Sulfonated poly(ether ether ketone)/polybenzimidazole oligomer/epoxy resin composite membranes in situ polymerization for direct methanol fuel cell usages

A diamine-terminated polybenzimidazole oligomer (o-PBI) has been synthesized for introducing the benzimidazole groups (BI) into sulfonated poly(ether ether ketone) (SPEEK) membranes. SPEEK/o-PBI/4,4′-diglycidyl(3,3′,5,5′-tetramethylbiphenyl) epoxy resin (TMBP) composite membranes in situ polymerization has been prepared for the purpose of improving the performance of SPEEK with high ion-exchange capacities (IEC) for the usage in the direct methanol fuel cells (DMFCs). The composite membranes with three-dimensional network structure are obtained through a cross-linking reaction between PBI oligomer and TMBP and the acid–base interaction between sulfonic acid groups and benzimidazole groups. Resulting membranes show a significantly increasing of all of the properties, such as high proton conductivity (0.14 S cm−1 at 80 °C), low methanol permeability (2.38 × 10−8 cm2 s−1), low water uptake (25.66% at 80 °C) and swelling ratio (4.11% at 80 °C), strong thermal and oxidative stability, and mechanical properties. Higher selectivity has been found for the composite membranes in comparison with SPEEK. Therefore, the SPEEK/o-PBI/TMBP composite membranes show a good potential in DMFCs usages.

An approach of introducing the benzimidazole groups (BI) into sulfonated poly(ether ether ketone) (SPEEK) membranes has been proposed to prepare SPEEK/o-PBI/4,4′-diglycidyl(3,3′,5,5′-tetramethylbiphenyl) epoxy resin (TMBP) composite membranes via in situ polymerization. The composite membranes with three-dimensional network structure are obtained through a cross-linking reaction between the o-PBI and TMBP and the acid–base interaction between sulfonic acid groups and benzimidazole groups. The resulting composite membranes show a significantly increasing of all of the properties, such as high proton conductivity, low methanol permeability, low water uptake and swelling ratio, strong thermal and oxidative stability, and mechanical properties.Figure optionsDownload as PowerPoint slide