A green and efficient synthetic strategy for the preparation of PBS ionomers with high molecular weight, high ionic group content and good combined properties

The conventional direct esterification and polycondensation is difficult to obtain kilogram scale of poly(butylene succinate) (PBS) ionomers with both high molecular weight and high ionic group content. Therefore, the investigation of relationship between the content of ion group and performance (such as mechanical properties) is impossible. In this work, the preparation of PBS ionomers with high molecular weight and high ion group content was achieved by transesterification method using sodium dimethyl isophthalate-5-sulfonate (SIPM) as the ionic monomer, and the polycondensation time decreased significantly with the increase of SIPM content. The mechanism of reducing the polycondensation time of PBS prepared by transesterification is proposed. The tensile strength, flexural strength and impact strength of PBS ionomers increased significantly with increasing SIPM content. At high ion group content, the formed multiplets-clusters among ion groups, which act as reversible physical crosslinking points and nano-fillers, substantially improved the mechanical properties. The tensile strength, flexural strength and impact strength improved and reached to 50.1 MPa, 40.9 MPa and 13.1 kJ/m2 at high ion group content from 34.2 MPa, 24.1 MPa and 5.8 kJ/m2 for PBS, respectively. It showed a totally opposite trend from the previous research. In addition, the hydrophilicity and processing properties of PBS ionomers improved significantly with the increase of the ion group content, and the contact angle reduced to 41.1° after the introduction of ions.