ABSTRACT
A novel method that selectively polymerizes pyrrole on the silica surface without inducing polymerization in bulk solution is developed, which is based on in situ generation of the NO(+) ion as an oxidant at the silica surface.
ABSTRACT
Ordered nanoporous silica (MSU-H) with high surface area has been utilized as a solid substrate of a surface-modified hybrid sorbent for the application to the removal of U(VI). Carboxymethylated polyethyleneimine (CMPEI) with a strong complexing property has been introduced to the pore surface of MSU-H substrate. CMPEI-modified MSU-H (CMPEI/MSU-H) has been characterized by scanning electron microscopy and nitrogen sorption. In a kinetic experiment for 12.5 ppm U(VI) solution at pH 4.0, 99% U(VI) was removed from solution by the hybrid sorbent within less than 10 min, indicating that the sorption of U(VI) on the CMPEI/MSU-H proceeds very rapidly. It was evident that a U(VI) sorption capacity increased with pH in the range of 2.0 to 4.0. The CMPEI/MSU-H showed a high sorption capacity of 153 mg/g-sorbent at pH 4.0. In particular, the CMPEI/MSU-H showed a significantly high uranium loading stability. Only about 1% U(VI) was released out of CMPEI/MSU-H during 4 months, when the CMPEI/MSU-H was treated with polyacrylic acid.
Subject(s)
Silicon Dioxide/chemistry , Uranium/isolation & purification , Water Purification/methods , Adsorption , Particle Size , Polyethyleneimine/chemistry , Porosity , Pressure , Regression Analysis , Uranium/chemistryABSTRACT
We report the preparation and application of indium tin oxide (ITO) coated fluorine-containing polyimide/organoclay nanocomposite substrate. Fluorine-containing polyimide/organoclay nanocomposite films were prepared through thermal imidization of poly(amic acid)/organoclay mixture films, whilst on which ITO thin films were coated on the films using a radio-frequency planar magnetron sputtering by varying the substrate temperature and the ITO thickness. Finally the ITO coated fluorine-containing polyimide/organoclay nanocomposite substrate was employed to make flexible organic light-emitting devices (OLED). Results showed that the lower sheet resistance was achieved when the substrate temperature was high and the ITO film was thick even though the optical transmittance was slightly lowered as the thickness increased. approximately 10 nm width ITO nanorods were found for all samples but the size of clusters with the nanorods was generally increased with the substrate temperature and the thickness. The flexible OLED made using the present substrate was quite stable even when the device was extremely bended.
ABSTRACT
We prepared transparent polyimide (PI) and organo-modified montmorillonite (OMMT) nanocomposite films from the solution of poly(amic acid) and various amounts (0.5-2 wt%) of OMMT in N,N-dimethylacetamide (DMAc). The Poly(amic acid) was prepared from the reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2'-bis (trifluoromethyl)-4,4'-diamino phenyl (TFDB). Dodecylamine (C12-) and dodecyltriphenylphosphonium chloride (C12PPh-Cl-) were used as organic modifiers in OMMT. The PI/OMMT nanocomposite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis transmission spectra, thermomechanical analysis (TMA), and rheometric dynamic analysis (RDA). As the OMMT contents is increased, PI/OMMT nanocomposites generally show better properties compared to pristine PI films, although the transparency of the PI/OMMT nanocomposite films is sacrificed slightly. However, it is concluded that these nanocomposite films are good candidates for potential flexible substrates.