Abstract
Linear polyphenylene sulfide has been synthesized by the condensation polymerization of alkali metal salts of p‐halothiophenols. The monomers investigated included the lithium, sodium and potassium salts of p‐bromothiophenol and the sodium salts of p‐fluoro‐, p‐chloro‐, p‐bromo‐, and p‐iodothiophenol. The mass polymerizations of these monomers were carried out below the melting points of the salts and appear to involve a solid state reaction. Rate measurements were made on the polymerization of these monomers in pyridine and on a model of the propagation reaction. In both cases, the order of reactivities of the sodium salts was I > Br > F ∼ Cl, and in the polymerization reaction, the order of reactivities of the alkali metal salts of p‐bromothiophenol was K < Na < Li. Comparison of the rates of the polymerization and model reactions indicates that the reactivities of all functional groups were essentially identical for the iodo and bromo derivatives. However, this comparison indicated that for the chloro and fluoro derivatives, the polymer chain endgroups were more reactive than the monomers. This effect, termed preferential polymer formation, has been verified for the polymerization of sodium p‐fluorothiophenoxide by the determination of unreacted monomer after the polymerization. Complete control of side reactions which lead to chain termination has not as yet been achieved for these condensation polymerization. Linear polyphenylene sulfide is kinetically stable in air and nitrogen up to 400°C. In nitrogen, a residue forms, representing approximately 50% of the original weight of the polymer, which is kinetically stable up to 900°C.