Effect of temperature and water as additive on the MW and thermal properties of copoly(p-phenylene/biphenylene sulfide)s

Copoly(p-phenylene/biphenylene sulfide)s, PPBS were prepared from sodium sulfide trihydate(Na₂S·3H₂O), p-dichlorobenzene (DCB), and 4,4′-dibromobiphenyl (DBB) comonomers in N-methyl-2-pyrrolidinone (NMP) solvent using an autoclave. The molecular weights of PPBS copolymers were determined by high temperature (210°C) GPC in 1-chloronaphthalene solvent. The reaction temperature had little effect on the molecular weights of PPBS copolymers with water as additive at the level of 3 mol H₂O per 1 mol Na₂S. PPBS copolymer, however, showed maximum molecular weight of M_w = 24.1 × 10³ with the total water content of 9 mol H₂O per 1 mol Na₂S at an optimum polymerization temperature of 270°C. The resulting PPBS copolymer sample showed higher T_g (by 30°C) and lower T_m (by 10°C) than PPS homopolymer prepared under similar conditions. © 1996 John Wiley & Sons, Inc.