Crosslinked Sulfonated Polysulfone-Based Polymer Electrolyte Membranes Induced by Gamma Ray Irradiation

Abstract

Sulfonated aromatic polymers generally show high swelling at high proton conductivity. This disadvantage makes many of them unfit for proton exchange membrane applications. Crosslinking of the polymer is one way to overcome this problem. In this study, radiation-induced crosslinking was performed on a sulfonated polysulfone membrane, with doses ranging from 2.5 to 25.0 kGy (dose rate: 45 Gy/min) using gamma rays from a ⁶⁰Co source. The pristine sulfonated polysulfones was obtained by mild sulfonation of bisphenol-A-polysulfone with trimethylsilyl chlorosulfonate as sulfonating agent. The proton conductivity of the membranes was characterized by means of electrical impedance spectroscopy techniques. Ion-exchange capacity, degree of sulfonation, water content and chemical stability membrane properties were characterized before and after irradiation. The results show that the mechanical, chemical and thermal stability of the membrane improve after irradiation. The degree of sulfonation and the proton conductivity exhibit a tendency to decrease with increasing irradiation total dose.

Keywords:

• crosslinking
• membrane
• polymer electrolyte
• radiation
• sulfonated polysulfone

The authors wish to thank BASF for the PSF materials they provided, the CTEx for the laboratory support, the CNPq for financial support and the Laboratory of Nuclear Instrumentation – Professor Edgar Francisco de Jesus – COPPE, Federal University of Rio de Janeiro.