Thermally stable nonlinear optical polyurea functionalized by multiple charge-transfer chromophore

A novel high glass-transition temperature (272 °C) polyurea functionalized by a multiple charge-transfer chromophore, 2-{4-[4,5-bis(4-nitrophenyl)imidazolyl]phenyl}-4,5-bis(4-aminophenyl)imidazole, was synthesized. Simultaneous poling and polymerization and the in situ second-harmonic generation (SHG) measurement technique was carried out to evaluate the thermal stability of the poling-induced orientation. The nonlinear optical coefficient d₃₃ of poled polyurea film was 24 pm/V at 1064 nm fundamental wavelength. The SHG signal of the poled polymer film was quite stable below 200 °C and still remained 80% of its initial value after heating at 250 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4297–4301, 2002