Preparation and Characterization of Hyperbranched Poly (Ether Sulfone)s with Imidazolium Salts at Termini

Abstract

Hyperbranched poly (ether sulfone)s with imidazolium salts at the termini (HBPES-Im) was synthesized by polycondensation of AB2 type monomers and terminal modification using cation exchange reaction. Then, poly (ether ether ether sulfone)s with imidazolium salts at the side chains (PEEES-Im) was prepared to make the composite membranes. HBPES-Im and PEEES-Im were designed each three kind polymers with different terminal structures. The temperatures at which 5% weight losses (T_d5) of HBPES-Im and PEEES-Im occurred were higher than those of each precursors. HBPES-Im(H,H) and PEEES-Im(H,H) without alkyl chains were also high glass transition temperature (T_g). Blend membranes with HBPES-Im and PEEES-Im were prepared by solution casting method and measured ion conductivities by two-probe conductivity measurement. The blend membrane composed of HBPES-Im(H,H) and PEEES-Im(H,H) showed higher ion conductivity of 2.19X10^-3 S/cm under 80 °C and 90% of relative humidity.