A facile approach was developed to prepare highly dispersed TiO2 nanoparticles with selected phase. The crystallization phase of the nanoparticles can be easily tuned from anatase to rutile by the dosage of hydrochloric acid in the reaction system. The crystallite size of the as-prepared anatase TiO2 nanoparticles was ca. 3.2 nm with high dispersion. A transparent TiO2 colloid was obtained by dispersing the as-prepared anatase TiO2 nanoparticles in deionized water without any organic additives added. The concentration of TiO2-H2O colloid can be as high as 1600 g/L. The optical transmittance of TiO2-H2O colloid with a low concentration was nearly 100% in the visible region. Furthermore, anatase TiO2 nanoparticles(TiO2-NPs) showed superior photocatalytic performance compared to rutile TiO2-NPs.
A title organic-inorganic hybrid material 2-amino-3-benzyloxy pyridinium perchlorate was synthesized by slow evaporation at room temperature using 2-amino-3-benzyloxypyridine as the structure-directing agent. The structure of the title compound was determined by means of single-crystal X-ray diffraction at 293 K. The results show that this compound crystallizes in the centrosymetric monoclinic system with a space group of P21/n and lattice parameters of a=0.7025(5) nm, b=1.2635(5) nm, c=1.5766(5) nm, Z=4 and V=1.3905(2) nm3. The crystal structure has been determined and refined to R 1=0.0367 and wR 2=0.1022 using 2326 independent reflections and can be described as a succession of organic and inorganic layers parallel to the bc plane. In this arrangement, hydrogen bonds and van der Waals interactions between different species play an important role in the two-dimensional(2D) network cohesion. This compound was also characterized by means of infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis-differential thermal analysis(TG-DTA). Moreover, protonic conduction of this compound determined by an impedance analyzer has been studied in the temperature range of 303―373 K.
A series of Sr-substituted Gd1-xSr xMnO3(0.1≤x≤0.3) materials was prepared via a standard method involving solid-state reaction. Their crystal structure within the entire doping region was determined to be orthorhombic perovskite type. The magnetic properties of the perovskite Gd1-xSr xMnO3(0.1≤x≤0.3) were thoroughly investigated. It appears that Mn ions with high valence state can induce stronger magnetization, and negative magnetization is evident in the manganites with x=0.1 and x=0.2, suggesting that valence fluctuation plays an important role in such systems. The result of XPS analysis indicates that the valence state of Mn ions is 3.25 and there seems to be excess amounts of oxygen in the structure of Gd0.8Sr0.2MnO3+δ. In addition, the results of magnetization measurements demonstrate that spin reversal occurs only when the applied field is less than 1.99×105 A/m, which presumably could be due to the negative exchange interaction between Mn sub-lattice and Gd sites.
A bimetallic oxalamidino complex of neodymium [(Cp″)2Nd(NR)2C—C(NR′)2Nd(Cp″)2][Cp″=η 5-C5H3-1,3-(SiMe3)2, R=C6H11](2) was obtained via reaction between NdI2 and carbodiimide[RN=C=NR] (R=C6H11)(molar ratio 1:1) in tetrahydrofuran(THF) solution, followed by the addition of [KCp″(THF)](1)(molar ratio 1:2) at a low temperature through a reductive-coupling reaction with carbodiimide. The structure of the intermediate product was confirmed by means of elemental analysis, 1H NMR and 13C NMR. Characterization of the product by single crystal X-ray diffraction confirmed the diamidinate type of structure.
CuV2O6 nanowires were prepared via a simple hydrothermal route using NH4VO3 and Cu(NO3)2 as starting materials. The structures and electrochemical properties of CuV2O6 nanowires were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that the CuV2O6 nanowires are about 100 nm in width and single crystalline grown along [001] direction. CuV2O6 nanowires delivered a high initial discharge capacity of 435 and 351 mA·h/g at current densities of 50 and 100 mA·h/g, respectively. The electrochemical kinetics of the CuV2O6 nanowires was also investigated by means of electrochemical impedance spectroscopy(EIS) and the poor rate performance was observed, which may be attributed to the low ion diffusion coefficient of the CuV2O6 nanowires.
Three new compounds, namely, [Zn(mtpo)2(H2O)4](1), [Cd(mtpo)2·CH3CH2OH] n(2) and [Mn(mtpo)2·CH3CH2OH] n(3)(Hmtpo=4,7-dihydro-5-methyl-7-oxo-[1,2,4]triazolo[1,5-a]pyrimidine), have been synthesized via hydrothermal or solvothermal methods and characterized by means of elemental analyses, Fourier transform infrared(FTIR) spectroscopy, powder X-ray diffraction(PXRD), thermogravimetric analysis(TGA) and single-crystal X-ray diffraction. The results obtained from the single-crystal X-ray diffraction indicate that compound 1 has a mononuclear structure, and crystallizes in a monoclinic crystal system with P21/c space group, which exhibits a 2D supramolecular network constructed by hydrogen bonds and π-π interactions. Compounds 2 and 3 are isomorphous and crystallize in a tetragonal system with space group of I41/a. The M2+(M=Cd, Mn) ions in compounds 2 and 3 have the octahedral coordination geometry. Hmtpo acts as a bridging ligand linking the metal ions to form an infinite 3D framework with 4-connected {42·84} topology. There are hydrogen bonds between the guest ethanol molecules and the mtpo− ligands, which make the ethanol molecules exist in a 3D framework. In addition, luminescent properties of compounds 1 and 2 as well as magnetic property of compound 3 were investigated and water vapor adsorption and nitrogen sorption for compounds 2 and 3 were researched at 298 and 77 K, respectively.
A designed solution route was developed to fabricate size tunable SnO2 hollow microspheres based on the sol-gel theory. The hydrolysis of SnSO4 released protons to form SnO2 particulates and induced the decrease of pH value. To minimize the high surface energy, the SnO2 particulates tended to assemble into large particles, the size of which was affected by the electrolyte concentration or pH value. Elevating SnSO4 content aroused the decrease of the pH value that directed to the shrinkage of the aggregated particle size of SnO2. Size tunable SnO2 hollow microspheres were then rationally fabricated under solvothermal conditions via Ostwald ripening by simply adjusting the SnSO4 concentration. The in situ pH decrease directed to the shrinkage of the particle size from 270 nm to 112 nm. The formation mechanism was confirmed and rationally elucidated by the time dependant morphology evolution. Charge-discharge tests revealed that the reduced particle size aroused an improved lithium ion battery performance.
Fluorescein-rhodamine 6G(Flu-Rh) was synthesized and used as the fluorescence probe for pH measurement based on fluorescence resonance energy transfer(FRET). In the probe, fluorescein fluorophore and pH-sensitive rhodamine 6G hydrazide were used as FRET donor and acceptor, respectively. The values of acidity constant(pK a) and fluorescence quantum yield(Φ) of Flu-Rh were 3.71 and 0.72, respectively. The fluorescence efficiency of Flu-Rh remains almost constant when the pH value of the sample solution changed 10 times in a range of 4.78–7.03 continuously. The present probe is simple and easy-to-use for the pH measurement in acidic media.
A facile approach was reported for the synthesis of nitrogen- and sulfur-co-doped carbon dots(N/S-CDs) by the sulfuric acid carbonization of 1-butyl-3-methylimidazolium 2-amino-3-mercaptopropionic acid(L-cysteine) salt([C4mim][Cys]) ionic liquid. The as-prepared N/S-CDs exhibited a good solubility, excitation-dependent emission behavior, and high resistance to photobleaching. Furthermore, the N/S-CDs were employed as a fluorescent probe for detecting Cu2+ in real water samples with satisfactory recovery.
The conjugate addition reactions of four organolithium reagents to 2,3,4,5-tetraphenylcyclopentadienone (tetracyclone) were investigated to reveal the reactivity of organolithium reagents to tetracyclone. The results show that 1,2-addition products 2,3,4,5-tetraphenyl-1-(2-thienyl)-2,4-cyclopentadien-1-ol(1), 1-n-butyl-2,3,4,5-tetraphenyl-2,4-cyclopentadien-1-ol(2) and 1,2,3,4,5-pentaphenyl-2,4-cyclopentadien-1-ol(3) were synthesized in excellent yields while tetracyclone reacted with 2-thienyllithium, n-butyllithium and phenyllithium, respectively. Interestingly, three 1,2-, 1,4- and 1,6-addition isomers 1-tert-butyl-2,3,4,5-tetraphenyl-2,4-cyclopentadien-1-ol(4), 4-tert-butyl-2,3,4,5-tetraphenyl-2-cyclopenten-l-one(5) and 2-tert-butyl-2,3,4,5-tetraphenyl-3-cyclopenten-l-one(6), were simultaneously obtained by the conjugate addition reaction of tert-butyllithium with larger steric hindrance to tetracyclone. Compounds 1—6 were characterized by 1H and 13C NMR spectra, Fourier transform infrared(FTIR) spectra and mass spectra(MS). The crystal and molecular structures of compounds 1, 2 and isomers 5, 6 were determined by X-ray single crystal diffraction technique. The results imply that the steric hindrance of tert-butyllithium probably play a key role in controlling the conjugate addition reaction. The conjugate addition mechanism of organolithium reagents to tetracyclone was proposed.
Aziridine derivatives of N5-methyltetrahydrofolate were designed and synthesized based on the mechanism of methionine synthase, and their biological activities were investigated as well. The aziridine derivatives 1 and 6 exhibited superior inhibitory activities(IC50: 5.05 and 4.15 µmol/L, respectively) compared to the corresponding chain analogue 4(IC50=24.42 µmol/L). The results suggest that the aziridine derivatives can get potential activities against nucleophilic methionine synthase.
A series of novel 4-phenoxyquinoline derivatives containing 3-amino-2-cyano-acrylamide framework was designed and synthesized, and the in vitro cytotoxic activities of them against five cancer cell lines(HT-29, H460, A549, MKN-45, and U87MG) were evaluated. Most of the compounds exhibited moderate-to-significant cytotoxicity and high selectivity against one or more cell lines as compared with Foretinib. The studies of their preliminary structure-activity relationships(SARs) indicate that the compounds containing methyl groups, especially methyl groups at 4-position of the phenyl ring(moiety B) are more effective. Among them, compound 36 shows the most potent antitumor activities with IC50 values of 0.04, 0.09, 0.67, 0.39 and 1.10 μmol/L against HT-29, H460, A549, MKN-45 and U87MG cell lines, respectively.
Five novel tropos (3R,4R)- and/or (3S,4S)-N-benzyltartarimide-derived biphenylphosphite ligands were synthesized and applied in the Cu-catalyzed asymmetric conjugate addition of diethylzinc to cyclic enones with up to 75% e.e. Compared with the reported ligand 1-N-benzylpyrrolidine-3,4-bis[(R)-1,1’-binaphthyl-2,2’-diyl]phosphite-L-tartaric acid, the issue that L-(+)-tartaric acid backbone and (R)-binaphthyl showed strong matched/mismatched character was solved with these tropos ligands. It was found that the enantioselectivity was mainly controlled by the absolute configuration of N-benzyltartarimide backbone, and both enantiomers of the addition products can be obtained by simply changing the configuration of N-benzyltartarimide substituent.
To investigate the green trinitration method of aromatic compounds, with Lewis acid/ionic liquid as catalyst and HNO3/Ac2O as nitration reagent, a Lewis acid/ionic liquid/HNO3/Ac2O system was established. In various combinations of Lewis acids and ionic liquids, Bi(NO3)3·5H2O/[HMIM]ClO4 proved to be a very efficient catalyst for the trinitration of activated aromatic compounds and reusable for 3 times. Reaction conditions for the trinitration were optimized and yields of the trinitro products were from mild to excellent. This sulfuric acid-free system has the advantages of strong trinitration ability, low environment pollution, low toxicity, low cost and high potential for industrial application.
A series of 6,7-dimethoxyquinazoline derivatives connected by diaryl urea scaffolds was designed, synthesized and their in vitro antitumor activities were evaluated. Most of them showed an excellent potency against the four tested cancer cell lines as compared with sorafenib. Particularly, a promising compound 20 was identified, which showed the most potent antitumor activities with IC50 values of 0.08, 0.09, 0.16 and 0.19 µmol/L against H460, HT-29, MKN-45 and MDA-MB-231 cell lines, respectively. The structure-activity relationship(SAR) analysis indicated that compounds with dimethylamino or diethylamino group at the C4 position of 6,7-dimethoxyquinazoline moiety exhibited superior activities than compounds bearing morpholino groups.
A novel thermostable β-glucosidase(Tnap0602) with β-galactosidase activity was cloned from Thermotoga naphthophila RUK-10 and overexpressed in Escherichia coli BL21(DE3) with the aid of pET28b(+) vector. The recombinant β-glucosidase was purified to homogeneity by heat precipitation and Ni2+-affinity chromatography. The molecular weight of the recombinant enzyme was estimated to be 51 kDa by SDS-PAGE analysis. The optimum temperature for the hydrolyses of p-nitrophenyl-β-D-glucopyranoside and o-nitrophenyl-β-D-galactopyranoside by the recombinant β-glucosidase were both above 95 °C, and the corresponding optimum pH value was found to be the same as 7.0. Thermostability studies show that the half-lives of the recombinant enzyme at 75, 80, 85 and 90 °C are respectively 84, 32, 14, and 3 h, and it is quite stable in a pH range of 5.0–10.0. The K m and V max values of the recombinant β-glucosidase for the hydrolysis of pNPGlu at 80 °C are 0.127 mmol/L and 18389.1 μmol·min−1·mg−1, the corresponding values are 0.625 mmol/L and 6250 μmol·min−1·mg−1 for the hydrolysis of oNPGal, respectively. The enzyme also display the hydrolysis activity for lactose and cellobiose. Galacto-oligosaccharide and alkyl galactopyranosides could be synthesized from Tnap0602 when lactose was used as the transglycosylation substrate, indicating that the thermostable β-glucosidase could be a candidate for industrial application.
Hydrophobins are a type of small amphipathic proteins with a unique self-assembly property, which can be used to modify material surfaces and adsorb enzymes, antibodies and even cells. In this study, a fusion protein consisting of hydrophobin HGFI and green fluorescent protein(GFP) was successfully obtained from Pichia patoris (P. pastoris). Water contact angle(WCA) measurement proves that the wettability of the surfaces of different materials was changed. We further demonstrated the self-assembly ability of HGFI-GFP, which can be used to disperse the multi-walled carbon nanotubes(MWCNTs). Finally, the adsorption of HGFI-GFP onto the surface of the tissue engineering material poly(ε-caprolactone)(PCL) was evaluated by detecting the fluorescence of the fusion protein itself. The resalt demonstrates that both the basic self-assembly activity of the HGFI domain and the functional activity of the GFP domain were still remained.
The manufacture of 1,1-dichloroethylene(1,1-DCE) usually employs liquid phase method to perform the dehydrochlorination of 1,1,2-trichloroethane(TCE), where large amounts of high-concentration salty wastewater is produced inevitably. It has been a long-term goal to achieve the gas phase synthesis of 1,1-DCE via supported catalysts. In this work, the gas-phase synthesis of 1,1-DCE from TCE was studied in the presence of pentaethylenehexamine( PEHA) supported on silica. High and stable selectivity to 1,1-DCE(up to 98%) was obtained, which could be ascribed to the relatively strong basicity of PEHA according to a proposed E2 mechanism. The formation of PEHA chloride from the HCl generated in situ was detected and was considered to be the main reason for the deactivation of PEHA catalyst.
Density functional theory(DFT) calculations were carried out to investigate the geometry structures, redox properties and second-order nonlinear optical(NLO) properties of ferrocene(Fc)-dithiolenes hybrid complexes. The switchable second-order NLO properties of these complexes are induced by the redox process. The oxidized process significantly affects the geometrical structures of the dithiolene moieties, that is, the embowed dithiolene moieties change into planar structures. It supports that the dithiolene moieties are the oxidized center. The β tot values of the cationic species are at least 4 and 10 times those of their corresponding parent complexes, respectively. Further, the time-dependent DFT calculation illustrates that the low-energy absorption(which is helpful for the large NLO response) is mainly assigned to intra-ligand charge transfer [π(ex-dithiolene)→π*(ex-dithiolene)]. These results suggest the potential use of the novel Fc-based dithiolenes complexes as versatile and fascinating NLO switching materials.
To develop a new type of non-oxidant electron acceptors for water oxidation, 3-(methyl)phenyl-(3,5-dimethyl-1H-pyrrol-2-yl)methanone modified silica(SiO2@py) was synthesized and used as host to Co4O4 cubane forming nanoparticles(SiO2@pyCo4). In the presence of Ru(bpy)3 2+ and under the irradiation of white LED(light emitting diode) light(10 W), SiO2@pyCo4 can catalyze water oxidation without extra electron acceptor(e.g., Na2S2O8). Moreover, the turnover frequency(TOF) value of SiO2@pyCo4 is larger than that of Co4O4 cubane under the same conditions, and the longer lasting time of SiO2@pyCo4 indicates that SiO2@py can enhance the stability of Co4O4 in water. Our results provide an economic route to develop dioxygen evolution systems based on the assembly of organic electron acceptor modified silica with active cobalt complexes.
Three dipyrrin-containing metal complexes and a boron dipyrromethene(BODIPY)-containing complex were designed and synthesized. The photophysical properties, electrochemical behaviours and photovoltaic performance were extensively investigated. Density functional theory calculations were also performed on those complexes. These complexes, together with electron-acceptor [6,6]-phenyl-C71-butyric acid methyl ester, were utilized for the fabrication of solution-processed bulk heterojunction solar cells as the electron-donor materials. The more efficient electron acceptor BODIPY segment renders a lower energy gap and a relatively better photovoltaic conversion efficiency of 0.58%. These results prove that BODIPY segment has a great potential for constructing efficient organic solar cell materials.
Based on a full device model adopting three-dimensional Pauli master equation approach, the charge carrier loss process due to poor extraction channels between electrode and active layer in polymer bulk heterojunction( BHJ) solar cells was studied. The influence of barrier height on device performance was simulated to reveal the importance of electrode improvement. It was found that relatively large extraction barrier height(over 0.40 eV) can lead to the significant diminishing of the overall charge collection efficiency, since bimolecular recombination rate would increase to a high level due to enhanced space charge accumulation effect near electrodes. In contrast, the percentage of charge carrier annihilated due to geminate recombination did not change significantly with barrier height variation. Our simulation results may provide the basis for a more accurate model and potential direction of polymer BHJ solar cells improvement.
The stability of pyrotechnic composition used in flame detonator was studied at severe temperatures (–70―130 °C) for 5 d. For single N-LTNR(normal lead styphnate), camera was used to observe the shape and colour of N-LTNR in the DSC(differential scanning calorimetry) furnace during continuous heating and cooling processes. Based on the DSC-TGA(thermogravimetric analysis) results, it can be seen that when the temperature exceeded 110 °C, N-LTNR lost its crystal water, making the energetic material become darker in colour, smaller in dimension, lager in volume and lighter in weight(3.416%); when the temperature was below −40 °C, the phenomenon of sample broking, jumping and cracking happened. For the N-LTNR and Pb(N3)2(lead azide) double layers, the loss of N-LTNR’s crystal water at the temperature higher than 110 °C caused the hydrolysis reaction of Pb(N3)2, and the purity of Pb(N3)2 measured after the temperature cycling decreased from 98.6% to 95.26%. For the flame detonator, the height and diameter of the flame detonator were measured and no apparent changes of them were found. The p-t(pressure-time) test shows that the peak pressure was decreased by 3.9%. Therefore, the operating temperature of this flame detonator should be limited to −40–110 °C.
LiMn2O4 nano-wires with ideal size distribution were readily synthesized by flux method. Samples prepared conventionally were used as the comparison references to investigate the effect of flux. The structural, morphological and electrochemical properties of nano-sized materials were examined by powder X-ray diffraction(XRD) analysis, scanning electron microscopy(SEM) and charge-discharge cycling analysis. Results from galvanostatic charge-discharge analysis show that the samples prepared at 700 °C via flux method(FM-700) afford the highest initial discharge capacity of 125.5 mA·h/g between 3.0 to 4.3 V at a rate of 0.2 C. After 50 cycles, a cycling retention of 89.6% is evident. Overall, the LiMn2O4 nano-wires developed in this work seem to be promising cathode materials for lithium ion batteries suitable to different energy-saving settings.
The electronic structures and bonding properties of the (110) polar terminations of cubic PbTiO3 were examined by the first-principles calculations at the generalized gradient approximation level. Two stoichiometric (PbTiO and O2) and three nonstoichiometric(TiO, Pb, and O) terminations were considered in this study. With the aid of the calculated electron density differences, atomic charges, band structures, and densities of states, the charge redistributions and electronic properties were evaluated in detail. Furthermore, based on the calculated results of the cleavage energies, relaxation energies, and surface energies of the investigated terminations, the charge compensation by the modification of the surface stoichiometry and the fillings of surface states were thermodynamically evaluated.
A density function theory(DFT) study was made on three dyes based on hydroxamate with different ligands[terpyridine, isothiocyanate(NCS) and 2,2′-bis(thienyl)-tripyrrinate(2-BTTP)] to investigtate their device performance optimization in dye sensitized solar cell(DSSC). Based on the adsorbed dye on TiO2 (101) surface, the ground state geometry structures, electronic structures, absorption spectra and correspongding charge transfer properties were analysed in detail. The results indicate that the ligand replacement of terpyridine by NCS and 2-BTTP improves the low-energy region absorption of hydroxamate based dyes significantly. The electron injection and light harvesting capability of hydroxamate based dyes are enhanced by NCS and 2-BTTP ligands as well. In the visible region, hydroxamate based dyes have the potentials to become panchromatic light absorbers according to our research.
Salicylhydroxamic acid(SHA) was covalently grafted onto chloromethylated crosslinked polystyrene spheres(CMCPS) by the Friedel-Crafts alkylation reaction. The amount of SHA on CPS was found to be mainly dependent on the amount of Lewis acid(SnCl4) used and the reaction temperature. Under optimized conditions, the amount of SHA attached to CPS could reach up to 0.43 g/g CPS. Transition metal ions[Co(II), Cu(II), Fe(III) or Mn(II)] were then introduced into the resulting SHA-functionalized microspheres(SHA/CPS) through SHA-metal ion chelation. The obtained microspheres MSHA/CPS were explored as biomimetic catalysts for the aerobic oxidation of ethylbenzene(EB) to ethylbenzene hydroperoxide(EBHP). Among the four supported metal catalysts, FeSHA/CPS showed the highest catalytic activity and good reusability, indicating its great potential as an effective heterogeneous catalyst for the aerobic oxidation of hydrocarbons under mild conditions.
Hierarchical TiO2 flower-spheres assembled from porous nanosheets-stacked of nanoparticles were synthesized by a simple hydrothermal method with one-step. The as-prepared TiO2 flower-spheres showed a diameter range from 200 nm to 550 nm and a large surface area of 188 m2/g. A double layer photoanode made of P25 nanoparticles and as-prepared TiO2 flower-spheres was fabricated for the dye sensitized solar cells(DSSCs). The efficient light scattering and dye absorption of the photoanode can be attributed to the top-layer of hierarchical TiO2 flower-spheres. DSSCs based on the double layers photoanode exhibit a higher energy conversion efficiency of 8.11% with a short-circuit photocurrent density of 17.87 mA/cm2, indicating that there is an increase of 38% in the conversion efficiency compared to those based on electrode P25(5.91%, 14.09 mA/cm2).
Coaxial nanocable consisted of p-type Cu2O nanowires and n-type TiO2 nanotubes arrays was prepared in the porous anodic aluminum oxide(AAO) template via the sol-gel method and subsequent electrodeposition method. X-ray diffraction analysis identified an anatase structure of the TiO2 nanotubes and cubic structure of the Cu2O nanowires. The obtained samples were also characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive X-ray spectroscopy(EDS). The diffrence of open circuit potential of the coaxial nanocable electrode was larger than that of the TiO2 nanotubes electrode under ultraviolet illumination, which means doping with Cu2O could improve the photovoltage effectively. Meanwhile, nanocable arrays exhibited a high activity for photodegrading Rhodamine B under Xe lamp irradiation and the photocatalysis degradation efficiency was up to 98.69% after degradation for 7 h. The enhanced photocatalytic activity could be attributed to the high migration efficiency of photoinduced electrons, which may suppress the charge recombination effectively.
TiO2 nanotubes supported amorphous Co-B(Co-B/TNTs) catalyst was prepared via impregnationchemical reduction procedure. The catalyst was characterized with transmission electron microscopy(TEM), ammonia temperature-programmed desorption(NH3-TPD), thermogravimetry-differential thermal analysis(TG-DTA), Fourier transform infrared spectroscopy(FTIR) and Raman spectroscopy. The effects of temperature and ratio of CO to H2 on the hydroformylation of 1-octene were studied. At an optimized reaction temperature(150 °C) and volume ratio of CO to H2(2:1), the conversion of 1-octene can reach 97.4% with a selectivity of 23.1% for total aldehydes and n/i-aldehyde molar ratio of 40:60. To obtain higher selectivity for linear aldehydes, Co-B/TNTs modified with triphenylphosphine for the hydroformylation of 1-octene were investigated. When molar ratio of P/Co was 4, the yield of total aldehydes was the highest(31.6%) with a good selectivity for linear product(n/i-aldehyde molar ratio was 70:30). In recycle use, the Co-B/TNTs catalyst modified with triphenylphosphine could be reused five times without reducing the activity and selectivity obviously. For a comparative study, all the Co-B/TNTs to catalyze the hydroformylation of other olefins exhibited high conversion under the optimized conditions.
The transport properties of several alkali fluoride high temperature ionic liquids(LiF, NaF, KF, RbF and CsF) were studied in a range of 980―1400 K and the temperature dependences of the viscosity and density were interpreted, in agreement with the classical equations characterizing the viscous flow(Arrhenius, Batchinski, Eyring and Frenkel). The experimental results reveal the validity of these equations even at high temperatures, suggesting that no significant structural changes of alkali fluorides occurred in the studied temperature range. Our results clearly demonstrate that the mentioned thermo-physical properties can be used as powerful tools in the further investigations of the ionic interactions governing the alkali fluoride molten salts.
A series of tri(alkoxyl)benzene-fullerene dyads(PCBB-Cn, n=4, 6, 8, 10, 12) with varied tri(alkoxyl) chain lengths was designed, synthesized and used as acceptor materials in polymer solar cells(PSCs). The five fullerene dyads possess similar absorption spectra in dilute solution, decreased glass-transition temperature(T g) and gradually elevated lowest unoccupied molecular orbital(LUMO) energy levels from–3.87 eV to–3.73 eV with the increase of the alkoxy chain length. In the fabrication of PSCs with poly(3-hexylthiophene)(P3HT) as donor and the fullerene dyads as acceptor, PCBB-Cn with longer tri(alkoxyl) chains and lower Tg can induce crystalline structure of P3HT during spin-coating the photoactive layer at room temperature and form nanoscale phase separated interpenetrating network of P3HT:PCBB-C n blend films, which results in the improvement of photovoltaic performance of PSCs. A power conversion efficiency of 3.03% for the PSCs based on P3HT:PCBB-C10 was obtained without thermal annealing or solvent annealing. The thermal and solvent annealing-free fabrication using the fullerene dyads as acceptor is very important for the roll to roll production of PSCs with flexible large area.
Triticale straw(TS) and refined triticale straw(RTS) were characterized by scanning electron microscope( SEM), Fourier transform infrared spectroscopy(FTIR) and thermogravimetric analysis(TGA) in detail, and their application in polypropylene(PP) composite was explored. RTS was obtained by refining TS with environmentally benign processes, by which hemicelluloses and lignin were effectively removed. This was proved by FTIR analysis. The effect of cellulose content on the composite thermal stability and mechanical properties was also examined. RTS has better thermal stability than TS because RTS has lower flammable noncellulose ratio. T 5%(temperature with mass loss of 5%) of RTS could be more than 200°C. It is high enough to meet the requests of processing most polyolefin composites. Both TS and RTS acted as nucleating agents in PP crystallization process. TS was proved to be a filler of the composite, and RTS to be a reinforcing material for the composite. The flexural strength and modulus of RTS/PP increased about by 5% and more than 100%, respectively, compared with those of PP, when the mass fraction of RTS and compatibilizer were 30% and 2%, respectively. The thermal stability of RTS/PP composites was also better than that of TS/PP composites.
Carbon nanotubes(CNTs) have received wide application and investigation because of their unique electronic, chemical and mechanical properties. But the self-aggregation of CNTs limits their practical application and study. In order to disperse CNTs effectively, polymers, such as polyglycerol and its derivatives, are adopted as dispersants in view of their strong interaction with CNTs. In order to understand the interaction between CNTs and glycerol in water in detail, a series of simulations has been conducted to investigate the interaction between them and analyze the influences of CNTs diameter and temperature. All the analyses indicate that the glycerol molecules are prone to aggregate around CNTs with the addition of CNTs. This is mainly due to hydrophobic interaction. It is confirmed that this aggregation is influenced by CNTs diameter and the temperature to some degree. This work will establish the basis for the exploration of polyglycerol and its derivatives interacting with CNTs and provide an invaluable guide to seek for emergent dispersants for CNTs.
Large scale NiFe2O4 nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe2O4 annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Fe– ions into NiFe2O4 nanowires. In the beginning stage of synthesizing process, the shape of NiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400 °C to 600 °C. At last they transformed into nanoparticles from 700 °C to 1000 °C. Thus, the optimized annealing temperature was selected as 600 °C because the NiFe2O4 obtained at 600 °C(N600) exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m2/kg and the lowest coercivity(H c) of 8914 A/m.
Poly(L-glutamic acid)(PLGA) was grafted onto the surface of mesoporous silica nanoparticles(MSN) via the ring opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride(BLG-NCA) and its subsequent deprotection of benzyl groups. The PLGA chains were cross-linked with cystamine, and thus forming a type of redox responsive drug delivery system(MSN-cPLGA). The structures were characterized by Fourier transform infrared spectrometry(FTIR), transmission electron microscopy(TEM) and energy disperse spectrometry(EDS), demonstrating that disulfide groups existed on the surfaces of MSN-cPLGA particles. The thermal gravimetric analysis(TGA) results show that the PLGA mass fraction is about 33.4% in the MSN-cPLGA hybrid. The in vitro drug release experiments showed that the MSN-cPLGA hybrid can realize the controlled release of model drugs(5-fluorouracil) in response to redox environment. Even 0.1 mmol/L dithiothreitol(DTT) can accelerate the drug release speed, and a concentration of 10.0 mmol/L DTT is higher enough to trigger the open of cross-linked PLGA network so as to realize rapid release of drugs. All the results demonstrate that the cross-linked PLGA chains on the surface of MSN could act as efficient gatekeepers to control the on-off of the pores, showing potential application in drug delivery system.
Locust is a common flying insect. Locust wings were used as biomimetic templates to fabricate multi-functional polymer(polydimethylsiloxane, PDMS) films by soft lithography. The microstructure and wettability of the natural and artificial locust wing surfaces were investigated by means of a scanning electron microscope(SEM) and a video-based contact angle meter. The natural locust wing surface exhibits complicated hierarchical structures and high adhesive superhydrophobicity(contact angle 152°). The prepared polymer film faithfully reproduces the surface microstructures of the bio-template, and displays a good hydrophobicity and high adhesion(contact angle 144°). The complex wettability of the natural and artificial locust wing surfaces ascribes to the cooperative effect of hydrophobic composition and multi-dimensional rough microstructures. This work not only promotes our understanding of the wetting mechanism on bio-surfaces, but offers an inexpensive and effective approach for biomimetic fabrication of multi-functional interfacial materials.