The synthesis and electro-optic properties of polyimide/silica hybrids containing the benzothiazole chromophore

摘要

A series of polyimide/silica NLO hybrid materials were synthesized from pyromellitic dianhydride,2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane,nonlinear optical molecule 4-(N-2-hydroxyethyl-N-methylamino)-4'-[(6-nitrobenzothiazol-2-yl)diazenyl]azobenzene via a sol-gel process;the tetraethoxysilane content in the hybrid films was varied from 0 to 22.5%.The prepared polyimide/silica hybrids were characterized by FT-IR,differential scanning calorimeter,thermogravimetric analysis,scanning electron microscopy,transmission electron microscope and X-ray diffraction.The glass transition temperature and decomposition temperature at 5% mass loss were in the range 214-360°C and 317-428°C,respectively,showing that the hybrid materials had excellent thermal stability.Polymer solutions were spin-coated on indium-tin-oxide glass,forming optical quality thin films.The electro-optic coefficients at 832 nm for poled polymer thin films were approx=20 to 33 pm/V and the values were retained>88% for more than 100 h.The experimental results suggest that the hybrid thin films have potential applications as passive films for optical devices.