New Sulfonated Polystyrene
and Styrene–Ethylene/Butylene–Styrene
Block Copolymers for Applications in Electrodialysis
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Abstract
In this study we prepared blends of polystyrene (PS)
and high-impact
polystyrene (HIPS) with poly(styrene–ethylene–butylene)
(SEBS) triblock copolymer. After sulfonation, blends were used to
fabricate ion-exchange membranes by solvent-casting and subsequent
thermal treatment to obtain homogeneous packing densities. The morphology
and structure of the blends were investigated by scanning electron
microscopy, atomic force microscopy, and FTIR spectroscopy. Furthermore,
the thermal transitions and stability of all the blends were characterized
using calorimetric techniques and compared with those of the individual
polymers. Analyses of the physical properties (i.e., ionic conductivity,
ion-exchange capacity, water uptake, dimensional stability, mechanical
properties, etc.) showed that the performance of the PS-containing
membranes is, in general, higher than that of the HIPS containing
one. Furthermore, the highest sulfonation degree was also found for
the PS/SEBS membranes. The capabilities of the membranes were tested
by investigating the extraction of Na<sup>+</sup> by electrodyalisis.
Comparison of the percentage of extracted ions indicates that the
incorporation of SEBS results in a significant improvement with respect
to membranes made of individual polymers