Synthesis, Characterization and Non-linear Optical Properties of Polyimide and Polyimide/Silica Hybrid Materials

A non-linear-optical (NLO) chromophore molecule and polyimide (PI) were synthesized. The chemical structures were characterized by (1)H NMR and elemental analysis. Then, a polyimide/silica NLO hybrid material with covalent links between the inorganic and the organic networks was synthesized using polyimide, 3-aminopropyltriethoxysilane (APTES) as a coupling agent between the organic and inorganic phases, and the hydrolyzate of tetraethyl ortho-silicate (TEOS) by the sol-gel process. FTIR and (29)Si nuclear magnetic resonance spectroscopy were used to characterize the structure of the hybrid. The results revealed that Q(3), Q(4) and T(3) were the major microstructural elements in forming a three-dimensional network structure. The particle size and crystallinity were investigated using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA) exhibited the glass transition temperature (T(g)) and the decomposition temperature (T(d)) of 5% mass loss in polyimide and hybrid material at 244 degrees C and 344 degrees C, 352 degrees C and 447 degrees C, respectively. A reflective electro-optic (EO) modulator using this polyimide or hybrid was fabricated. The electro-optic (EO) coefficients 33 of the polyimide and hybrid in the EO modulator were determined to be 28 and 22 pm/V (poling voltage of 3.8 kV, 205 degrees C) at 832 nm by an attenuated-total-reflectance (ATR) method and the values retained >94% for more than 100 h at 205 degrees C. The results show that polyimide and hybrid may be useful as EO modulator.