meta-Aminophenol was used during nucleophilic step copolymerization to end-cap partially disulfonated bisphenol A based random copolymers with controlled oligomeric molecular weights. The amine end groups were thermally reacted with a tetrafunctional epoxy reagent to produce networks. Very high gel fractions, up to 99%, and ductile film formation were achieved. The oligomer was further functionalized with acryloyl chloride, phenylethynyl phthalic anhydride, and maleic anhydride to obtain several novel free radically cross-linkable oligomers. The structure and molecular weights (M n) were established with 1H NMR spectroscopy of the oligomers and end groups. TGA analysis demonstrated the high thermal stability of these oligomers; DSC investigations showed that the oligomers had curing exotherms from 140 to 330 °C and that residual casting solvent during cross-linking was necessary to avoid vitrification during membrane formation. In addition to the thermally cross-linkable systems, photocross-linking was demonstrated with the telechelic acrylamide functionalized oligomers. Two compositions were identified as potential candidates for further development. Cross-linking disulfonated poly(arylene ether sulfone) copolymers limits the high water sorption and swelling of these hydrophilic materials, which enhances several properties for membrane applications. Initial transport results indicate that cross-linking greatly reduces salt permeability while modestly decreasing water permeability, resulting in improved water/NaCl selectivity.

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Disulfonated poly(arylene ether sulfone) random copolymers with controlled oligomeric molecular weights were synthesized via nucleophilic aromatic substitution step polymerization. A monofunctional endcapping reagent, meta-aminophenol, was utilized to control the molecular weight of the oligomers and to install telechelic amine endgroups. The meta-aminophenol endcapped oligomers were reacted with acryloyl chloride to obtain novel crosslinkable poly(arylene ether sulfone) oligomers with acrylamide groups on both ends. The chemical compositions of the functional oligomers were characterized by 1 H NMR spectroscopy to determine the degree of sulfonation and concentrations of acrylamide endgroups. The acrylamide-terminated oligomers were crosslinked with UV radiation in the presence of a multifunctional acrylate and a UV photoinitiator. Transparent, free-standing, dense films were obtained with high gel fractions. FTIR spectroscopy was utilized to observe the progress of the photo-crosslinking reaction. Thin films were cast from either aqueous or water-methanol solutions. The crosslinked disulfonated poly(arylene ether sulfone) networks exhibited reduced water uptake and swelling relative to their linear counterparts. SEM and AFM showed that the photo-crosslinked thin films had smooth surfaces.