Synthesis and characterization of poly(phenylene sulfide ether) by reduction of poly(phenylene sulfoxide ether sulfide ether) precursor

Abstract

Poly(phenylene sulfide ether) (PPSE) with increased molecular weight was synthesized by means of the quantitative conversion of a poly(phenylene sulfoxide ether sulfide ether) (PPSOESE) precursor via a modified reduction method. PPSOESE precursor was prepared in good yield using polycondensation reaction between bis(4-fluorophenyl) sulfoxide (BFPSO) and bis(4-hydroxyphenyl) sulfide (BHPS). The effects of reaction conditions on the synthesis of PPSOESE and its conversion to PPSE were examined and the conditions were optimized. The results showed that the solvent, reaction temperature, and total monomer concentration are important factors affecting the yield and molecular weight of PPSOESE. For the reduction of PPSOESE to PPSE, the solvents and the feeding rate of the reducing reagent are key factors controlling the quantitative conversion of sulfoxide to sulfide. Structural characterization displayed that PPSOESE is amorphous and has the desired linear structure, and the derived PPSE is semicrystalline with low crystallinity. The study indicated that alternative introduction of ether units induces a gauche conformation relative to that of poly(phenylene sulfide) (PPS), resulting in crystallinity depression. PPSE with a number-average molecular weight of 1.7 × 104 g mol−1 was obtained in 92.4 % yield, which was much higher than that previously reported for PPSE. Thermal analyses showed that the glass transition temperature (Tg) and the melting temperature (Tm) of the obtained PPSE are 92 °C and 192 °C, respectively. Thermogravimetric analysis indicated that PPSE has high thermal stability with a degradation onset temperature above 470 °C.