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

Using the post-ate coupling reaction in organic solvents, we synthesized tw o series of nonlinear optical (NLO) polyamic acids with four different NLO chromophores. The properties of these polymers were characterized and compa red. We found that increasing the electron withdrawing ability or replacing the benzene ring in the Tc-conjugated system with thiophene will result in the red shift of the maximum absorption band and enhancement of the nonlin ear optical response. (C) 2000 Elsevier Science Ltd. All rights reserved.