Nonlinear optical properties of polymers containing a new azophenylbenzoxazole chromophore

The synthesis of the new highly extended chromophore 2-[4-(N,N-dihydroxyethylaminophenylazo)-phenyl]benzoxazole is described. Two polymers obtained by the polycondensation of this chromophore with propyloxyterephthalic acid and 2,4-tolylenediisocyanate and one obtained by the polycondensation of 2-[4-N,N-bis(2-hydroxyethyl)aminophenyl]-6-nitro-benzoxazole with 2,4-tolylenediisocyanate have been prepared and characterized. The polymers are amorphous and exhibit good optical clarity, satisfactory thermal stability above the glass transition temperature and are soluble in common organic solvents. Second order nonlinear optical behavior of the polymers has been studied through measurement of the electrooptic coefficient on films poled between parallel electrodes. The maximum value measured for the electrooptic coefficient (r33) is 6.5 pm/V at an incident laser wavelength of 1.552 μm.