MECHANISM OF POLY(PARA-PHENYLENE SULFIDE) GROWTH FROM PARA-DICHLOROBENZENE AND SODIUM SULFIDE

The chemistry of poly(p-phenylene sulfide) (PPS) growth from Na2S and p-dichlorobenzene in NMP is dominated by the ionic S(N)Ar mechanism. Consistent with this mechanism are model reactions that obey discrete second-order reaction kinetics in both independent and competition experiments. Reaction rates are as well affected by substituents in a fashion predicted by the S(N)Ar mechanism. Diagnostic reactions to probe radical mechanisms provide no evidence for radical intermediates with the possible exception of certain anomalous side reactions. The unusual behavior of the growth of high molecular weight PPS at low conversions is totally explained in terms of discrete ionic reaction rates. NMP not only facilitates the S(N)Ar chemistry through its dipolar aprotic properties but also functions as a catalytic reactant in transforming Na2S into a soluble nucleophile.