The hollow silica was fabricated by using monodispersed polystyrene microspheres as core template and tetraethyl orthosilicate as silica source, and polyimide nanocomposite films with different hollow silica concentration were successfully prepared via in situ polymerization. The hollow silica and nanocomposite films were characterized. The results indicated that the diameter of the hollow silica is around 30nm and the dielectric constant of the nanocomposite films enhance with the increase of the concentration of the hollow silica.
Polyimide (PI)-matrix composite films containing inorganic nanoparticles (nano-Al2O3 and nano-TiO2) have been fabricated. A proposed model is used to explain different structures of the (Al2O3–TiO2)/PI (ATP) films synthesized by employing in situ polymerization. Dependences of dielectric permittivities of the ATP films on frequency and temperature were studied. Results show the breakdown strength of the films decreases with prolonging the corona aging time. The incorporation of the nano-Al2O3 and nano-TiO2 particles significantly improves the corona resistance of the films. The corona aging also influences the infrared absorbance, the glass transition temperature (Tg), and loss factor (tanδ) of the ATP films.
PI composite films with electrospun BT fibers were fabricated using the in situ dispersion polymerization method. The microstructures, thermal and dielectric properties of the BT fibers and composite films were investigated.
Poly(fluorene-alt-benzothiadiazole) (PFBT) is a promising chiral polymer for use in metamaterials and other photonic applications, due to its large chiral optical activity at visible wavelengths. However, its usages are very limited, since it is not readily patternable into microstructures and challenging to apply to applications. In this paper, we demonstrate photo patterning of chiral PFBT/Achiral SU-8 photoresist to produce high quality structures while retaining the extraordinary chiral optical activity of our previously-reported PFBT/SU8 nanocomposite films. The ability to produce cleanly patterned microfeatures with high chirality may enable wider use of PFBT in chiral metamaterials and other photonic applications.
Abstract Polyimide/polyaniline nanofiber composites were prepared by in situ polymerization with various weight percentages of polyaniline (PANI) nanofibers. X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR), proved the successful preparation of PANI nanofiber composite films. In addition, thermal stability of PI/PANI nanofiber composites was superior relative to PI, having 10 % gravimetric loss in the range of 623 °C to 671 °C and glass transition temperature of 289 °C to 297 °C. Furthermore, the values of the loss tangent tanδ and AC conductivity σAC of the nanocomposite films were notably higher than those of pure polyimide. The addition of 5 wt.% to 15 wt.% PANI nanofiber filler enhanced the activation energy of PI composites from 0.37 eV to 0.34 eV.
<p>A series of nanocomposites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt%, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nanocomposite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane (APB) and 3،3΄،4،4΄-benzophenone tetra carboxylic dianhydride (BTDA) in N,N-dimethylacetamide (DMAc). The resulting nanocomposite films were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA).</p>
Composite films with an ultralow filler content of 0.1 vol% Ag-NDs exhibit an excellent high-temperature discharge energy density of 2.56 J cm−3, together with efficiency exceeding 80% at a temperature of 150 °C.
In Situ Polymerization of Chiral Poly(fluorene-alt-benzothiadiazole) Nanocomposites with Enhanced Chirality