Poly(p-phenylene sulfone)

The title polymer has been synthesized in moderate molecular weight by the self-condensation of sodium 4-halobenzenesulfinate at 175 °C in dimethyl sulfoxide. The use of a small amount of 4-fluorophenyl sulfone served to greatly increase the yield of polymer, presumably by acting as an initiator for a chain-type polymerization. The title polymer is highly crystalline (>85%) and poorly soluble in all solvents attempted. The number-average degree of polymerization was estimated to be 10–16 by elemental analysis. No thermal transitions below 500 °C were detected by DSC. The polymer exhibited extremely high and unusual thermal stability when studied by TGA; the onset of significant mass loss occurred at 517 °C in nitrogen and at 555 °C in air. The polymer was characterized by IR and solid-state ¹³C NMR spectroscopy and by X-ray diffraction. Analogous model compounds for the trimer and tetramer were prepared and used to confirm the structure of the polymer.