Advanced Materials Research Vol. 684

Abstract: Nanosized pseudoboehmite particles were synthesized by the precipitation of sodium sulfate and ammonia in aqueous solution at 70°C. After calcinations, the pseudoboehmite could successfully transfer to γ-Al2O3 nanoparticles while retaining their previous morphology. The influence of the reaction conditions on formation of pseudoboehmite and γ-Al2O3 had been researched in detail. The X-ray diffraction analysis showed that nanosized crystalline pseudoboehmite was formed at pH 8-8.5 after ageing 2 hours. Utilization of surfactant(PEG1000) would produce finer nanoparticles with well-dispersion. With the ageing time or the surfactant amount increasing, the morphology of the resulting particles transformed from spherical to fibrous

Abstract: To review the progress on chitosan nanoparticles as drug delivery carriers, the application of chitosan nanoparticles in the fields of organ targeting, DNA transfection, and non-injection administration are summarized according to recent references. The results showed that chitosan nanoparticles as a new drug carrier have important value of research and extensively development prospect.

Abstract: Folic acid-chitosan (FA-CTS) and 10-hydroxycamptothecin (HCPT)-loaded folate-conjugated chitosan (FA-CTS/HCPT) microspheres were prepared by the ionic crosslinking method.The morphological characteristics of microspheres were examined using a scanning electron microscope (SEM). The average particle size and size distribution were determined by dynamic light scattering. The drug encapsulation efficiency (EE) , loading capacity (LC)and release characteristics in vitro were determined using ultraviolet spectrophotometer.The results shown that the microspheres are uniform spherical and regular with a size between 19.79 and81.40μm.Optimized preparation parameters lead to the successful preparation of hydroxycamptothecin-loaded folate-conjugated chitosan microspheres characterized with encapsulation efficiency and loading capacity up to (86.8±0.1)% and 20.6±0.3 % respectively. More then 90% of 10-hydroxycamptothecin was released from microspheres in 4 h at artificial gastric juice, 8h at artificial small intestinal fluid with a good delayed release effect.

Abstract: The present work studies the structural and textural evolution of sol-gel derived carbon nanotube(CNT)/silica composites during the process of thermal treatment. The composites were prepared by sol-gel technique, and their structural and textural changes were traced by scanning electron microscopy, Raman spectra, infrared spectra, and thermogravimetric analysis. The results show that doped CNTs have an impact on the structural and textural evolution of CNT/silica composites during the process of thermal treatment and the CNT/silica composites exhibit good thermal stability during the heat treatment process. However, the composites are not densified even after treatment at 1000°C, quite different from the thermal behaviors of pure silica xerogel, due to the existing of guest CNTs.

Abstract: TiO₂-SiO₂ thin film system is known to be very attractive to use for photocatalytic and display applications. In this study, TiO₂-SiO₂ nano-composite solutions were prepared by adding colloidal solutions consisted of different SiO₂ nano-particle sizes (7-50 nm) into TiO₂ powder-dispersed solutions. TiO₂-SiO₂ thin films on glass substrates were fabricated by the dip-coating technique and their crystal structure, surface morphology and photocatalytic properties were investigated as a function of SiO₂ particle size. While the SiO₂ particle size had little influence on the crystal structure of thin films, the photocatalytic activity and anti-reflectance (anti-glare) characteristics were found to be dependent on the SiO₂ particle size. This result could be explained in terms of surface characteristics and the order of degradation of methylene blue under UV light irradiation.

Abstract: Thermoplastic starch, polylactic acid glycerol and maleic anhydride (MA) were compounded with natural montmorillonite (MMT) through a twin screw extruder to investigate the effects of different loading of MMT on tensile properties and thermal behavior of the nanocomposites. Tensile results showed an increased in modulus, tensile strength and elongation at break. However, beyond 3phr of MMT the modulus of samples decreased because the MMT particles agglomerated. The thermal properties were characterized by using differential scanning calorimeter (DSC). The results showed that MMT increased melting temperature and crystallization temperature of matrix but reduction in glass transition temperature was observed.

Abstract: This study was to investigate the properties of the sulfonated poly(ether ether ketone) (SPEEK) nanocomposite membranes filled with Cloisite 15A® clay, in the presence of 2,4,6 triaminopyrimidine (TAP) as a compatibilizer. The membranes were prepared via solution intercalation method, before they were subjected to performance tests in the temperature range of 27 to 80 oC for comparison with Nafion® 117. The SPEEK membranes were then utilized to measure the open circuit voltage (OCV) and power density for direct methanol fuel cell (DMFC) applications in the temperature range of 27 to 60 oC. The best data obtained, among all the tested membranes, were methanol permeability of 0.52 ×10-6 cm2s-1 and proton conductivity of 47 mScm-1 with the methanol selectivity of 9.1 × 104 S.s.cm-3, even at a high temperature of 60oC.

Abstract: Sb-doped SnO2 (ATO) films were successfully prepared by the spray-pyrolysis method with SnCl2•2H2O and SbCl3 as precursors. The structural, surface morphological, electrical and optical properties of the films were studied in details. The results indicated that all films consisted of tetragonal cassiterite SnO2 with preferred orientation along (110) and (200) crystal plane. A minimum resistivity as low as 1.59×10-3 Ω∙cm has been achieved. The infrared emissivity of the films on the surface of glass was ca. 0.36, which presents potential application in the low-emission window and building ceramics.

Abstract: Sodium dodecyl sulfate/Pt composites and sodium dodecyl sulfate/Pd composites have been synthesized and used to modify the surface of Nafion membrane. Modified Nafion membranes have been characterized by Fourier transform infrared spectroscopy (FTIR). The properties of the modified membranes, in terms of their conductivity and the performance of the membrane electrode assembly (MEA) in the direct methanol fuel cells (DMFCs), have been analyzed and compared with those of the bare Nafion. It is found that the DMFC performance of the membranes modified by two kinds of catalytic materials are better than that of the bare Nafion when operated with 2.0 M methanol. The good conductivity and high cell performance makes the modified Nafion interesting candidates for DMFCs applications.

Abstract: Structure transitions induced by selective solvents in diblock copolymer films are investigated by density functional theory. By changing the selectivity and the packing fraction of selective solvents, the disorder-lamellar transition, the position switched lamellar phase transitions and the reentrant transitions are observed. Phase diagrams are constructed to clarify these effects. The results provide an effective way to control the transitions between the different microstructures.