The behavior in interfacial polycondensation of 4,4 -methylenedianiline (MDA) or 4,4 -oxydianiline (ODA) in water with dimethoxycarbonylterephthaloyl chloride (DCMTC) in dichloromethane with benzyltriethylammonium chloride (BTEAC) as the catalyst was examined with a Raman imaging microscope, and scanning electron microscope. The surfaces of the polymers adjacent to the water phase had higher average molecular weight than the surfaces of the polymers adjacent to the organic phase. Moreover, the morphology of the films also changed from dense to porous along the thickness direction of the films. To obtain an interfacial film more homogeneous in morphology and molecular weight, the reaction time of interfacial condensation should not exceed 5 minutes in this system. The interfacial films were anisotropic. The chain axis of the poly(amic-ester)s mainly oriented perpendicularly to the interface in the direction of membrane growth.