Advanced Materials Research Vols. 634-638

Abstract: EuF₃ nanorods with 400 nm in average diameter and 950 nm in length have been synthesized via a hydrothermal method at low temperature. The phase and shape of the products were characterized by XRD, SEM, HRTEM and SAED. Studies show that the chelating agent EDTA is vital to the morphology of the final product. Under longer UV excitation, the as-prepared EuF₃ nanorods emitted the yellow and red light. This method will find its applications in exploring the crystal growth process and provide guidance for the morphology controllable synthesis.

Abstract: 3D flower-like bismuth trisulphide microcrystallines has been successfully prepared via one step hydrothermal process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser Raman spectrometer techniques. The morphologies of the Bi2S3 microcrystallines were influenced by the surfactant Na2(EDTA), which acts as a structure directing agent.

Abstract: Nanocrystalline TiO2 powder materials is a good use of the performance of paint additives , nano-TiO2 bactericidal coating made its added a new type of green paint , and has been applied in China's architectural coating industry and has achieved a good technical and economic effect.This article discusses some technical characteristics and production application prospects of nanoscale TiO2 powder.

Abstract: The current research is aimed at obtaining suitable nanocomposites for bipolar plate application in fuel cell, which fulfill the requirement for electrical and mechanical properties and low production cost. For this purpose, copper nanoparticles (Cu-NPs) were embedded in polypropylene matrix through wet-chemistry technique with the presence of polypropylene-grafted maleic anhydride as the coupling agent. The resulting nanocomposites were characterized with UV-Vis spectroscopy, TEM, SEM, TGA and electrical conductivity measurement. It was found that the addition of Cu-NPs up to 1.50 wt% has improved effect on the electrical conductivity up to 14.43 S/cm. However, further increase of Cu-NPs loading to 2.00 wt% adversely reduced the electrical conductivity down to 9.31 S/cm, as a consequence of severe agglomeration and large pores formation.

Abstract: CuS nanochains were prepared via a simple hydrothermal reaction at 140 °C for 12 h, employing Cu(Ac)2•H2O and Thiourea as reactants in the absence of any structure-directing agent. The size and morphology of CuS nanochains were characterized by means of X-ray diffraction (XRD) and Transmission electron microscope (TEM); the optical properties of CuS nanochains were investigated by UV–vis absorption spectrum and Fourier transform infrared (FT-IR) measurements. CuS nanochains were found to be constructed by covellite CuS with a hexagonal phase and composed of nanorods with 40-100 nm length and 25 nm Width. The UV–vis absorption of CuS was observed an increased absorption from 300nm to 650 nm and the band gap of CuS nanochains was 1.91 eV.

Abstract: Non-crosslinked and monodisperse polystyrene (PS) microspheres showing uniform size were synthesized by using a dispersion polymerization technique in the presence of the Fenton reagent (FeSO₄/H₂O₂) as an initiator. The effects of stabilizer dosage, monomer concentration, volume ratio of dispersion medium and reaction time on both the morphology and dispersity of PS microspheres were investigated. The results of transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) indicated that the obtained PS microspheres are perfect with uniform size of about 170 nm under the optimum experimental condition. On the basis of the experimental results, the mechanism of PS polymerization was proposed, which should be helpful to guide the preparation of polymer microspheres with desired uniform size. In comparison with the conventional emulsion polymerization, this new synthesis technique with the Fenton reagent exhibits some advantages such as being a simple and fast polymerization process without deoxygenation.

Abstract: The effect of the pH of the preparing solution on the size and shape of gold nanoparticles was studied in the solution containing soybean peptides or β-cyclodextrin (β-CD) as reducing agent. The resulting gold nanostructures were characterized by transmission electron microscopy (TEM), XRD and UV-vis spectra. Different shape of gold nanoparticles such as nanoplates, networked nanowires and spheres were prepared by changing the pH of solution. Electron diffraction pattern showed that the shape changes from plate or network to sphere as the pH of solution is increasing.

Abstract: Chitin nanofibers were prepared from commercially available dried chitin powders by different simple mechanical methods under acid conditions after removal of minerals and proteins. The fibrillated chitin samples were observed by FE-SEM and there was a fine network structure formed by chitin nanofibes with a width of approximately 10-50 nm and high aspect ratio. The mechanical treatment under acid conditions was crucial to facilitate the fibrillation of chitin fibers into nanofibers. The high pressure homogenization in combination with grinding was used to obtain the most transparent chitin nanofibers sheet with a transmittance of 88.5% and tensile strength of 82.34MPa, and the sheet even had a Young’s modulus of 6.17GPa. Thus, chitin nanofibers provide excellent potential as reinforcement of transparent flexible composites to improve the properties of nanocomposites.

Abstract: A novel method is proposed to modify montmorillonite with coupling agents and Hexadecyl triphenyl phosphonium bromide surfactants made by our group (named P-surfactant in the following). The structure of organophilic montmorillonite (OMMT) was investigated by FT-IR, XRD and TG. The FT-IR shows the coupling agents were inserted between the layers of MMT and reacted with –OH of MMT. The results of X-ray diffraction shows that the coupling agents were all intercalated into the layers of MMT. The interlayer spacing of montmorillonite increases to 4.00 nm, the effect of modification is well. The results of TG showed the thermal stability was better.

Abstract: We have successfully prepared monodispersed core-shell microspheres with polystyrene cores and poly(N-isopropylacrylamide) shells by changing solvent from nonpolar to polar for the first time. Effects of stirring time and reaction temperature on the particle size, monodispersity of the microspheres were investigated. With increasing stirring time at 800 rpm, the size of the spheres and the monodispersity are the best when stirring time is 60 min. And with increasing reaction temperature (above phase transition), the size of the microspheres decreases and the monodispersity becomes better.