Synthesis, freestanding membrane formation, and properties of novel sulfonated hyperbranched polyimides

    loading  Checking for direct PDF access through Ovid

Abstract

A novel six-membered ring hyperbranched polyimide (HBPI) has been synthesized by condensation polymerization of a difunctional monomer, 9,9-fluorenylidenebis(4,1-phenylene)bis(oxy)-4,4′-bis(1,8-naphthalic anhydride) (FBPNA), and a trifunctional monomer, tris(4-aminophenyl)amine (TAPA), at the molar ratio of FBPNA/TAPA = 1:1 in m-cresol at 180°C for 20 h. The resultant HBPI is further modified via end-capping reaction with 4-phenoxy-1,8-anhydride naphthalene (PNA). Post-sulfonation is performed in concentrated sulfuric acid at different temperatures (50, 60, and 70°C) for the pristine HBPI and 50°C for the PNA-modified polyimides to give various sulfonated HBPIs. Freestanding and tough membranes have been successfully fabricated by casting the polymer solutions containing a cross-linker, bisphenol A epoxy resin, at 80°C. The ion exchange capacities of the resultant membranes are in the range of 1.35–2.21 meq g−1 depending on the degree of chemical modification and the sulfonation conditions. Membrane properties such as water uptake, swelling ratio, proton conductivity, and radical oxidative stability are investigated.

Related Topics

    loading  Loading Related Articles