Preparation of Sulfonated Poly(phthalazinone ether ether ketone) 7a. To a 25 mL three-necked round-bottomed flask fitted with a Dean-stark trap, a condenser, a nitrogen inlet/outlet, and magnetic stirrer was added bisphthalazinone monomer 4 (0.6267 g, 1 mmol), sulfonated difluoride ketone 5 (0.4223 g, 1 mmol), anhydrous potassium carbonate (0.1935 g, 1.4 mmol), 5 mL of DMSO, and 6 mL of toluene. Nitrogen was purged through the reaction mixture with stirring for 10 min, and then the mixture was slowly heated to 140 °C and kept stirring for 2 h. After water generated was azoetroped off with toluene. The temperature was slowly increased to 175 °C. The temperature was maintained for 20 h, and the viscous solution was cooled to 100 °C followed by diluting with 2 mL of DMSO and, thereafter, precipitated into 100 mL of 1:  1 ( v/v ) methanol/water. The precipitates were filtered and washed with water for three times. The fibrous residues were collected and dried at 110 °C under vacuum for 24 h. A total of 0.9423 g of polymer 7a was obtained in high yield of 93%.