Radiation-induced crosslinking of poly(styrene–butadiene–styrene) block copolymers and their sulfonation

• The c-SBS films were prepared using a gamma ray or electron beam.
• The crosslinking degree of the c-SBS films were increased with the irradiation dose.
• The prepared c-SBS films were sulfonated with various concentration of CSA.
• The sulfonation of the c-SBS film is largely dependent on the concentration of CSA.
• The sulfonation process is progressed from the surface to the inner part of c-SBS film.

Several crosslinked poly(styrene–butadiene–styrene) (c-SBS) block copolymer films were prepared using a gamma ray or electron beam with various irradiation doses and the prepared c-SBS film was then subjected to sulfonation using a chlorosulfonic acid (CSA) solution to introduce a sulfonic acid group. To estimate the degree of crosslinking, the gel fractions and FT-IR spectra of the c-SBS films were used and the results indicate that the degree of crosslinking is increased with an increase in the radiation dose. The surface morphology and mechanical property of the c-SBS films were observed using SEM and UTM instruments, respectively. The sulfonated c-SBS films were investigated by measuring the ion exchange capacity (IEC) and by observing the cross-sectional distribution patterns of sulfonic acid group using an SEM-EDX instrument. The IEC and SEM-EDX studies indicate that the sulfonated c-SBS membranes can be successfully prepared through the radiation crosslinking of the SBS film and the subsequent sulfonation with a diluted CSA solution.