The aromatic polyester from diphenolic acid and isophthaloyl chloride was synthesized byinterfacial polycondensation with tetrabutylammonium chloride as phase transfer catalyst. The
structure was characterized by means of FTIR. The poly(DPA-IPC) solution was titrated by aqueousHCl solution. The titration curves were obtained. The trend of reduced viscosity of solution withconcentration was studied. Besides, the stability of poly(DPA-IPC) in aqueous basic solution wasdiscussed.