Synthesis and characterization of two series of polyimides as nonlinear optical materials

Using the post-azo coupling reaction in organic solvents, we synthesized two series of nonlinear optical (NLO) polyamic acids with four different NLO chromophores. The properties of these polymers were characterized and compared. We found that increasing the electron withdrawing ability or replacing the benzene ring in the π-conjugated system with thiophene will result in the red shift of the maximum absorption band and enhancement of the nonlinear optical response.