Hyperbranched poly(phenylene sulfide) and poly(phenylene sulfone)

Hyperbranched poly(phenylene sulfide) was prepared from 3,4-dichlorobenzenethiol. This monomer was treated with potassium carbonate in an amide solvent, either N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP). Polymerization for 24 h at 100 degrees C in DMF gave a polymer with a MW of 17 kD and a polydispersity of 2.0. Polymerization for 8.5 h at 150 degrees C in NMP gave a polymer with a MW of 16 kD and a polydispersity of 1.5. Addition of 1,3,5-trichlorobenzene as a multifunctional core to the polymerizations gave reduced M-w and lower polydispersity. Addition of I core for every 50 monomers gave a polymer with a M-w of 8.4 kD and a polydispersity of 1.2 in DMF and a polymer with a M-w of 13 kD and a polydispersity of 1.3 in NMP. The polymers were primarily characterized by size-exclusion chromatography with light-scattering detection (which provided the molecular weights and distributions) and by thermal methods. Differential scanning calorimetry (DSC) revealed that the hyperbranched PPS was amorphous with a T-g between 60 and 90 degrees C and no apparent crystallinity. The polymers prepared in DMF had higher T(g)s than those prepared in NMP. Thermogravimetric analysis revealed that the hyperbranched PPS was very thermally stable, with decomposition temperatures between 400 and 450 degrees C in both air and N-2 atmospheres. In air, complete decomposition occurred by about 625 degrees C, while approximately 25% of the mass remained at 700 degrees C under N-2. The hyperbranched PPS could be oxidized to hyperbranched poly(phenylene sulfone). This material was completely insoluble, but could be analyzed by thermal methods. By DSC, the T-g of the sulfone was approximately 155 degrees C, while by TGA the decomposition temperature was 325-375 degrees C in both air and N-2. In air, decomposition was complete by 575 degrees C, while in N-2 about 30% of the mass remained at 700 degrees C. These simple, one-pot approaches to hyperbranched poly(phenylene sulfide) and hyperbranched poly(phenylene sulfone) from commercially available monomers provide an entry to many further studies and applications for these new materials.