Experimental and theoretical investigations, including an all-atom computer simulation, are performed for block samples of thermoplastic polyimides, amorphous R-BAPS (based on R dianhydride 1,3-bis(3',4-dicarboxyphenoxy)benzene and diamine BAPS 4,4'-bis(4''-aminophenoxy)biphenyl sulfone), and crystallizable R-BAPB (based on R dianhydride and diamine BAPB 4,4'-bis(4''-aminophenoxy) biphe- nyl), which differ in either the presence or absence of the sulfone group in the repeating unit of the polyimide macromolecule. The features of thermophysical, structural, and mechanical properties of R-BAPS and R-BAPB are related to the formation of associates from sulfur and oxygen atoms of the sulfone group that are stabilized by electrostatic interactions.