Synthesis and electro-optic property of intercalation polyimide and polyimide/ silica

An intercalation nonlinear-optical (NLO) polyimide was synthesized by the ring-opening polyaddition of 4,4´-(Hexafluoroisopropylidene) diphthalic Anhydride (6FDA) and [(6-nitrobenzothiazol-2- yl)diazenyl]phenyl-1,3-diamine. Then, sol-gel technique was adopted, utilizing 3- aminopropyltriethoxysi- lane (APTES) and tetraethoxysilane (TEOS). The polyimide/silica hybrid material was obtained. The polyimide and hybrid were characterized by the methods of FT-IR spectra, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) to get their structure, morphology, thermal performance etc. The results showed that interpenetrating hybrid polymer networks was formed, there were finely dispersed, and existed bond conjunction between organic-inorganic phases. The glass transition temperature (T_g) and the decomposition temperature (T_d) at 5% mass loss were 247, 364degC and 363, 462degC, respectively. These results showed that the hybrid material had excellent thermal stability than the pure polyimide. The polyimide and hybrid solution could be spin coated on the indium-tin-oxide (ITO) glass to form optical quality thin films. The electro-optic coefficients of nonlinear optical polyimide and hybrid were measured at the wavelength of 832 nm. The electro-optic coefficients (gamma₃₃) were 19 and 16 pm/V and the values remained well (retained Gt92% for more than 100 h). The results suggest that the materials have potential applications for high performance optical device.