Add time:09/28/2019         Source:infona.pl

A new series of six-membered ring sulfonated polyimides with different combinations of two comonomers in the nonsulfonated diamine was prepared by one-step high-temperature polycondensation in m-cresol to improve the solubility of the resulting sulfonated polyimides. They are based on 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminostilbene-2,2-disulfonic acid sulfonated diamine, and equimolar mixture of 3,5,3′,5′-tetramethylbenzidine (TMB) and 4,4′-oxydianiline, bis(4-aminophenyl)methane, or bis(4-(aminophenoxy)-4-phenyl)isopropylidene nonsulfonated diamines. The introduction of TMB comonomer in the nonsulfonated diamine resulted in a remarkable improvement in the solubility of the resulting polyimides in comparison with the corresponding single-monomer nonsulfonated diamine polyimides. Flexible, transparent, and tough membranes were prepared by solution casting method from the different polyimides. The membranes were characterized with FTIR and 1H-NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, water uptake, and ion-exchange capacity measurements. They exhibit high thermal stability and good correlation between the ion-exchange capacity and water uptake values.

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