A family of engineering thermoplastic resins characterized by the sulfone [SO2] group. Polysulfone is made by the reaction of the disodium salt of bisphenol A[(CH3)2C(C6H4OH)2] with 4,4'- dichlorodiphenyl sulfone 4,4'-DCDPS [(C6H4Cl)2SO2]. Polyethersulfone is made by the reaction of 4,4'-DCDPS with potassium hydroxide [KOH]. Polyphenylsulfone is similar to the other sulfone polymers. Typical applications for sulfone polymers are electrical/electronic uses and automotive parts.