Effect of in situ oxidization with potassium permanganate on the morphologies of SEBS membranes

The morphologies of the asymmetric membranes of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) prepared and simultaneously oxidized with different substrate solutions were investigated with atomic force microscopy (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATR-FTIR). We used the KMnO4 aqueous solution and KMnO4/H2SO4 mixture solution as solvent-casting substrates, as well as oxidized reagents. The surface composition and functional groups of membranes were also measured. The effect of casting substrates on morphological changes was discussed through possible chemical reactions. It was found that the SEBS membranes were transformed from an ordered microphase-separated structure to disordered nodular or sponge-like structures. The former might be contributed to MnO2 depositions while the latter was caused by the bond interruption, after KMnO4 or KMnO4/H2SO4 oxidizing.