Proton conducting sulfonated polysulfone and polyphenylsulfone multiblock copolymers with improved performances for fuel cell applications

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 degrees 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 degrees C is 25 and 31 mS center dot cm(-1), respectively. Fuel cell tests reveal that SPES 75/25 shows the highest value for the maximum power density (670 mW center dot cm(-2) at 70 degrees C and 100% of RH) which is higher than that achieved for SPES 50/50 (400 mW center dot cm(-2)). In addition, the high current density obtained for SPES 75/25 (1000 mA center dot cm(-2) at 0.6 V and 70 degrees C) compared with SPES50/50 (600 mA center dot cm(-2)) and Nafion 112 (450 mA center dot cm(-2) at 75 degrees C) shows its promising properties as solid electrolyte in polymeric fuel cells. (c) 2023 The Authors. Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engi-neering Chemistry. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).

Automated summary

A series of proton exchange membranes based on sulfonated multiblock copolymers with different polysulfone (PSU) and polyphenylsulfone (PPSU) ratios were successfully prepared. The membranes with a higher proportion of PSU exhibited selective sulfonation of PSU blocks. These materials showed higher water uptake and lower tensile strength. Among them, the SPES 75/25 membrane displayed the highest ionic conductivity and maximum power density, making it a promising solid electrolyte for polymeric fuel cells.