Highly heat-resistant polyphenylene sulfide

A new simple and convenient method is developed for preparing polyphenylene sulfide. The method is based on generation of the S2- anion from elemental sulfur in the NaOH-hexamethylphosphoric triamide (HMPA) system. Subsequent reaction of the anion with 1,4-dihalobenzenes at 200 degrees C yields polyphenylene sulfide with a molecular weight of up to 6000 in a yield of up to 78%. Addition of formamide to the reaction mixture allows the molecular weight of the polymer to be increased to 40 000, and the yield to be increased to 95%. Resulting polyphenylene sulfide is resistant to heating in air up to 510 degrees C.