ELECTRON-PARAMAGNETIC-RESONANCE SPECTROSCOPIC INVESTIGATION OF THE SYNTHESIS OF POLY(P-PHENYLENE SULFIDE/DISULFIDE), PPS/DS

A new process for the synthesis of the commercially important semicrystalline, engineering thermoplastic poly(p-phenylene sulfide/disulfide), PPS/DS, based on the reaction of diiodobenzene and sulfur in air at elevated temperatures (230-300-degrees-C), has been introduced. Since it was anticipated that radicals would play an important role in this process, the reaction was examined by high-temperature electron paramagnetic resonance spectroscopy (EPR). This paper includes the first direct observation of radicals under conditions of PPS/DS synthesis. Radicals observed include both a sulfur radical and a carbon radical. EPR experiments with monomers indicate the importance of polysulfide linkages, such as disulfide, with and without iodine or iodo substitution for the formation of these radical species. Even though these results indicate that radicals are easily formed in our process, comment on the importance of the observed radical species in this polymerization mechanism is impossible.