Sulfonated poly(meta‐phenylene isophthalamide)s as proton exchange membranes

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 8C. The copolymers with low degrees of sulfonation (DS 5 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 8C. Both random and block copolymers showed higher proton conductivities at high temperature than that of Nafion-117 under 95% relative humidity.

Synthesis and Characterization of Phenolphthalein‐Containing Sulfonated Poly(arylene ether phosphine oxide)s by Direct Polycondensation for Proton Exchange Membrane

“…Nafion membrane, showing excellent mechanical properties and good chemical stability, is the most frequently used one. Nevertheless, it also presents some drawbacks such as low conductivity at high temperature or low humidity, high cost, and high methanol crossover, which obstruct its wide applications in PEMFCs . Therefore, many aromatic polymer membranes have been developed as alternative PEMs due to their excellent mechanical properties, thermal and chemical stability, high conductivity, and low methanol crossover …”

Preparation and characterization of layer‐by‐layer self‐assembly membrane based on sulfonated polyetheretherketone and polyurethane for high‐temperature proton exchange membrane

“…Proton exchange membrane fuel cell (PEMFC) fueled by hydrogen as a kind of green and efficient energy conversion device has attracted great interests for stationary and mobile applications owing to high power density, high efficiency, low emission power sources, and environmental friendliness . As the key component of PEMFC, proton exchange membranes (PEMs) functioned as a medium to conduct protons from anode to cathode besides acted as a separator between the fuel and oxidant .…”

Thermal stability of end‐capped and linear sulfonated polyimides, sulfonated polystyrene, and Nafion 117

“…Sulfonated aromatic polyamides have also been investigated as potential PEMs for fuel cell technology . For example, Liu and Knauss demonstrated that sulfonated poly(metaphenylene isophthalamide)s with DS of 40% resisted desulfonation at ∼290 °C, a temperature equivalent to SPIs …”

“…There are many more examples of sulfonated polymers such as SPIs, [27][28][29][30][31][32][33][34][35][36][37][38][39][40] sulfonated polybenzimideazoles, 41,42 sulfonated polyphthalazinone, 43 and sulfonated aromatic polyamides. [44][45][46][47][48][49][50][51] A recent review by Ghosh and Banerjee 52 covers a specific area of sulfonated fluorinated-aromatic polymers as an example. The aforementioned examples of sulfonated polymers for PEM fuel cell applications show sulfonic acid decomposition in the range of 200-340 8C, depending on molecular architecture.…”

“…Sulfonated aromatic polyamides have also been investigated as potential PEMs for fuel cell technology. [45][46][47][48][49][50][51] For example, Liu and Knauss 51 demonstrated that sulfonated poly(metaphenylene isophthalamide)s with DS of 40% resisted desulfonation at 290 8C, a temperature equivalent to SPIs. [24][25][26]28 Clearly, in many cases, the influence of polymer backbone structure and the electron affinity of the group or atom bonded to the sulfonic acid were shown to be important contributors to thermal stability.…”