New semi-rigid poly(ester-imide)s with cyanoazobenzene side chains were prepared by melt polycondensation of a diethyl isophthalate derivative of cyanoazobenzene with N,N'-dihexanols of five aromatic diimides in the presence of zinc acetate. Differential scanning calorimetry (DSC) measurements and polarizing microscope observations demonstrated that the polymers have glass transitions (T-g) between 46 and 93 degrees C and show no liquid crystalline (LC) properties. All poly(ester-imide)s generated optical phase-conjugate (PC) signals at high reflectivity by degenerate four-wave mixing (DFWM) at low pump-beam power.