Proton conducting sulfonated polysulfone and polyphenylsulfone multiblock copolymers with improved performances for fuel cell applications
Sydonne Swaby, Nieves Ureña, María Teresa Pérez‐Prior, Carmen del Río, A. Várez, Jean‐Yves Sanchez, Cristina Iojoiu, B. Levenfeld
Abstract
A series of proton exchange membranes based on sulfonated multiblock copolymers with three polysulfone (PSU) and polyphenylsulfone (PPSU) ratios (50/50, 60/40 and 75/25) are prepared following a synthesis strategy that aims to achieve a microphase separation. A selective sulfonation of PSU blocks was observed in copolymers with a high proportion of PSU. The water uptake is higher in these materials (31% and 57% for SPES 50/50 and SPES 75/25, respectively at 60 °C) while the tensile strength was lower (56.0 MPa and 40.6 MPa for SPES 50/50 and SPES 75/25 in the H+ form, respectively). Ionic conductivity of SPES 75/25 membranes measured both ex situ and in situ at 80 °C is 25 and 31 mS·cm−1, respectively. Fuel cell tests reveal that SPES 75/25 shows the highest value for the maximum power density (670 mW·cm−2 at 70 °C and 100% of RH) which is higher than that achieved for SPES 50/50 (400 mW·cm−2). In addition, the high current density obtained for SPES 75/25 (1000 mA·cm−2 at 0.6 V and 70 °C) compared with SPES50/50 (600 mA·cm−2) and Nafion 112 (450 mA·cm−2 at 75 °C) shows its promising properties as solid electrolyte in polymeric fuel cells.