Multiblock copolymer, method of preparing the same, polymer electrolyte membrane prepared from the multiblock copolymer, method of preparing the polymer electrolyte membrane, and fuel cell employing the polymer electrolyte membrane

Abstract

A multiblock copolymer includes a polysulfone repeating unit of formula (1) below; a sulfonated polysulfone repeating unit of formula (2) below; and a polydialkylsiloxane repeating unit of formula (3) below, a method of preparing the multiblock copolymer, a polymer electrolyte membrane prepared from the multiblock copolymer, a method of preparing the polymer electrolyte membrane, and a fuel cell including the polymer electrolyte membrane:

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic view of a fuel cell including a polymer electrolyte membrane according to an embodiment of the present invention;

FIG. 2 is the result of ¹H-NMR spectroscopy on a multiblock copolymer including a polysulfone block and a sulfonated polysulfone block prepared in Example 1;

FIG. 3 is the result of ¹H-NMR spectroscopy on an allylated multiblock copolymer including a polysulfone block and a sulfonated polysulfone block prepared in Example 1;

FIG. 4 is the result of ¹H-NMR spectroscopy on a multiblock copolymer prepared in Example 1;

FIG. 5 is a graph of ionic conductivity of a polymer electrolyte membrane prepared in Example 2 with respect to temperature; and

FIG. 6 is a graph showing the crossover of methanol in the polymer electrolyte membrane prepared in Example 2 with respect to temperature

Claims

1. A multiblock copolymer comprising: a polysulfone repeating unit of formula (1) below;a sulfonated polysulfone repeating unit of formula (2) below; anda polydialkylsiloxane repeating unit of formula (3) below:

2. The multiblock copolymer of claim 1, wherein the tetraalkylamine cation includes a C1-C10 alkyl group that is unsubstituted or substituted by at least one fluorine atom.

3. The multiblock copolymer of claim 1, wherein the ratio of l, m, and n is in a range of 100:20-80:1-20.

4. The multiblock copolymer of claim 1, wherein the multiblock copolymer has a weight average molecular weight of 2,000-100,000.

5. The multiblock copolymer of claim 1, having a structure in which blocks consisting of randomly arranged polysulfone repeating units and sulfonate polysulfone are connected by blocks consisting of polydialkylsiloxane repeating units.

6. The multiblock copolymer of claim 1, having a structure in which a block consisting of polysulfone repeating units and a block consisting of sulfonated polysulfone repeating units are connected by a block consisting of polydialkylsiloxane repeating units.

7. The multiblock copolymer of claim 1, having a structure in which a block consisting of polysulfone repeating units and a block consisting of polydialkylsiloxane repeating units are connected by a block consisting of sulfonated polysulfone repeating units.

8. The multiblock copolymer of claim 1, wherein ion conductivity, hydrophobicity, mechanical properties and/or selectivity to a solvent of the multiblock copolymer are selected by selecting a ratio of the polysulfone repeating unit, the sulfonated polysulfone repeating unit and the polydialkylsiloxane in the multiblock polymer.

9. A method of preparing a multiblock copolymer comprising polymerizing: a polysulfone repeating unit of formula (1) below;a sulfonated polysulfone repeating unit of formula (2) below; anda polydialkylsiloxane repeating unit of formula (3) below:

10. The method of claim 9, wherein ion conductivity, hydrophobicity, mechanical properties and/or selectivity to a solvent of the multiblock copolymer are selected by controlling a ratio of the polysulfone repeating unit, the sulfonated polysulfone repeating unit and the polydialkylsiloxane in the polymerizing.

11. The method of claim 9, wherein a structure of the multiblock copolymer is controlled by controlling a sequence of polymerizing.

12. A method of preparing a multiblock copolymer, the method comprising: synthesizing a polymer of formula (4) below having a polysulfone repeating unit and a sulfonated polysulfone repeating unit by polymerizing disulfonate dichlorodiphenylsulfone (SDCDPS), dichlorodiphenylsulfone, and bisphenol A, wherein l and m are integers of 1-200;

13. The method of claim 12, wherein the tetraalkylammonium hydride includes a C1-C10 group that is unsubstituted or substituted by at least one fluorine atom.

14. The method of claim 12, wherein the synthesizing of the polymer of said formula (4) is performed at 170° C. for 4 hours, 160° C. for 48 hours, and then 160° C. for 24 hours in the presence of K2CO3.

15. The method of claim 12, wherein the reacting of the polymer of said formula (4) with the tetraalkylammonium hydride and the ethylenic unsaturated compound is performed in a mixture of an organic solvent and a 12.5N-sodium hydroxide solution.

16. The method of claim 12, wherein the ethylenic unsaturated compound is one of allychloride and 4-vinylbenzyl chloride.

17. A method of preparing a polymer electrolyte membrane, the method comprising: curing the multiblock copolymer of claim 1;soaking the cured multiblock copolymer in an acid solution to allow protonation; andwashing the protonated multiblock copolymer in deionized water.

18. The method of claim 17, wherein the curing is performed at a temperature of 180-220° C. for 30 minutes to 6 hours.

19. The method of claim 17, wherein the acid solution has a concentration of 1.0-2.0 M and is one of a sulfuric acid solution and a hydrochloric acid solution.

20. The method of claim 17, wherein the soaking of the cured multiblock copolymer in the acid solution is performed at a temperature of 70-90° C. for 3-5 hours.

21. A polymer electrolyte membrane prepared by the method of claims 17.

22. A fuel cell comprising the polymer electrolyte membrane of claim 21.

23. A fuel cell comprising a cathode, an anode, and the polymer electrolyte membrane of claim 22 interposed between the cathode and the anode.