Hybrid nanocomposite films of silica (SiO2) in polyimide (PI) from 4,40-(hexafluoroisopropylidene) diphthalic arhydride (6FDA), 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FHP) and nonlinear optical (NLO) molecule have been successfully fabricated by an in situ sol-gel process. The silica content in the hybrid films was varied from 0 to 22.5wt%. These nanocomposite films exhibit fair good optical transparency. Fourier transform infrared (FTIR) spectroscopy results confirm the formation of SiO2 particles in PI matrix. Scanning electron microscope (SEM) images show that the SiO2 phase is well dispersed in the polymer matrix. Their glass transition behavior and thermal stability were investigated by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TG).

ABSTRACT: A series of polyimide-based second-order nonlinear optical (NLO) materials were synthesized from poly (hydroxy-imide)s, followed by the Mitsunobu reaction with NLO chromophores. These chromophores, based on a nitro group connected with benzothiazole as the acceptor end of a donor-ð- bridge-acceptor chromophore and a hydroxy-functional amino group as the donor end, have specific chemical stability. The resulting polymers were highly soluble in aprotic polar solvents such as DMF, DMAc, NMP, etc. Molecular structural characterization for these polymers was achieved by 1H NMR, FT-IR, and UV-visible spectroscopes. The glass transition temperature for the resulting NLO polyimides was in the range 197-247℃, and most of them showed high thermal stability. The polymer solutions could be spin coated on the indium-tin-oxide (ITO) glass or other substrates to form optical quality thin films. The electrooptic coefficients (γ33) at the wavelength of 830nm for polymer thin films poled around the optimal temperature (Topt) were in the range of 9-32pm/V, and the value remained well at elevated temperatures for move than 120h in the air. The NLO stability of these polyimides was also studied by studying the UV-visible spectra of their poled films.

Collgen-g-PMMA copolymer and indium oxide nanoparticles were prepared by grafting copolymerization of methyl methacrylate onto collagen and sol-gel process separately, and collagen-g-PMMA/indium oxide nanocomposite was prepared by ultrasonic wave irradiation. Simultaneously two collagen/indium oxide nanocomposites were prepared by liquid-liquid dispersion and ultrasonic wave irradiation respectively in the interest of infrared emissivity investigation (8-14Am). Three nanocomposites were characterized by SEM, TEM, IR spectroscopy, thermogravimetric analysis and infrared emissometer. SEM and TEM indicated that three nanocomposites were of different microstructures, and that collagen-g-PMMA copolymer and indium oxide nanoparticles self-assembled into homogeneously spherical aggregates of 600nm in diameter, which is owing to, we proposed, the high activity of amphiphilic collagen-g-PMMA copolymer nanoparticles. It was found that two nanocomposites showed significantly lower infrared emissivity value than their components, but the rest one did not. Decrease mechanism of infrared emissivity value of nanocomposite was discussed based on microstructure. It was assumed that the decrease in infrared emissivity value of collagen-g-PMMA/indium oxide nanocomposite was attributed to strong interfacial interactions between collagen-g-PMMA and indium oxide.