Poly(arylene ether sulfone) oligomers have been synthesized by nucleophilic aromatic substitution using potassium carbonate as base and N-methyl pyrrolidinone (NMP) as solvent. m-Aminophenol was used as an endcapper to control the molecular weight of the oligomers and to provide functional amine termination. These amine terminated oligomers can then be utilized in a variety of post reactions. Poly(arylene ether sulfone)-Polyimide segmented copolymers were synthesized using a solution imidization procedure with NMP as the solvent and o-dichlorobenzene as the azeotroping agent. The polysulfone oligomers were reacted into the system via the diamine oligomer. The segmented copolymers demonstrated good solubility characteristics, high thermal stability, and high glass transition temperatures. Previously, polyimides containing pyromellitic dianhydride (PMDA) did not remain soluble in the NMP solvent during the solution imidization, but rather precipitated out of solution when partially imidized. Incorporation of the amine terminated polysulfone oligomers into PMDA containing copolymers resulted in Systems that remained soluble even after completion of imidization. The resulting copolymers were completely soluble in many of the high boiling solvents. The copolymers demonstrated high thermal Stability and high glass transition temperatures. / Master of Science