Preparation, morphological characteristics and electro-optic property of polyimide and hybrid

Nonlinear optical (NLO) polyimide and a series of polyimide/silica nanohybrids were synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), NLO molecule 4-(4’- nitrophenyl-2-yl) phenyl-1,3-diamine, coupling agent and TEOS via sol-gel method. The TEOS content in the hybrids was varied from 0 to 22.5 wt%. The prepared hybrids were characterized by FT-IR, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). The glass transition temperature (Tg) and the decomposition temperature (Td) at 5 % mass loss were in the range 232~365 °C and 335~475 °C, respectively. The results showed that the prepared materials had excellent thermal stabilities. The electro-optic coefficients (γ33) at 832 nm were in the range of 19-34 pm/V and the values remained well. The experimental results indicate that the prepared thin films have good candidate for electro-optical applications.