Advanced Materials Research Vols. 399-401

Abstract: Hydrophilic CdTe and NIR CdHgTe QDs were successfully transferred from aqueous solution to nonpolar chloroform solvent via efficient phase transfer reagent to synthesize lipid-QDs. The liposomes showed bright fluorescence under the fluorescence microscope. It was confirmed that fluorescence resonance energy transfer (FRET) occurred between two types of QDs encapsulated in lipid bilayer with an excitation wavelength of 370nm, and the FRET efficiencies were satisfied (quenching efficiency was 51% and enhance efficiency was 40%), which laid a foundation for the research of drug release from liposomes.

Abstract: With the development of science and technology, ordered microstructures with special functions have aroused intense research interest .It has been widely used in many fields. This paper summaries the research status in application of the orderly function structure and looks into its future development.

Abstract: Electrochemical corrosion behavior of Cu-20Fe-12Cr alloys prepared by powder metallurgy (PM) and mechanical alloy (MA) with the different grain size was studied in solutions containing chloride ions. The free corrosion potentials move toward negative values and corrosion rates become faster with the increase of chloride ion concentrations for two alloys. Electrochemical impedance spectroscopy (EIS) plots of PMCu-20Fe-12Cr alloy are composed of a capacitive loop and a diffusion tail. Corrosion processes are controlled by diffusion. EIS plots of MACu-20Fe-12Cr alloy in Na2SO4 or 0.02mol.L^-1NaCl solution are unable to have characteristics of Warburg impedance. Corrosion processes are controlled by electrochemical reactions. After chloride ion concentrations increase up to 0.05mol.L^-1, their EIS plots are composed of double capacitive loops with a straight line induced Warburg resistance between two capacitive loops. The above EIS plots imply the existence of pitting corrosion. The corrosion rates of MACu-20Fe-12Cr alloy become faster than those of PMCu-20Fe-12Cr alloy because the reduction in the grain size of MACu-20Fe-12Cr alloy produces large concentrations of grain boundaries.

Abstract: Carbonaceous polysaccharide microsphere with strong adsorption ability has been successfully synthesized under hydrothermal conditions, using glucose as the carbon source. The carbon microsphere (CMS) proved to be an effective adsorbent for the removal of formaldehyde. The obtained TiO₂/C nanocomposite proved to be more favorable in degrading organic pollutants than that of naked TiO₂. The research is expected to be useful in industrial application for the indoor air purification and removing of trace organic pollutants in water.

Abstract: Quantum-sized TiO₂ had been prepared by using Ti(n-OC₄H₉)₄ as the raw material via a microwave-assisted sol-gel method. The influence of different processing temperature and time on the size of TiO₂ was researched. The TiO₂ was characterized by transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). The prepared TiO2 presents anatase phase structure by TEM and XRD. The photocatalytic activity of TiO₂ was evaluated by the degradation rate of methyl orange in aqueous solution. The particle size of TiO₂ was about 9.10 nm when the processing temperature was 160°C and the processing time was 90 min (160°C-90min), and the photocatalytic performance was the best under this size. When the initial concentration of methyl orange was 10 mg/L and the amount of quantum-sized TiO₂ was 0.6 g/L, the degradation rate of methyl orange under ultraviolet and solar irradiation at room temperature in 60 min were 40% and 86%, respectively.

Abstract: The main objective of this work was to prepare high purity α-alumina powder (α-Al₂O₃) by mixed oil-in-water microemulsion route. In this study α-alumina was prepared by quaternary microemulsion system (water/surfactant/co-surfactant/oil-phase). OP-10, alcohol and the mixed solution of cyclohexane and aluminium isopropoxide were used as surfactant, co-surfactant and oil-phase, respectively. After drying the amorphous precursor powder, α-alumina powder is obtained by sintering at 1200°C for 3-5h. The X-ray diffraction pattern shows the presence of alumina phase with crystal structure and the slow scan with step size 0.0170°/sec of selected diffraction peaks such as (113) has been recorded and calculated by Scherer’s formula. The average crystallite size is about 40nm.

Abstract: Poly(butyl methacrylate) (PBMA) colloidal crystal templates were assembled orderly on the clean substrates of monocrystalline silicon by dip-drawing technique and titanium dioxide (TiO₂) macroporous membranes were prepared by using sol-dipping template method to fill the interstices among the PBMA templates, followed by calcination to remove the templates at 550°C. Calcination of the PBMA templates was carried out according to the following procedure: the rate of rising temperature was 5°C/min from room temperature to 150°C, 2°C/min from 150°C to 270°C, 1°C/min from 270°C to 430°C, 2°C/min from 430°C to 550°C and maintained it at 550°C for 2h. X-ray diffraction (XRD) spectra indicated the macroporous materials were anatase structure. The polymerization mechanism of BMA with Fenton reagent as a new initiator was discussed, and the removal process of the PBMA templates and the formation of TiO₂ pore size were investigated, respectively. The results showed that the new method of polymerization overcomes many problems associated with the conventional emulsion polymerization techniques such as long reaction time, necessary deoxygenation, and complicated operation.

Abstract: Crude vermiculite is used as raw materials, heat-treated for activation, leached with a complexing acid, exchanged with sodium solution, following contacted with polyhydroxyl aluminium solution. The Al-intercalated vermiculites are prepared by ion exchange. The phase and microstructure of the composite material are analyzed by means of XRD, TEM, TG-DSC, et al. The results reveal that the basal spacing of vermiculite expanded by intercalation of Al-species, and the interlayer of vermiculite inlaid with a large amount of nanometer Al-species particles.

Abstract: Nanocomposite microspheres were successfully prepared by grafting TiO₂ particles to microPCMs by chemical reaction method. The effects of modification of nano TiO₂ particles, adding time of TiO₂ dispersion and the amount of TiO₂ on the surface morphology were investigated. The results indicated that the optional method is adding the TiO₂ dispersion as soon as all the prepolymer was added to the reaction system, and the optional mass ratio of TiO₂ to microPCMS is 10wt%.

Abstract: A type of calcium borate whiskers with highly thermal stability was synthesized by hydrothermal method at 180 °C for 2 h, using borax, calcium chloride and sodium hydroxide as raw reactants. The X-ray powder diffraction (XRD) indicated that as-prepared products were composed of monoclinic Ca₂B₂O₅·H₂O phase. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed calcium borate whiskers with a length of 50~100 μm and diameter 1.0 ~3.0 μm. Selected-area electron diffraction (SAED) pattern showed that the calcium borate whiskers were single crystalline structure. The adjustment of temperature of hydrothermal reaction, can lead to obvious morphology changes of products, and the possible chemical reaction and growth mechanism were proposed. Furthermore, the analysis of thermogravimetry (TG) showed the calcium borate whiskers released crystal water at 370~425 °C.