Hyperbranched Poly(Phenylene Sulfide) and Poly(Phenylene Sulfone): Polymerization of 3,5‐Dichlorobenzenethiol

ABSTRACT Hyperbranched poly(phenylene sulfide) was prepared from 3,5‐dichlorobenzenethiol 1 and compared to polymers previously prepared from 3,4‐dichlorobenzenethiol. Compound 1 was polymerized with K 2 CO 3 in N ‐methylpyrrolidone (NMP) at 150°C. Polymerization for 6 h (150°C, NMP) gave a M w of 15.0 kD and a polydispersity of 1.3. Addition of 1,3,5‐trichlorobenzene 2 as a multifunctional core to the polymerization reduced the M w and lowered the polydispersity: addition of 1 core for every 50 monomers gave a M w of 8.2 kD and a polydispersity of 1.2. Addition of 2‐naphthalenethiol 3 to the polymerization as an end‐capping agent also lowered the M w to 12.6 kD, but the polydispersity remained at 1.3. The polymers were characterized by size exclusion chromatography with light scattering detection, by elemental analysis and by thermal and spectroscopic methods. Differential scanning calorimetry (DSC) revealed that this hyperbranched PPS was amorphous. The T g as a function of M n followed the Flory–Fox relation, with a theoretical maximum T g of 78.5°C; the highest observed T g was 74°C. Thermogravimetric analysis (TGA) revealed high thermal stability, with decomposition temperatures ( T d ) above 425°C in both air and N 2 atmospheres. The T d values in N 2 were slightly higher than in air. In air, complete decomposition occurred by ~650°C, while under N 2 a residue of approximately 20% remained at 700°C. The hyperbranched PPS was oxidized to hyperbranched poly(phenylene sulfone). This material was only sparingly soluble but was analyzed by thermal methods. By DSC, the T g of the sulfone was around 203°C, while in TGA the T d was around 430°C in both air and N 2 . In air, decomposition was complete by 575°C, while in N 2 it was complete at 650°C. These simple, one‐pot approaches to hyperbranched poly(phenylene sulfide) and hyperbranched poly(phenylene sulfone) from commercially available monomers provide a further entry to these materials.