The enhanced thermal, hydrolytic, and chlorine stabilities of polysulfones enable high performance membranes for water purification technologies. However, poor solvent resistance, which is attributed to the lack of crystallinity, limits the potential commercial impact of polysulfones. On the other hand, semi-crystalline polyesters exhibit superior solvent resistance compared to polysulfones, and copolymerization of polysulfones with semi-crystalline polyesters suggests an unprecedented family of high performance, multiphase thermoplastics. A solvent-free, melt polycondensation to afford segmented polysulfone-containing polyesters involved quantitative end-capping of phenol-terminated polysulfone (PSU) with ethylene carbonate to generate telechelic oligomers with primary hydroxyl functionality. Subsequent melt transesterification of dimethyl terephthalate and 1,4-butanediol in the presence of end-capped, PSU oligomers yielded high molecular weight segmented block copolymers with alternating PSU and poly(butylene terephthalate) (PBT) sequences. The PBT segment length and thermomechanical properties were dependent on PSU incorporation. Complementary DSC, SAXS, and WAXD revealed a miscible amorphous PSU and PBT phase, while PBT crystallinity was maintained below 80 wt.% PSU. Furthermore, the incorporation of PSU segments significantly affected crystallization and thermomechanical properties; DMA revealed a crystallinity-dependent plateau above the composition-dependent glass transition temperature (<i>T</i><sub>g</sub>). As a result, the addition of a semi-crystalline morphology into PSUs maintained thermal stability, obtained higher temperature operating windows, and offer potential impact as chemically resistant, high-temperature thermoplastics.

Sequencing in step-growth polymerization: Influence of segment length on thermomechanical properties of polysulfone-containing segmented polyesters

249th National Meeting (2015)

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