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 hours at 100 oC in DMF gave a polymer with a Mw of 17 kD and a polydispersity of 2.0. Polymerization for 8.5 hours at 150 oC 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 Mw and lower polydispersity. Addition of 1 core for every 50 monomers gave a polymer with a Mw of 8.4 kD and a polydispersity of 1.2 in DMF and a polymer with a Mw 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 Tg between 60 and 90 oC and no apparent crystallinity. The polymers prepared in DMF had higher Tg’s than those prepared in NMP. Thermogravimetric analysis revealed that the hyperbranched PPS was very thermally stable, with decomposition temperatures between 400 and 450 oC in both air and N2 atmospheres. In air, complete decomposition occurred by about 625 oC, while approximately 25% of the mass remained at 700 oC under N2. 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 Tg of the sulfone was approximately 155 oC, while by TGA the decomposition temperature was 325-375 oC in both air and N2. In air, decomposition was complete by 575 oC, while in N2 about 30% of the mass remained at 700 oC. 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.
- hyperbranched polymers
Available at: http://works.bepress.com/dr_james_hanson/3/