A nonlinear optical(NLO) azo polyimide has been synthesized by post-polymerization azo coupling reaction．In the process

a new diamine monomer

([2-(N—ethylanilino)-ethoxyl]P—phenylenediamine)

was synthesized and then reacted with 2

2-bis(3

4-dicarboxyphenyl)hexafluomisopropylidene dianhydride(6FDA)to obtain a potyimide—based precursor polymer．The precursor polymer owned excellent solubility in DMSO

DMF and other polar organic solvents．Through post—polymerization azo—coupling reaction of the precursor polymer

the NLO azo polyimide was obtained．This synthetic scheme can avoid exposure of the ago chromophore to the rigorous imiderization conditions required in the synthesis of polyimide．By the scheme

the degree of functionalization of the azo polyimide can reach abort 100％ under mild reacting condition and the product can be easily separated from the solution．The polymer synthesized was characterized by using spectroscopic methods and thermal analysis．The polymer shows good solubility

processibility and thermal—stability．The d33 of the polymer film is 39．2 pm／V．