Synthesis and properties of novel polyimides from sulfonated binaphthalene dianhydride for proton exchange membranes |
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Authors: | Nanwen Li Zhiming Cui Suobo Zhang Shenghai Li |
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Institution: | 1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;2. Graduate School of Chinese Academy of Sciences, Beijing 100039, China;3. State Key Laboratory of Electroanalytical Chemistry, Changchun 130022, China |
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Abstract: | A sulfonated dianhydride monomer, 6,6′‐disulfonic‐4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (SBTDA), was successfully synthesized by direct sulfonation of the parent dianhydride, 4,4′‐binaphthyl‐1,1′,8,8′‐tetracarboxylic dianhydride (BTDA), using fuming sulfuric acid as the sulfonating reagent. A series of sulfonated homopolyimides were prepared from SBTDA and various common nonsulfonated diamines. The resulting polymer electrolytes, which contain ion conductivity sites on the deactivated positions of the aryl backbone rings, displayed high proton conductivities of 0.25–0.31 S cm?1 at 80 °C. The oxidative stability test indicated that the attachment of the ? SO3H groups onto the dianhydride units did not deteriorate the oxidative stability of the SPI membranes. The better membranes were achieved by the copolymerization of nonsulfonated diamine, SBTDA, and BTDA. Copolymer membrane synthesized from hexane‐1,6‐diamine, SBTDA, and BTDA displayed excellent water stability of more than 1000 h at 90 °C, while its proton conductivity was still at a high level (comparable to that of Nafion 117). Furthermore, the novel block copolymer ( II‐b ) displayed higher proton conductivity compared with the random one ( II‐r ) obviously, probably due to the slightly higher water uptake and better microphase separated morphology. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2820–2832, 2008 |
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Keywords: | sulfonated dianhydride sulfonated polyimides proton exchange membranes proton conductivity |
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