the multi-acid polymer with the following formula, with R being the one of more units of the polymer precursor without sulfonyl fluoride or sulfonyl chloride:

6. The method of claim 5 , further comprising:

forming a membrane for a fuel cell from the multi-acid polymer by:

converting any remaining sites of the multi-acid polymer to acid form by ion-exchanging the multi-acid polymer with sulfuric acid solution to form the membrane.

7. The method of claim 1 , wherein the compound is selected from the following group: Tris(phosphonomethyl) cyclen; 8-Acetoxy-pyrene-1, 3, 6-trisulfonyl chloride; 3, 6, 8-tris chlorosulfonyl pyrene-1-yl-acetate; 7-ethoxycarbonyloxy-naphthaline-1,3,6-trisulfonyl chloride; 3,5-bis(chlorosulfonyl) benzoic acid; 3,5-bis(chlorosulfonyl)-2-hydroxybenzoic acid; and 3,5-bis(chlorosulfonyl)-,methyl ester benzoic acid.

8. The method of claim 1 , wherein the compound is N,N-Bis (phosphono methyl) glycine having a following formula, wherein X=N(CH 2 ) 2 and AGG=(PO 2 H 2 + ) 2 :

9. The method of claim 8 , wherein reacting the sulfonamide with the N,N-Bis (phosphono methyl) glycine produces the multi-acid polymer with a following formula, with R being one of more units of the polymer precursor without sulfonyl fluoride or sulfonyl chloride:

10. The method of claim 9 , further comprising:

forming a membrane for a fuel cell from the multi-acid polymer by:

converting any remaining sites of the multi-acid polymer to acid form by ion-exchanging the multi-acid polymer with sulfuric acid solution to form the membrane.

11. The method of claim 1 , wherein the compound is selected from the following group: 4-hydroxy-4,4-diphosphonobutanoic acid; 1-amino-1,1-diphosphono-2-carboxy ethane; 2,3-Diphosphono-propionsaeure; Acetic acid,diphosphono-,1-ethyl ester; 2-hydroxy-2,3,4-triphosphonobutanoic acid; 2-hydroxy-2,3,4-triphosphonobutanoic acid; 4-hydroxy-4,4-diphosphonobutanoic acid; 2-hydroxy-2,3-diphosphonopropanoic acid; 3-(1,1-diphosphonoethylamino)-2-hydroxypropanoic acid; 3-amino-2-methyl-3,3-diphosphonopropanoic acid; 2-hydroxy-2,3-diphosphonopropanoic acid; 4,4-diphosphonobutanoic acid; 4-hydroxy-4,4-diphosphonobutanoic acid; Propanoic acid,3,3-diphosphono-,1-ethyl ester; 1-amino-1,1-diphosphono-2-carboxy ethane.