SYNTHESIS AND CHARACTERIZATION OF THERMALLY CROSS-LINKED POLYIMIDE WITH 2ND-ORDER NONLINEAR-OPTICAL CHROMOPHORE

Synthesis of three novel crosslinked polyimides with push-pull azobenz ene group has been developed. 4-Nitro-4'-[N, N-bis (2-aminoethyl)]amin oazobenzene was first prepared, then poly(amic acid) prepolymer, one c rosslinkable component, was obtained by aminolysis of alternating styr ene-maleic anhydride copolymer, alternating thiophene-maleic anhydride copolymer or alternating benzofuran-maleic anhydride copolymer with i t, and at last the crosslinked second-order nonlinear optical polyimid e was synthesized by crosslinking and imidizing poly(amic acid) prepol ymer with corresponding alternating copolymer. The crosslinking and im idizing processes were studied by IR and UV-Vis spectra. The chromopho re density in one of the crosslinkable components, poly(amic acid) pre polymer, and the thermal stability of crosslinked polyimide thin film were measured by UV-Vis spectra.