Thermoplastic and thermoset polyimides derived from 2,2-bis[4-(4-aminophenoxy)phenyl] propane (BAPP) and 4,4'-bis(4-aminophenoxy)-2,2'-dimethylbiphenyl (BAPD) were prepared and characterized. Their physical and thermal properties as well as the polyelectrolyte effect exhibited by BTDA-BAPP polyamic acids in NMP solution were discussed.