Facile fabrication of polymer-inorganic hybrid particles with various morphologies by combination of hydrolytic condensation process with radiation seeded emulsion polymerization

A novel approach was proposed to the synthesis of poly(styrene-divinyl benzene-acrylic acid)/poly [3-(methacryloxy)propyl trimethoxysilane-styrene] [P(St-DVB-AA)/P(MPS-St)] hybrid particles. The morphologies of the particles could be tuned from raspberry-like to snowman-like by simply changing the feeding amount of second monomer or inorganic precursor. The fabricated raspberry-like ones could be modified to obtain hydrophobic surface with a contact angle up to 146°. And the snowman-like ones could be used as solid surfactant to stabilize water/styrene (W/St) mixtures, thus hierarchical porous materials could be obtained after the polymerization of monomer phase. The preliminary application of such soap-free block materials in oil-polluted water treatment was also investigated.

Investigations in annealing effects on structure and properties of β-isotactic polypropylene with X-ray synchrotron experiments

The influence of annealing on the microstructure and mechanical properties of β-form isotactic polypropylene (iPP) was investigated via in situ synchrotron small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Transition of β-iPP to α-iPP was investigated via recrystallization at high annealing temperatures (T _a?>?120 °C). And crystallinity, crystal sizes, and long period of ordered structure increased with increasing annealing temperature. Abrupt changes were found in both mechanical properties and structural features at the same T _a range (～120 °C). The in situ synchrotron SAXS and WAXD shows that the destruction of b phase at yielding and after yielding should account for the ductility of β-iPP. The thermodynamics and kinetics of annealing were investigated with DSC and X-ray synchrotron experiments. A characteristic annealing time was investigated, which measures the rate of phase evolution in annealing of β-iPP. Eventually, a hypothesized model can be used to describe the property/structure relations during this process.     

Dielectric relaxation behavior of ternary systems of water/toluene/Triton X-100: the effects of water and oil contents on microemulsion structure

Dielectric relaxation studies were conducted on the ternary systems of the nonionic surfactant Triton X-100 (a nonionic surfactant with a polyoxyethylene chain)/toluene/water in the frequency range from 40 Hz to 110 MHz. The contents of water and toluene were varied separately while the ratios of the other two components were fixed. Remarkable dielectric relaxations were observed around 1 MHz and dielectric intensity shows different variation with the increase of the contents of water or toluene. Dielectric parameters were obtained by fitting the data using the Cole–Cole equation with one dispersion term. The reverse micelles, water-in-oil, and oil-in-water micro-regions of the microemulsions were identified by the dependence of conductivity of the dispersed phase and continuous phase on the contents of water or toluene. Hanai theory and the corresponding analysis method were used to calculate the phase parameters of the constituent phases. The analysis results suggest that the dielectric relaxation probably arises from the interfacial polarization.     

Enzymatic Synthesis of γ-Glutamylmethylamide from Glutamic Acid γ-Methyl Ester and Methylamine Catalyzed by Escherichia coli Having γ-Glutamyltranspeptidase Activity

A new method for the synthesis of γ-glutamylmethylamide is presented. Glutamic acid γ-methyl ester was used as substrate for γ-glutamylmethylamide synthesis catalyzed by Escherichia coli with γ-glutamyltranspeptidase activity. Reaction conditions were optimized by using 300 mM glutamic acid γ-methyl ester and 3,000 mM methylamine at pH 10 and 40 °C. Bioconversion rate of γ-glutamylmethylamide reached 87 % after 10 h. γ-Glutamyltranspeptidase was reversibly inhibited only when glutamic acid γ-methyl ester was above 300 mM.     

双核铜配合物Cu2(2,2′-bpy)2(2-bba)4的合成、表征与晶体结构

在室温下,以2-溴苯甲酸和2,2'-联吡啶为配体,通过溶液法在甲醇/水的混合溶剂中反应合成了双核铜(II)配合物Cu2(2,2'-bpy)2(2-bba)4。通过元素分析、红外光谱、热重测试技术和X射线粉末衍射对其进行了结构表征,同时用X射线单晶衍射分析确定了其晶体结构。结果表明,其晶体属正交晶系,空间群为Pbca,晶胞参数:a=20.619(4),b=10.098(2),c=21.865(4),V=4552.5(15)3,Dc=1.808g·cm-3,μ=4.505mm-1,F(000)=2440.0,Z=4,最终残差因子R1=0.0583,wR2=0.1200。配合物为双核结构,每个结构单元中2个Cu(II)离子通过2个2-溴苯甲酸根配体单齿桥联。配合物中的每个Cu(II)离子为五配位的结构,分别和来自2个单齿桥联的2-溴苯甲酸根的2个氧原子、1个单齿配位的2-溴苯甲酸根的1个氧原子及来自1个2,2'-联吡啶的2个氮原子配位形成了畸变的四方锥型结构,分子间则通过弱的C—H…O氢键作用形成了一维链状的结构。CCDC:972827。     

Alumina nanofibers obtained via electrospinning of pseudo-boehmite sol/PVP solution

Alumina nanofibers were fabricated by calcination of the polyvinylpyrrolidone (PVP)/pseudo-boehmite nanocomposite precursor fibers formed by electrospinning PVP/ethanol solution of dispersed pseudo-boehmite nanoparticles with and without additive of silica. The evolution of the phase, mechanical property and morphological features of the calcined fibers were studied and the effect of adding SiO₂ on the phase transformation of alumina was discussed. Adding SiO₂ can retard the phase transformation of γ-Al₂O₃ to α-Al₂O₃ and therefore inhibit the growth of alumina grains during calcination. Upon calcining the precursor fibers with 4 wt% SiO₂ additive at 1,300 °C, continuous alumina nanofibers with diameter ranging from 300 to 800 nm were obtained. These continuous nanofibers exhibited good flexibility and could be very promising for applications in filtration and catalyst support.     

Influence of TiO2 impregnated with a novel copper(II) carboxylic porphyrin and its application in photocatalytic degradation of 4-Nitrophenol

A novel 5,15-di-[4-carboxylatomethoxy]phenyl-10,20-diphenylporphyrin, its copper complex and the corresponding metalloporphyrin-TiO₂ photocatalyst were synthesized and characterized by DRS, SEM, XRD, and FT–IR. The photocatalytic effects of anataseTiO₂ impregnated with this copper(II) porphyrin was investigated by photodegradation of 4-nitrophenol(4-NP) in aqueous solution under Xenon lamp irradiation. The results indicated that the photoactivity of copper(II) porphyrin-TiO₂ composite was evidently enhanced by the interaction between carboxyl of the porphyrin molecule and hydroxyls anchored on the TiO₂. Futhermore, the copper(II) carboxylic porphyrin displayed good adsorption behavior and activity of the dye-sensized TiO₂ system.     

Au/TiO2 nanotube catalysts prepared by combining sol–gel method with hydrothermal treatment and their catalytic properties for CO oxidation

A new preparation method for Au/TiO₂ nanotubes (NTs) by combing sol–gel with hydrothermal treatment technique was developed. The TiO₂ NTs calcined at 300 °C were nearly uniform, and the gold particles were distributed homogeneously. The possible formation mechanism was suggested. The 5 % Au/TiO₂ NTs calcined at 300 °C had the best catalytic activity for CO oxidation, and their conversion of CO remained at 100 % during 60 h on stream. This preparation method could improve the thermal stability of Au/TiO₂ nanotube catalysts.     

DNA Nanoribbon-Templated Self-Assembly of Ultrasmall Fluorescent Copper Nanoclusters with Enhanced Luminescence

Fluorescent copper nanoclusters (CuNCs) have been widely used in chemical sensors, biological imaging, and light-emitting devices. However, individual fluorescent CuNCs have limitations in their capabilities arising from poor photostability and weak emission intensities. As one kind of aggregation-induced emission luminogen (AIEgen), the formation of aggregates with high compactness and good order can efficiently improve the emission intensity, stability, and tunability of CuNCs. Here, DNA nanoribbons, containing multiple specific binding sites, serve as a template for in situ synthesis and assembly of ultrasmall CuNCs (0.6 nm). These CuNC self-assemblies exhibit enhanced luminescence and excellent fluorescence stability because of tight and ordered arrangement through DNA nanoribbons templating. Furthermore, the stable and bright CuNC assemblies are demonstrated in the high-sensitivity detection and intracellular fluorescence imaging of biothiols.     

Electrochemical Phase Evolution of Metal-Based Pre-Catalysts for High-Rate Polysulfide Conversion

In situ evolution of electrocatalysts is of paramount importance in defining catalytic reactions. Catalysts for aprotic electrochemistry such as lithium–sulfur (Li-S) batteries are the cornerstone to enhance intrinsically sluggish reaction kinetics but the true active phases are often controversial. Herein, we reveal the electrochemical phase evolution of metal-based pre-catalysts (Co₄N) in working Li-S batteries that renders highly active electrocatalysts (CoS_x). Electrochemical cycling induces the transformation from single-crystalline Co₄N to polycrystalline CoS_x that are rich in active sites. This transformation propels all-phase polysulfide-involving reactions. Consequently, Co₄N enables stable operation of high-rate (10 C, 16.7 mA cm⁻²) and electrolyte-starved (4.7 μL mg_S⁻¹) Li-S batteries. The general concept of electrochemically induced sulfurization is verified by thermodynamic energetics for most of low-valence metal compounds.