Sulfonated poly(meta‐phenylene isophthalamide)s as proton exchange membranes |
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| Authors: | Feilong Liu Daniel M Knauss |
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| Affiliation: | Department of Chemistry, Colorado School of Mines, Golden, Colorado |
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| Abstract: | Random and block sulfonated poly(meta‐phenylene isopthalamide)s as proton exchange membranes were synthesized through the Higashi‐Yamazaki phosphorylation method. Polymers with different degrees of sulfonation from 40 to 100 mol percent were prepared by adjusting the molar feed ratio of 5‐sulfoisophthalic acid sodium salt (SIPA) and isophthalic acid (IPA) in the reaction with meta‐phenylene diamine. Creasable polymer films were obtained by casting DMSO polymer solutions and the membrane films could be exchanged to the proton form in strong acid. 1H NMR spectroscopy and titration confirmed the degree of sulfonation. Thermogravimetric analysis demonstrated good thermal stabilities with 5% weight loss greater than 380 °C. The copolymers with low degrees of sulfonation (DS = 40 mol %) exhibited low water uptake (water uptake < 17 wt %) at room temperature. A segmented multiblock copolymer prepared by preforming a sulfonated block showed lower water uptake at high temperatures than the random polymer with the same DS of 40 mol % and displayed stability in water up to 80 °C. Both random and block copolymers showed higher proton conductivities at high temperature than that of Nafion‐117 under 95% relative humidity. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2582–2592 |
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| Keywords: | membranes step‐growth polymerization polyamides block copolymers proton conductivity |
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