Patent ID: 8916674

Claim:
A method for preparing terpolymer of poly (diphenyl ether sulfone) and poly (diphenyl ether diphenyl sulfone), the steps are as follows: (1) The method is implemented by adding high-temperature organic solvent to a three-neck flask provided with a thermometer, a nitrogen tube, a condensate water separator and a stirrer, adding 4,4′-dihydroxydiphenyl, 4,4′-dichlorodiphenyl sulfone and 4,4′-Bis(4-chlorophenyl)sulfonyl-1,1′-biphenyl in turn; after all monomers are dissolved, heating to 100° C. and adding alkali metal carbonate salt-forming agent which is 5-10 mol % more than the amount of 4,4′-dihydroxydiphenyl added, and then adding xylene; keeping heating so that the salt-forming reaction of the system begins, wherein the system temperature is controlled between 190° C. and 210° C., and the theoretical value achievement of water yield of the system represents the completion of the first-stage salt-forming reaction; at the moment, raising the system temperature to 230-236° C. and maintaining for 3-4 hours to complete polymerization to obtain a viscous polymer solution; (2) After the reaction stops, injecting the viscous polymer solution directly into distilled water at room temperature to obtain a strip solid; grinding the strip solid into powder and obtaining a solid powder containing a polymer, water-soluble solvent and salt through filtration; adding the solid powder to deionized water of 10 times its weight, boiling away for 1 hour, and removing the water-soluble solvent and salt through filtration; then boiling away the polymer-containing solid powder in the same way 8-10 times until the chloride ion content in the boiled filtrate as detected with silver nitrate is acceptable; vacuum drying the resultant polymer powder until the moisture content by weight is less than 0.5%, when a terpolymer containing chain segments I and II is obtained