Study Of Fluorine-Containing Polyimide Organic-Inorganic Hybrid Materials With Nonlinear Optic Characteristics

Abstract: In order to prepare optical polymer materials with high nonlinear activity and thermal stability, a series of polyimide organic/inorganic hybrid materials were successfully synthesized and their properties were studied in this dissertation.In this paper,azo and benzothiazol NLO chromophores were synthesized The fluorine-containing polyimide was synthesized using the monomers 6FHP and 6FDA or PMDA.. The novel hybrid materials were obtained with different inorganic contents and high thermal stability by sol-gel technique. They were characterized by the methods of FT-IR, SEM, TEM, XRD and TGA measuring apparatus to get their surface structure, morphology, particle size, crystal structure and thermal performance. The electro-optical coefficients reached 23pm/V. The film'γ₃₃ still kept 95% of the initial value for 200min, which showed the hybrid materials had application for devices. The order parametersφwere measured through determination of the UV -Vis spectrum before and after polarized film, which showed high-polarized efficiency and good structural design. The second-order nonlinear optical propertiesχ⁽²⁾ of the poled films were stuided according to the one-dimensional rigid oriented gas model. Long-term stability of the dipole alignment was demonstrated for the hybrid. It washown that polymers had good orientational stability.The organic-inorganic hybrids were synthesized containing DR1 NLO chromophore. When PMDA or 6FDA were used, the Tg of the obtained hybrid materials was higher 77,76℃than the corresponding pure polyimide and the electro-optical coefficients reached 28, 29pm/V respectively. Results revealed that T³, Q³ and Q⁴ are the major microstructure forming a network structure from the solid-state ²⁹Si NMR spectra of the hybrid.Novel organic-inorganic hybrids were synthesized containing benzothiazol NLO chromophore. Theheat capacities of FB-2 and PB-2 were carried out with DSC method. The experimental heat capacities were fitted using least square method (range from 273 to 363 K). The fitted equation: FB-2:Cp =1.1552 J K^-1 g^-1 + 4.28×10^<sup>-4 J K-2 g^-1 T– 3.00×104 J K g^-1 T^-2 ;PB-2:Cp =1.1032 J K^-1 g^-1 + 3.79×10^-4 J K-2 g^-1 T– 4.50×104 J K g^-1 T^-2. The Tg of the obtained hybrid materials was higher 120 to 150℃than the corresponding pure polyimide and the electro-optical coefficients reached 27pm/V which showed the hybrid materials had high thermal stability and practical application.The fluorine-containing organic polymer PI^-19 was synthesized with making optical waveguide device and having good thermal stability. It's Tg was 256℃and thermal loss weight(5%) was 380℃. It had two low absorbent windows at optical communication wavelength(1.3 and 1.55μm). It had higher thermal-optical coefficient which could reach ^-4.13 -3.72×10^-4℃^-1(from 650nm to 1310nm).These showed that PI^-19 could be made low loss optical communication device ang optical switch . The conclusion had a little significance to develop new thpe digital optical switch with low driving power.