Synthesis and Characterization of Polysulfone-Containing Poly(butylene terephthalate) Segmented Block Copolymers

Abstract

A facile synthetic approach to segmented polysulfone-containing polyesters affords a versatile family of high-temperature thermoplastics with tunable thermomechanical properties. End-capping of phenol-terminated polysulfone (PSU) using ethylene carbonate generated telechelic oligomers with primary alcoholic functionality. Melt transesterification of dimethyl terephthalate and 1,4-butanediol in the presence of PSU oligomers yielded high molecular weight segmented block copolymers with alternating PSU and poly­(butylene terephthalate) (PBT) sequences. Systematic variation in PSU incorporation resulted in tunable PBT segment length and accompanying thermal properties. DSC and SAXS elucidated a miscible, amorphous PSU and PBT phase, and PBT crystallinity remained below an 80 wt % incorporation of PSU. Dynamic mechanical analysis (DMA) revealed a crystallinity-dependent plateau regime above the copolymers glass transition temperature (<i>T</i>_g), while SAXS and WAXD confirmed a semicrystalline morphology below 80 wt % PSU. Incorporation of PSU segments significantly affected the crystallization and thermomechanical properties of PBT, and as a result these copolymers offer impact as chemically resistant, high-temperature thermoplastics due to their crystallinity, thermal stability, and high-temperature operating window