Abstract:A novel aromatic diacid, 3, 5‐dicarboxyl‐4′‐amino diphenyl ether, containing pendant phenoxy amine group was synthesized. Homo‐ and co‐polybenzimidazoles containing different content of pendant phenoxyamine groups were synthesized by condensation of 3,3′‐diaminobenzidine with this acid and a mixture of this acid and isophthalic acid in different ratio in polyphosphoric acid. Copolybenzimidazoles with structural variations were also synthesized based on this acid and pyridine dicarboxylic acid, terephthalic aci… Show more
“…Moreover, the membrane properties can be further improved by introducing benzimidazole ring groups into SPEEK. Polybenzimidazole is a high performance polymer that exhibits good thermal and mechanical properties, as well as benzimidazole rings that possess both donor and acceptor hydrogen bonding sites due to their amphoteric nature [11]- [13].…”
Abstract-A novel Sulfonated Polystyrene (PSS) has been synthesized by sulfonation polystyrene waste for a comparative study of proton exchange membranes (PEM) that is intended for fuel cell applications. The degree of sulfonation (DS) of the sulfonated PS was determined using titration method. We systematically investigated the water uptake, proton conductivity, and methanol permeability of the cross-linked membranes. The mass averaged molecular weights Mw of PSS was estimated from intrinsic viscosities measured in sulfuric acid solutions. A related homopolymer was characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The structures of PSS were elucidated, and the effect of sulfonation level on the PSS FT-IR spectrum was studied. PSS membrane surface morphology was investigated by SEM and AFM.The highest of proton conductivity of the membrane in the temperature range of 25-750C was found to be 3.8 µS/cm Index Terms-AFM, FT-IR, fuel cell, polystyrene sulfonated, SEM.
“…Moreover, the membrane properties can be further improved by introducing benzimidazole ring groups into SPEEK. Polybenzimidazole is a high performance polymer that exhibits good thermal and mechanical properties, as well as benzimidazole rings that possess both donor and acceptor hydrogen bonding sites due to their amphoteric nature [11]- [13].…”
Abstract-A novel Sulfonated Polystyrene (PSS) has been synthesized by sulfonation polystyrene waste for a comparative study of proton exchange membranes (PEM) that is intended for fuel cell applications. The degree of sulfonation (DS) of the sulfonated PS was determined using titration method. We systematically investigated the water uptake, proton conductivity, and methanol permeability of the cross-linked membranes. The mass averaged molecular weights Mw of PSS was estimated from intrinsic viscosities measured in sulfuric acid solutions. A related homopolymer was characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The structures of PSS were elucidated, and the effect of sulfonation level on the PSS FT-IR spectrum was studied. PSS membrane surface morphology was investigated by SEM and AFM.The highest of proton conductivity of the membrane in the temperature range of 25-750C was found to be 3.8 µS/cm Index Terms-AFM, FT-IR, fuel cell, polystyrene sulfonated, SEM.
Polybenzimidazoles containing different contents of pendant nitrophenoxy groups were prepared by condensation of 3,3 0 -diamino-benzidine with a mixture of 3,5-dicarboxyl-4 0 -nitro diphenyl ether and isophthalic acid (IPA) in different ratios in polyphosphoric acid. The polymers are soluble in polar aprotic solvents, they have inherent viscosities in the range of 0.75-1.10 dL g À1 and they form tough and transparent films on solution casting. They have good thermal stability with initial decomposition temperature ranging from 380 to 416 C in nitrogen, good tensile strength ranging from 56 to 65 MPa and reasonably good oxidative stability. Phosphoric acid uptake of these polymers is low compared with PBI and membranes doped with phosphoric acid exhibit good proton conductivity in the range of 6.6Â 10 À3 to 1.9Â 10 À2 S/cm at 25 C and 1.2Â 10 À2 to 4.9Â 10 À2 S/cm at 175 C, compared with 3.9Â 10 À3 S/cm at 25 C and 3.2Â 10 À2 S/cm at 175 C for PBI. These membranes are suitable for applications as polymer electrolyte for fuel cell and presumably for gas separation at high temperature.
“…PBIs were commercially developed by the Celanese Corporation in 1983. PBIs are used for fire-resistant garments, high-temperature stable adhesives, and coatings for aerospace, desalination, and membrane separation [9]. The interaction between the amine protons and the imine nitrogen in the benzimidazole rings is behind their superior mechanical properties [6][7][8].…”
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