Sulfonated aromatic copoly(ether–amide) membranes II

Abstract

Several aromatic sulfonated copoly(ether–amide)s, based on the aromatic diamines 4,4′-(hexafluoroisopropylidene)bis(p-phenyleneoxy)-dianiline (HFD) and 2,4-diaminobenzensulfonic acid (DABS) and 4,4′-oxybis(benzoic acid) (OBA), were synthesized through a polycondensation reaction. The sulfonation degree was controlled by introducing different concentrations of 2,4-DABS from 40 mol% up to 80 mol%. Proton nuclear magnetic resonance validated the expected concentrations of sulfonic acid groups in the sulfonated aromatic copoly(ether–amide)s. Thermal decomposition of sulfonic groups was found to initiate at 280°C, while main chain decomposition initiates at 410°C. Proton conductivity between 30°C and 75°C was 19.0 and 45.0 mS/cm, respectively, for the copolymer with the highest concentration of sulfonic groups (–SO3H). Comparison with structurally similar sulfonated copolyamides and copoly(ether–amide)s indicates that these new sulfonated copoly(ether–amide)s based on 4,4′-OBA show improved mechanical properties, but a decrease in ion exchange capacity and proton conductivity.

Layer‐by‐layer approach to enable polyamide formation on microporous supports for thin‐film composite membranes

“…A potential benefit of LbL sequential deposition is that the approach may circumvent some of the thermodynamic and/or kinetic limitations that are inherent to the conventional interfacial polymerization process. These limitations may restrict options for incorporating different monomers or mixtures of co‐monomers into the PA selective layer 24 . For example, a sulfonated polyamide, in principle, could be prepared via interfacial polymerization using a mixture of MPD and MPDSK diamines in the aqueous phase along with TMC in the organic phase.…”

“…These limitations may restrict options for incorporating different monomers or mixtures of co-monomers into the PA selective layer. 24 For example, a sulfonated polyamide, in principle, could be prepared via interfacial polymerization using a mixture of MPD and MPDSK diamines in the aqueous phase along with TMC in the organic phase.…”