Synthesis, Characterization and Properties of Novel Amphiphilic Phosphated Ionomers by Ring‐Opening Reaction of Epoxidized Styrene‐Butadiene‐Styrene Triblock Polymer

Abstract

A method for synthesis of novel phosphated ionomer of (styrene-butadiene-styrene) triblock polymer (SBS) from epoxidized SBS was developed. The optimum conditions for the ring-opening reaction of the epoxidized SBS with aqueous solution of disodium hydrogen phosphate were studied. It was found that during the ring-opening reaction phase transfer catalyst, ring-opening catalyst and pH regulator were necessary to enhance the conversion of epoxy groups to ionic groups. The products were characterized with Fourier Transform Infrared Spectrophotometry (FTIR) and transmission electron microscopy (TEM). Some properties of the phosphated ionomer were studied. With increasing ionic groups or the ionic potential of the cation of the ionomer, the water absorbency emulsifying volume and the intrinsic viscosity of the ionomer increase, whereas the oil absorbency decreases. The ionomer possesses excellent emulsifying property, as compared with the sulfonated ionomer. The disodium phosphated ionomers in the presence of 10% zinc stearate showed better mechanical properties than the original epoxy SBS. Optimum mechanical properties occurred at the ionic group content of 0.95 mmol/g ionomer. When the ionomer was blended with crystalline polypropylene, a synergistic effect occurs with respect to the tensile strength. The ionomer behaves as a compatibilizer for blending equal amount of SBS and oil-resistant chlorohydrin rubber (CHR) to form an oil resistant thermoplastic elastomer. SEM microphotographs indicated enhanced compatibility between the two components of the blend in the presence of the ionomer.