Advanced Materials Research Vols. 463-464

Abstract: In this study, poly (lactic acid) (PLA)-TiO₂ nano particle nano composites were prepared and the severe aggregation of TiO₂ nano particles in polymer matrixwere reduced by themodification of TiO₂ surface with propionic acid and n-hexylamine. The resulting products were characterized by FT-IR, DSCand SEMtechniques so as to have a better understanding of bondingbetween the polymer and nano particles. All of nano composites with a wide range of TiO₂ additionexhibit the high transparency. SEM micrographs of the nano composites showed of the TiO₂ nano particles were uniformly dispersed in polymer matrices. Photodegradation of PLA-TiO₂ nano particle nano composites were also investigated. The results indicated that nano composites could be efficiently photodegraded by UV irradiation in comparison with pure PLA.

Abstract: The hypervalent organoiodine oxidant PDAIS( poly[4-diacetoxyiodo]styrene ) was prepared via the iodation and acetylation of polystyrene resin by microwave. Polystyrene was iodated with iodine/ iodine pentoxide in solvents such as nitrobenzene and tetrachloromethane, heating in microwave reactor could finish about 20min. The iodometery of loading capacity (ILC) of was up to 2.7mmol/g

Abstract: The synthesis of polystyrene/GO (PS-GO) nanocomposites using the reversible addition-fragmentation chain transfer (RAFT) mediated polymerization method is described. The GO was synthesized and immobilized with a RAFT agent to afford RAFT-functionalized GO nanosheets. The RAFT-immobilized GO was used for the synthesis of PS nanocomposites in a controlled manner using miniemulsion polymerization. The moelcular weight and dispersity of the PS in the nanocomposites depended on the amount of RAFT-grafted GO in the system, in accordance with the features of the RAFT-mediated polymerization. X-ray diffraction and transmission electron microscopy analyses revealed that the nanocomposites had exfoliated morphology, even at relatively high GO content. The thermal stability and mechanical properties of the PS-GO nanocomposites were better than those of the neat PS polymer. Furthermore, the mechanical properties of the nanocomposites were dependent on the RAFT grafted GO content.

Abstract: A well-organized composite of graphene nanosheets decorated with FeC₂O₄ particles was synthesized through a simple chemical precipitation method. The FeC₂O₄ nanoparticles obtained were 100-150 nm in size and homogeneously anchored on graphene sheets as spacers to keep the neighboring sheets separated. The FeC₂O₄-graphene exhbited excellent performances in absorption propties and supercapacitor make potential uses as environment and energy storage materials in future.

Abstract: N-substituted 3,4-fullero pyrrolidine was synthesized according to 1,3-Dipolar cycloaddition of the azomethine ylide. Aspartic acid and glutamic acid with protected α-amino and α-carboxyl groups were reacted with the activated hydroxyl group of N-substituted 3,4-fullero pyrrolidine, respectively. The products were deprotected, affording two novel fullerene α-amino acids, fullerene aspartic acid and fullerene glutamic acid. Their chemical structures were characterized by MALAI-TOF-MS, UV-Vis, FT-IR and 1HNMR. Both fullerene amino acids with a free amino group and a free carboxyl group would have unique property and potential use in medicine and biology. A novel method has been developed to synthesize fullerene conjugate. Their unique chemical structures make them very interesting for their potential use in medicine and biology.

Abstract: Core-shell structured hydroxyapatite (HA)/meso-silica was prepared and used as absorbance of methylene blue (MB). HA/meso-silica was synthesized in three steps: preparation of nano-sized HA by wet precipitation method, coating of dense silica and deposition of meso-silica shell on HA. As-received samples were characterized by Fourier transformed infare spectra, small angle X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. A wormhole framework mesostructure was found for HA/meso-silica. The specific surface area and pore volume were 128 m2•g-1 and 0.36 cm3•g-1, respectively. From the adsorption isotherm, HA/meso-silica with the great specific surface area exhibited a prominent adsorption capacity of MB (134.0 mg/g) in comparison with bare HA (0 mg/g). This study might shed light on surface modification of conventional low-cost adsorbents for removal of organic pollutants from aqueous solutions.

Abstract: Mesoporous ZnO/SnO2 (Zn : Sn = 2 : 1) composite nanofibers with diameter of 49±6 nm and pore size of 6.7 nm were fabricated via the electrospinning technique. Their structure and morphology were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS) and nitrogen absorption-desorption isotherm analysis. The photocatalytic degradation rate of RhB dye by the mesoporous ZnO/SnO2 composite nanofibers was 0.051 min-1, which was more than two times and seven times of that by the pure ZnO (0.024 min-1) and pure SnO2 (0.007 min-1) nanofibers, respectively. The charge separation of electrons and holes was promoted and the recombination of the hole-electron pairs was reduced because of the coupling effect of ZnO and SnO2 in the grain-like composite nanoparticles, thus the quantum efficiency was increased. A schematic diagram of photocatalytic mechanism of mesoporous ZnO/SnO2 composite nanofibers was presented.

Abstract: Mn₃O₄/Cr₂O₃ composite materials were prepared by a chemical coprecipitation method. The structures were characterized by using SEM and XRD, and the supercapacitive behaviors of these composite materials were investigated with cyclic voltammetry (CV) and charge–discharge tests. Morphology of Mn₃O₄/Cr₂O₃ composite materials showed that the Mn₃O₄/Cr₂O₃ composite materials containning a small amount of Cr₂O₃ has a better dispersion compared with that containning a lage amount of it. Owing to the higher surface area and poor crystallization, the Mn₃O₄/Cr₂O₃ composite materials containning a small amount of Cr₂O₃ show much higher specific capacitance (The highest specific capacitance value of 494 F/g was obtained), and were more promising for applications in supercapacitors.

Abstract: Using general graduated approximation (GGA) of the ab-initio based on density functional theory (DFT), three models of possible double Fe doping GaN and three models of possible N vacancy and double Fe codoping GaN were calculated. The results show that in the three models of double Fe doping GaN, the energies of antiferromagnetism (AFM) are lower than the ones of ferromagnetism (FM), which shows that the ground state of Fe doping GaN will be AFM, this agrees on the conclusion of literature [15]. After adding vacancies 2 and 3 respectively, we found a ferrimagnetic (FIM) ground state. But after adding vacancy 1, the ground state was still AFM.

Abstract: Most applications expose the materials to wide range of temperatures, which may influence on thermal behavior of materials. Thermal degradation of wood polymer composites (WPCs) is a crucial aspect for application and manufacturing process of these products. In this research, wood polymer composites with different nanoclay contents were prepared by melts compounding method. The amount of wood flour and coupling agent were fixed at 40% and 10% wt% (total weight), respectively, and the different levels of nanoclay include 0, 3 and 5% wt% were used in preparing the composites. Thermal properties of nanocomposites were characterized by Differential Scanning Calorimeter (DSC) and thermal gravimetric analysis (TGA). The DSC analyses show that the crystallization temperature (Tc), enthalpy ΔHm, and the degree of crystallinity (Xc) of the nanocomposites were increased by addition of nanoclay. The TGA results indicate that by increasing the nanoclay percentage the degradation temperatures and thermal stability was enhanced.