Advanced Materials Research Vols. 1033-1034

Abstract: Nanofibers composed of the hydrophilic polymer polyvinylpyrrolidone K90 (PVP), cetyltrimethylammonium bromide (CTAB), tetraethyl orthosilicate (TEOS) and Fe₃O₄ were fabricated using an electrospinning process. As a result of the templating and confinement properties of the nanfibers, silica coated magnetite (Fe₃O₄@SiO₂) core-shell nanoparticles (NPs) with high magnetic sensitivity were spontaneously formed through molecular self-assembly when the fibers were added to 80% aqueous ethanol (PH=9.0). The typical saturation magnetization of the Fe₃O₄@SiO₂ composite particles is up to 43.8 emu/g, with superparamagnetic properties being observed at room temperature. Since the nanoparticles have high magnetic sensitivity and are prepared via a facile and convenient strategy, they have much promise in a range of practical applications.

Abstract: In this study, polyacrylonitrile-amidoxime nanofibers were prepared by combining the technique of electrospinning and chemical modification with hydroxylamine chloride. Before modified the Polyacrylonitrile (PAN) nanofibers were bonded with two layers Ethylene-Propylene Side By Side (ES) thermal bonded nonwovens to improve its mechanical strength. Subsequently, they were applied to adsorb copper ions. The results of FT-IR spectra and scanning electron microscope indicated that nitrile groups in PAN were partly converted into amidoxime groups and there were no serious cracks on the surface of PAN-amidoxime nanofibers. The adsorption data of Cu (II) ions was fitted roughly with the Langmuir isotherm. The maximal adsorption capacities of Cu (II) ions reached 176 mg/g.

Abstract: The present study describes degradable and temperature/ionic-strength responsive polyurethane (PU) microspheres fabricated using toluene diisocyanate, polycaprolactone, polyethylene glycol, 2, 2-hydroxymethyl-2-propionic acid and triethylamine for drug delivery.^[1] We studied the properties of Temperature-sensitive, Ionic strength effects on SR, Swelling-deswelling reversibility, In vitro degradation, the result showed that: when the increase in temperature between 20°C and 50°C, as well as the ionic strength at certain temperature tended to decrease SR. The swelling kinetics was also investigated showing the presence of good ability to change reversibly at different temperature. The degradable studies using phosphate buffer solvent revealing polymeric matrix easily be tuned by varying polycaprolactam (PCL) composition, thus matching specific requirements.

Abstract: In polysorbate 80 - alcohol system, Cr₂O₃ powder had been prepared by using chromium-containing waste liquid from 16-dehydropregnenolone acetate. A precipitation was obtained when water was separated from the wastewater. The nanosample was got after the precipitation was calcined at 250 °C and 600 °C. Cr₂O₃ powder structure was characterized by FT-IR, SEM and XRD. The results show that the powders are spherical hexagonal system Cr₂O₃ nanoparticles. The particles size prepared in polysorbate 80 and n-Amyl alcohol system are 50-95 nm. The average value is 78 nm.

Abstract: Carbon nanofiber is a new type of carbon materials and it has wide application prospects. At present, there are many kinds of synthesis methods of carbon nanofibers. Among them, preparation of carbon nanofibers from the controllable flame is a new method. It needs simple laboratory equipments and normal atmosphere pressure in this method. Experimental apparatus is including controllable flame burner, thermocouple, mass flow meter and catalyst preparation system, etc. The key factors of synthesis experiment involving the carbon source, the catalyst and high temperature heat source. Characterization of the carbon nanofibers from the controllable flame is by scanning electron microscope (SEM) and transmission electron microscope (TEM).The experimental results indicated that carbon nanofibers with less impurity can be captured at the temperature from 720 to 880 ̊C when carbon monoxide and iron-based catalyst served as carbon source and the catalyst respectively.

Abstract: The 1, 4-dioxane/ethanol mixed solvent was used as solvent system, and the gel extraction phase separation method was adopted to prepare porous PLLA nanofibrous scaffolds. At that, we studied the effect of using different gel temperature to influence nanofibrous PLLA scaffolds’ structure and performance. The results showed that the morphology of nanofibers and the diameter of fibers could be regulated by gel temperature; a lower gel temperature resulted in higher crystallinity of PLLA scaffold. In addition, the PLLA scaffolds have excellent interconnected network when the gel temperature was in the range of-20 to-10°C. The PLLA scaffolds will become a material to repair the bone tissue, hopefully.

Abstract: ZnO nanofibers on Si (100) were synthesized by electrospun and calcination process. The morphology, structure and optical performance were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence (PL) spectrum. XRD results indicated ZnO nanofibers on Si (100) wafer calcined at 600 °C had a preferred growth orientation of (002) direction. ZnO nanofibers calcinated at 600 °C had an excellent crystalline structure with the diameters ranging from 70 to 150 nm. Defect states in the ZnO nanofibers were observed, which resulted in the green emission in PL spectrum.

Abstract: niobium silicate glass with the mass composition of 35SiO₂-25Nb₂O₅-20Na₂O-10K₂O- 7B₂O₃-3Eu₂O₃ was synthesized by a traditional glass melting method. Glass ceramics containing Na₂Nb₈O₂₁ nanocrystals were prepared by heat treating the glass samples. The results of X-ray diffraction (XRD) indicated that the crystallite in the glass ceramics is Na₂Nb₈O₂₁ nanocrystals. The luminescence spectra showed the emission intensity of Eu³⁺ doped glass ceramics was stronger than that of the glass matrix, and increased with the heat treatment temperature increasing..The transmittance of the glass ceramics can be up to 80% in the near-infrared light area.

Abstract: 1-(2,5-Dimethylthien-3-yl)-2-(4-acetyl-2,5-dimethylthien-3-yl) cyclopentene has been synthesized by a six-step procedure, such as Vilsmeier reaction, Wolff-Kishner-Huang reduction reaction, The Friedel-Crafts acylation, McMurry reaction etc. Upon alternate irradiation with 297 and 500 nm light upon 1-(2,5-Dimethylthien-3-yl)-2-(4-acetyl-2,5-dimethylthien-3-yl) cyclopentene, the absorption spectrum changes reversibly and a clear isosbestic point appears. These results suggest that the compound can undergo photochromism and do not decompose during the irradiation.

Abstract: Asymmetric 2-p-nitrophenyl-5-naphthylmethylene-1,3,4-oxadiazole and 2-p-aminophenyl-5-naphthylmethylene-1,3,4-oxadiazole were synthesized and characterized by IR、¹HNMR and MS analysis, and their optical properties were detected using UV-vis absorption spectroscopy and fluorescence spectroscopy. The existence of electron-withdrawing oxadiazole units causes a significant bathochromic shift of the UV absorption maximum. The largest UV-absorption peak of target compounds is in the range of 298-317 nm, and a new emission band at 402 nm is formed. The fluorescence intensity is gradually enhanced, which strengthens the intramolecular charge transfer effect between the electron-withdrawing oxadiazole and electron-donating aniline.