Volumetric and Isentropic Compressibility Behavior of Ionic Liquid, 1-Propyl-3-Methylimidazolium Bromide in Acetonitrile,Dimethylformamide, and Dimethylsulfoxide at <Emphasis Type="Italic">T</Emphasis> = (288.15 to 308.15) K

Density and speed-of-sound data for 1-propyl-3-methylimidazolium bromide ([C₃mim][Br]) + acetonitrile (MeCN), [C₃mim][Br] + dimethylformamide (DMF), and [C₃mim][Br] + dimethylsulfoxide (DMSO) binary mixtures in the dilute concentration region are reported at T = (288.15 to 308.15) K. From these data, apparent molar volume, isentropic compressibility, excess molar volume, and isentropic compressibility deviation values have been calculated. Negative deviations from the ideal behavior of both molar volume and isentropic compressibility have been observed for all systems investigated in this study. It has been found that deviations from ideal behavior for the [C₃mim][Br] + MeCN system are larger than those for the [C₃mim][Br] + DMF system which, in turn, are larger than those for the [C₃mim][Br] + DMSO system. The results have been interpreted in terms of ion–dipole interactions and structural factors of the ionic liquid and investigated organic solvents.     

Microwave synthesis of SrCO3 one-dimensional nanostructures assembled from nanocrystals using ethylenediamine additive

One-dimensional SrCO₃ nanostructures assembled from nanocrystals have been successfully synthesized by a microwave-assisted aqueous solution method at 90 °C using Sr(NO₃)₂, (NH₄)₂CO₃ and ethylenediamine (C₂H₈N₂). Our experiments show that the microwave heating time plays an important role in the size and morphology of SrCO₃. A rational mechanism based on the oriented attachment self-assembly is proposed for the formation of SrCO₃ nanostructures. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). This method is simple, fast, low-cost and suitable for large-scale production of SrCO₃ nanostructures with different morphologies. We expect that this method may be extended to the preparation of nanostructures of other kinds of carbonates.     

Use of 1-alkyl-3-methylimidazolium l-lactates as both ligand and reaction media for AGET ATRP of acrylonitrile

Chiral ionic liquids, [C₂mim][LLA], [C₄mim][LLA] and [C₆mim][LLA] were firstly applied as both ligand and reaction media for atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) of acrylonitrile (AN) with ascorbic acid (VC) as reducing agent in the presence of air. A small but clear increase of polyacrylonitrile (PAN) isotacticity was observed for AGET ATRP of AN in [C₆mim][LLA] than in [C₆mim][BF₄]. PAN isotacticity markedly increased with the content of [C₆mim][LLA]. Compared with in [C₂mim][LLA] and [C₄mim][LLA], the rate of AGET ATRP of AN in [C₆mim][LLA] was fastest and the polymerization was best controlled. Well-defined PAN with molecular weight at 76,590, relatively narrower distribution at 1.27 and higher isotacticity at 0.37 was successfully prepared in [C₆mim][LLA].     

Water-assisted growth and characterization of SnO2 nanobelts

SnO₂ nanobelts have been synthesized by water-assisted growth at 850 °C using high pure Sn powders as the source materials. The as-synthesized products were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersed X-ray spectroscopy (EDX), infrared spectrum (IR) and room-temperature photoluminescence (PL) spectrum. XRD pattern of the sample is quite in accord with the standard pattern of the tetragonal rutile SnO₂; SEM and TEM images show that the uniform single-crystalline SnO₂ nanobelts are about tens of micrometers in length, 70-100 nm in width and 5-8 nm in thickness, and is smooth in surface. The special IR and PL properties were also detected by IR and PL testing. The growth mechanisms and special properties relative to the SnO₂ nanostructures are discussed.     

Synthesis and characterization of flower-like MoS2 microspheres by a facile hydrothermal route

Flower-like MoS₂ microspheres with high purity were successfully synthesized via a facile hydrothermal route by adding sodium silicate as an additive. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD patterns showed that the MoS₂ microspheres had good crystallinity with well-stacked layered structure. TEM and SEM images showed that the MoS₂ microspheres had uniform sizes with mean diameter about 480 nm and were constructed with MoS₂ sheets with thickness of several nanometers. It was found that the possible precursor H₄SiMo₁₂O₄₀ obtained by sodium silicate reacting with sodium molybdate played a crucial role in the formation of the flower-like MoS₂ microspheres in our experiment. A possible formation mechanism of MoS₂ microspheres was preliminarily presented.     

Microwave-assisted synthesis of hydroxyapatite hollow microspheres in aqueous solution

We report a template-free microwave-assisted hydrothermal method for the preparation of hydroxyapatite hollow microspheres constructed by the self-assembly of nanosheets using Ca(CH₃COO)₂, Na₂HPO₄, NaH₂PO₄ and sodium citrate in aqueous solution. X-ray powder diffraction (XRD) patterns indicated that the as-prepared samples consisted of hydroxyapatite. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) micrographs showed that the as-prepared products were composed of hollow microspheres assembled with nanosheets and had three-dimensional nanoporous nanostructured networks. The experimental parameters were varied to investigate their effects on the product, and a possible formation mechanism was proposed. The as-prepared hydroxyapatite hollow microspheres have a potential application in drug delivery.     

Boehmite nanopetals self assembled to form rosette-like nanostructures

Rosette-like boehmite nanostructures were prepared successfully via a simple hydrothermal process. The obtained material was characterized with X-ray powder diffractometry (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Using Scherrer formula, the average crystallite size of the obtained boehmite rosettes was measured to be about 8 nm. It was shown that boehmite nanopetals with average width of about 41 nm determined by TEM, were formed during the hydrothermal process and then self assembled due to weak hydrogen bonds to fabricate boehmite rosettes. The specific surface area of the obtained rosette-like nanostructures was calculated through BET N₂-adsorption technique to be about 143.08 m²/g.     

Synthesis and characterization of novel flower-like CeF3 nanostructures via a rapid microwave method

Novel flower-like CeF₃ nanostructures with a mean diameter of 190 nm were successfully synthesized via a rapid and facile microwave irradiation route using ethylenediaminetetraacetic acid disodium as the complexing reagent. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence (PL). XRD patterns showed that the CeF₃ nanoflowers were hexagonal phase and had good crystallinity and purity. TEM and SEM images showed that the as-prepared CeF₃ samples displayed 3D flower-like nanostructures and had uniform sizes and morphologies. The experimental results revealed that the as-prepared CeF₃ nanoflowers might be assembled by nanodisks. The formation process of the CeF₃ nanoflowers was preliminarily investigated.     

Self-assembly into temperature dependent micro-/nano-aggregates of 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin

Various nanostructures of 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin (H₂TCPP) can be easily synthesized by a surfactant-assisted self-assembly (SAS) method at different temperatures. When the DMF solution of porphyrin monomer was injected into cetyltimethylammonium bromide (CTAB) aqueous solution by a syringe, diverse H₂TCPP nanostructures dependent on the different temperatures, including hollow nanospheres, solid nanospheres and nanospheres with holes, were successfully obtained. As a result, the suitable concentration of the CTAB aqueous solution used to form nanostructues of porphyrin ranges from 0.15 to 0.2 mM. The various morphologies of porphyrin nanostructures were characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). UV–vis adsorption spectra showed that the micro-/nano-aggregate properties of porphyrin transformed from H-aggretates to J-aggregates during the process of self-assembly of porphyrin at different temperatures. Fluorescence spectra revealed a greater fluorescence quenching of various micro-/nano-aggregatess of porphyrin formed at different temperatures in aqueous solution, compared to the DMF solution of porphyrin monomer.     

Large-scale synthesis and characterization of fan-shaped rutile TiO2 nanostructures

Large-scale fan-shaped rutile TiO₂ nanostructures have been synthesized by means of a simple hydrothermal method using only TiCl₄ as titanium source and chloroform/water as solvents. The physicochemical features of the fan-shaped TiO₂ nanostructures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), nitrogen absorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) and Fourier transform infrared spectroscopy (FTIR). Structural characterization indicates that the fan-shaped TiO₂ nanostructures are composed of several TiO₂ nanorods with diameters of about 5 nm and lengths of 300-350 nm. The average pore size and BET surface area of the fan-shaped TiO₂ nanostructures are 6.2 nm and 59 m²/g, respectively. Optical adsorption investigation shows that the fan-shaped TiO₂ nanostructures possess optical band gap energy of 3.11 eV.     

Synthesis of doped ZnS one-dimensional nanostructures via chemical vapor deposition

ZnS one-dimensional (1D) nanostructures doped with Mn or Cd have been rapidly synthesized in large scale via a chemical vapor deposition process. Using Zn and S as precursors and MnCl₂ or Cd as doping source, the doped ZnS 1D nanostructures were obtained. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to characterize the as-synthesized ZnS nanostructures. The catalytically grown ZnS 1D nanostructures, including nanowires and nanoribbons, are tens of micrometers in length. All the products are wurtzite ZnS in structure and preferentially grow along the [001] direction. The room temperature photoluminescence properties of these doped ZnS nanostructures are presented.     

Acetylation of β-cyclodextrin in ionic liquid green solvent

The ionic liquid (IL), 1-butyl-3-methylimidzolium bromide ([C₄mim]Br), synthesized under supercritical CO₂, was developed as a green solvent for the dissolution, regeneration and acetylation of β-cyclodextrin (β-CD). The dissolution of β-CD in [C₄mim]Br of 25 wt% could be reached at 25 °C. The acetylation of β-CD was carried out under acetic anhydride in [C₄mim]Br in the absence of catalyst. β-CD acetates with different degrees of substitution of 0.07–1.14 were obtained directly under the homogeneous reaction conditions. The reaction medium of IL applied can be easily recycled and reused after the synthesis of β-CD acetate. The effects of reaction time, temperature, and acetic anhydride/AGU on the acetylation of β-CD were investigated. The acetylated β-CD samples were characterized by NMR, FT-IR, and X-ray diffraction (XRD) spectroscopy. It is the first time that we have demonstrated that ILs can be used as an environmentally friendly solvent for the acetylation of β-CD, which will open a new route to acetylation of β-CD under green solvent without catalyst.     

Synthesis and characterization of anatase and rutile TiO2 nanorods by template-assisted method

Well-aligned anatase and rutile TiO₂ nanorods and nanotubes with a diameter of about 80–130 nm have successfully been fabricated via sol-gel template method. The prepared samples were characterized by using thermogravimetric (TG) and differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The XRD results indicated that the TiO₂ nanorods were crystallized in the anatase and rutile phases, after annealing at 400–800 °C for different periods of time from 0.2 to 10 h.     

Synthesis and photocatalytic properties of TiO2 nanostructures

TiO₂ particles, rods, flowers and sheets were prepared by hydrothermal method via adjusting the temperature, the pressure and the concentration of TiCl₄. The as-prepared TiO₂ powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra and N₂ adsorption–desorption measurements. It was found that pressure is the most important factor influencing the morphology of TiO₂. The photocatalytic activity of the products was evaluated by the photodegradation of aqueous brilliant red X-3B solution under UV light. Among the as-prepared nanostructures, the flower-like TiO₂ exhibited the highest photocatalytic activity.     

The effects of different acids on the preparation of TiO2 nanostructure in liquid media at low temperature

Titania of different crystalline structures and morphology was prepared by the low temperature dissolution–reprecipitation process (LTDRP) of amorphous precursors in various acidic mediums at 70 °C for 8 h. The effects of different acids on the crystalline and morphology of titania nanostructures were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results showed that HCl, HNO₃ and their mixture favored the formation of rod-like rutile TiO₂, while H₂SO₄ and its mixture with HCl or HNO₃ retarded the formation of rutile but favored the formation of the anatase phase of with an irregular shape. The mechanism of the formation of various titania nanostructures was also discussed.     

Hydrothermal synthesis of hollow MoS2 microspheres in ionic liquids/water binary emulsions

Hollow molybdenum disulfide (MoS₂) microspheres were synthesized in ionic liquids (1-butyl-3-methylimidazolium chloride, [BMIM]Cl)/water binary emulsions by the hydrothermal method at 180 °C for 24 h. The optimum value of volumetric proportions (ILs/water) equaled 1:9. The structure and morphology of products were characterized by means of X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The experimental results gave the evidences that the sample is consists of hollow spheres 1.8 - 2.1 μm in diameter, and there are much sheet-like structures on the surface of hollow MoS₂ microspheres. In addition, ILs could be collected and reused for subsequent reactions.     

Synthesis and photo-catalytic degradation property of nanostructured-ZnO with different morphology

ZnO nanostructures with different morphology have been successfully fabricated by a simple relative low temperature approach at 90 °C for 5 h without surfactant assistance. These structures can be easily tailed using varied concentrations of sodium hydroxide (NaOH) and different amounts of the hydrazine hydrate (N₂H₄·H₂O). X-ray diffraction (XRD) result proves the formation of ZnO with wurtzite structure. Microstructure as revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicates that the rod-like and chrysanthemum-like ZnO nanostructures contain many radial nanorods, which grow along the [0001] direction. Furthermore, the as-prepared ZnO nanomaterials exhibit high activity on the photo-catalytic degradation of typical persistent organic pollutants (POPs), indicating that they are promising as semiconductor photo-catalysts.     

Facile tailoring of titanate nanostructures at low alkaline concentration by a solvothermal route

Nanostructured titanates with different morphologies such as nanoflakes, nanotubes, and nanofibers have been selectively synthesized by a simple solvothermal treatment of commercial anatase TiO₂ using the mixed water–ethanol cosolvent at low alkaline concentration. The effects of solvothermal temperature, volume ratio of H₂O to C₂H₅OH, amount of NaOH and solvents on the formation of titanate nanostructures have been systematically studied through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). At low concentration of NaOH solution (the actual concentration of OH⁻ in the solution is only 0.58 M), different titanate nanostructures are achieved by simply changing the volume ratio of H₂O to C₂H₅OH at 180 °C and titanate nanotubes can be synthesized between 100 and 180 °C. A probable formation mechanism is proposed based on XRD, SEM and TEM analysis. The influence of cosolvent on the transformation from anatase TiO₂ to titanate is also investigated.     

Formation of Ag nanoparticles within the thermosensitive hairy hybrid particles

Herein we report on the production of composite core-shell particles, which are actually self-assembly of poly (N-isopropylacrylamide)-based amphiphilic block copolymers as a template for metal-block copolymer nanocomposites formation. Organic-inorganic composites were prepared with Ag nanoparticles embedded within colloidal particles of an amphiphilic, thermally responsive polymer. To promote the incorporation of unaggregated Ag nanoparticles, temperature responsive microspheres of poly (N-isopropylacrylamide) (NIPAM) block with polystyrene were synthesized. Polyethyleneimine (PEI) could act as the linker between Ag ions (Ag nanoparticles) and poly (styrene-b-N-isopropylacrylamide) (PS-b-PNIPAM) colloids and the reducing agent in the formation of Ag nanoparticles. Transmission electron microscopy (TEM) measurements confirmed the nanostructures, ¹HNMR and FTIR characterized the components of the resulting nanoobjects. These stimuli-responsive hybrid microspheres will have potential applications in biomedical areas, such as tissue engineering and drug delivery.     

Three-dimensional (3D) sea-urchin-like hierarchical TiO2 microspheres: growth mechanism and highly enhanced photocatalytic activity

Three-dimensional (3D) sea-urchin-like hierarchical TiO₂ microspheres were synthesized by a template-free hydrothermal method. The effects of preparation parameters on the microstructure of 3D sea-urchin-like hierarchical TiO₂ were investigated using scanning electron microscopy (SEM), transmission electron microscopy, X-ray diffractometer, energy-dispersive X-ray spectrometer and Brunauer–Emmett–Teller technologies. The growth mechanism and photocatalytic activity of 3D sea-urchin-like TiO₂ microspheres were discussed. The results of electron microscopy characterizations SEM showed that the microspheres were consisted of numerous one-dimensional (1D) nanorods. A three-step growth model: oxygenated to be 1D nanorods, self-assembly and protonation, was proposed to illustrate the growth mechanism of sea-urchin-like structures. The synthesized 3D sea-urchin-like hierarchical TiO₂ microspheres exhibited a better photocatalytic activity for photodegradation of rhodamine B under sunlight irradiation compared to that of P25, which was attributed to the special 3D hierarchical nanostructure, the increased number of surface active sites and anatase crystal structure.