Characterization of charging effect of citrate-capped Au nanoparticle pentacene device

Capacitance–voltage hysteresis for a non-volatile memory was realized in a metal–pentacene–insulator–silicon (MPIS) device using gold (Au) nanoparticles (NPs) intervened between pentacene and SiO₂ insulator. A memory window higher than 2.0 V was obtained under (±) 5 V programming sweeping range. The SiO₂ as thick as 30 nm was adopted as the dielectric layer, and 3-aminopropyl-triethoxysilane (APTES) was used for self-assembling of Au NPs monolayer. In addition, citrate-functionalized Au NPs was dip-coated and used as charge storage elements. Formation of a monolayer of the Au NPs was confirmed by HR-SEM and AFM. Capacitance–voltage hysteresis in this study was resulted from the charge storage in the layer of Au NPs.     

Effects of molecular weight on electroluminescence of nanogold‐bonded poly(9,9‐dioctylfluorene‐alt‐thiophene) at a constant polymer‐to‐gold weight ratio

The effects of molecular weight on electroluminescent properties of the light emitting polymeric nanocomposite, poly(9,9‐dioctylfluorene‐alt‐thiophene) with chemically bonded gold nanoparticles (PDOFT‐Au), have been studied under a condition of constant polymer‐to‐gold weight ratio. The polymer, PDOFT, was first synthesized via the Suzuki cross‐coupling reaction and then bonded to in situ‐formed gold nanoparticles (AuNPs) via terminal thiol functional groups which had been generated during the quenching of polymerization. A series of PDOFT‐Au's of various molecular weights have thus been synthesized. At a constant polymer‐to‐gold weight ratio, the average size of gold nanoparticles (AuNPs) increased with an increase in the molecular weight of PDOFT. Although an increased molecular weight led to a red shift in UV‐absorption and PL spectra as well as an increased PL quantum efficiencies (?_PL) for all samples (both PDOFT and PDOFT‐Au), the effect of AuNPs bonding became more noticeable when the molecular weight was higher. As for light emitting diode (LED) device fabrication, an increase in the molecular weight of PDOFT also led to a red shift in the EL spectra of the fabricated LED devices. Nevertheless, PDOFT‐Au, compared with PDOFT, had a lower threshold voltage, an increased brightness and current density, and an improved photometric efficiency. Moreover, the photometric efficiency increased with an increase in the molecular weight of the polymer, from 0.298 cd/A for PDOFT‐Au3 up to 0.645 cd/A for PDOFT‐Au1. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Microwave-Assisted Base-Free Oxidation of Glucose with H2O2 on Gold- and Manganese-Containing SBA-15—Insight into Factors Affecting the Reaction Pathway

The aim of this work was to gain insights into the role of manganese in MnSBA-15 support for gold in the base-free glucose oxidation with H₂O₂ using a microwave reactor. MnSBA-15 (manganese—acidity source) and SBA-15 (for comparison) were modified with Au (2.2 wt. %) and Cu (for comparison). The physicochemical properties of the catalysts were investigated by XRD, N₂ ads/des, TEM, UV-vis, XPS, pyridine adsorption combined with FTIR, ATR-FTIR, and 2-propanol decomposition. The effects of the Mn presence in the support, Au NPs size that determines the number of active Au centers, and the Fermi energy (E_F), together with the effects of the pore size, reaction temperature, and time on the activity and selectivity of the applied catalysts were assessed and discussed. It has been demonstrated that the presence of Mn generated Lewis acid centers which did not participate in glucose and H₂O₂ adsorption, and thus, were not directly involved in the reaction pathway. Both reagents were adsorbed on gold nanoparticles. H₂O₂ was decomposed to molecular oxygen which oxidized glucose to gluconic acid (50–90% of glucose conversion depending on the reaction time and ~100% selectivity). The presence of manganese in MnSBA-15 was responsible for increased Au NPs size and only slightly influenced the negative charge on gold particles. To achieve effective activity a compromise between the number of active gold species and the level of E_F has to be reached (for 5.7 nm Au NPs).     

Ambient temperature CO oxidation over gold nanoparticles (14 nm) supported on Mg(OH)2 nanosheets

Au/Mg(OH)₂ catalysts with two different sizes (4 and 14 nm) of Au nanoparticles (NPs) have been prepared by depositing pre-fabricated Au NPs onto Mg(OH)₂ nanosheets (NSs). It was found that 14 nm Au NPs supported on Mg(OH)₂ exhibited unexpected activity for CO oxidation at ambient temperature that could be comparable with those of Au NPs of 4 nm. The Mg(OH)₂ support was suggested to be responsible for the observed catalytic activity of larger gold supported catalysts.     

In situ preparation of Au or Ag nanoparticles in the presence of hyperbranched poly(amidoamine)s with hydrophobic end‐groups as nanoreactors and reductants

Hyperbranched poly(amidoamine)s with methyl ester terminals (HPAMAM‐COOCH₃) were used as nanoreactors and reductants to prepare gold or silver nanoparticles (Au NPs or Ag NPs). HPAMAM‐COOCH₃ could bind AuCl₄ ⁻ (or Ag⁺) and then reduce AuCl₄ ⁻ (or Ag⁺) into Au NPs (or Ag NPs) through their internal amines, while the external methyl ester groups prevented the aggregation of polymers. The formation of Au NPs or Ag NPs was verified using transmission electron microscopy (TEM), ultraviolet‐visible spectroscopy (UV‐Vis), X‐Ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), and thermogravimetric analysis (TGA), confirming the formation of Au NPs or Ag NPs with small particle size and low size distribution.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Reduced graphene oxide–gold nanoparticle membrane for water purification

The reduced graphene oxide–gold nanoparticle (rGO–Au NP) membranes are prepared by vacuum filtration method. The sizes of the Au NPs on the surface of the rGO are about 8–10 nm, and the lattice spacing of Au NPs is 0.0241 nm, which is relative to the cubic lattice of the gold crystal. The layer-by-layer stacking structure of rGO–Au NP membrane can be observed clearly by field emission scanning electron microscopy. The water flux of the rGO–Au NP membrane is as high as 204.1 L m^?2 h^?1 bar^?1, and its retention for Rhodamine B (RhB) is as high as 99.79%.     

Synthesis,spectral properties and dyeing on polyester of monoazo dyes from indol‐2‐one derivatives

Three series of phenylazo disperse dyes were prepared by coupling diazotised 4‐aniline dyes with 5‐indol‐2‐one dyes. The structures of these dyes were determined by proton nuclear magnetic resonance, Fourier Transform–infrared and elemental analysis. The effects of solvent on the ultraviolet–visible absorption spectra of these dyes were studied. The dyes displayed a λ_max shift of between 399 and 438 nm. The dyes were finally applied in the dyeing of polyester fibres in order to investigate their colour range and dyeing properties. Most of the dyes displayed high rubbing fastness and good washing and sublimation fastnesses on polyester fibres.     

Effect of Carbon Nanotubes and Carbon Nanotubes/Gold Nanoparticles Composite on the Photocatalytic Activity of TiO2 and TiO2‐SiO2

A carbon nanotube (CNT)/gold nanoparticle (NP) nanocomposite was synthesized by simultaneously reducing the Au ions and depositing Au NPs on the surface of a CNT. The functional groups were investigated with Fourier transform infrared spectra. From the Raman spectra, the D‐band and G‐band of the CNT were identified. The deposition of nanometer‐sized Au NPs on the CNT sites was observed by transmission electron microscopy. The photodegradation of methylene blue (MB) in aqueous solutions was studied using various photocatalysts, including TiO₂, TiO₂‐SiO₂, CNT/TiO₂, CNT/TiO₂‐SiO₂, Au/TiO₂, CNT‐Au/TiO₂, and CNT‐Au/TiO₂‐SiO₂ composites. CNT addition leads to a synergic effect, improving the photoactivity of the catalysts. A possible physically based mechanism was proposed involving the reduction of electron‐hole recombination and fast electron‐transfer possibility.     

Formation of microcapsules of medicines by the rapid expansion of a supercritical solution with a nonsolvent

The rapid expansion from a supercritical solution with a nonsolvent (RESS‐N) was applied to the formation of polymeric microcapsules containing medicines such as p‐acetamidophenol, acetylsalicylic acid, 1,3‐dimethylxanthine, flavone, and 3‐hydroxyflavone. A suspension of medicine in carbon dioxide (CO₂) containing a cosolvent and dissolved polymer was sprayed through a nozzle to atmospheric pressure. The pre‐expansion pressure was 10–25 MPa, and the temperature was 308–333 K. The polymers were poly(L ‐lactic acid) (molecular weight = 5000), poly(ethylene glycol) (PEG; PEG4000, molecular weight = 3000; PEG6000, molecular weight = 7500; and PEG20000, molecular weight = 20,000), poly(methyl methacrylate) (molecular weight = 15,000), ethyl cellulose (molecular weight = 5000), and PEG–poly(propylene glycol)–PEG triblock copolymer (molecular weight = 13,000). The solubilities of the polymers as coating materials and these medicines as core substance were very low in CO₂. However, the solubilities of these polymers in CO₂ significantly increased with the addition of low molecular weight alcohols as cosolvents. After RESS‐N, polymeric microcapsules were formed according to the precipitation of the polymer caused by a decrease in the solvent power of CO₂. This method offered three advantages: (1) enough of the coating polymers, which were insoluble in pure CO₂, dissolved; (2) the microparticles of the medicine were encapsulated without adhesion between the particles because a nonsolvent was used as a cosolvent and the cosolvent remaining in the mixture was removed by the gasification of CO₂; and (3) the polymer‐coating thickness was controlled with changes in the feed composition of the polymer for drug delivery. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 742–752, 2003     

New soybean oil–styrene–divinylbenzene thermosetting copolymers. I. Synthesis and characterization

The cationic copolymerization of regular soybean oil, low‐saturation soybean oil (LoSatSoy oil), or conjugated LoSatSoy oil with styrene and divinylbenzene initiated by boron trifluoride diethyl etherate (BF₃·OEt₂) or related modified initiators provides viable polymers ranging from soft rubbers to hard, tough, or brittle plastics. The gelation time of the reaction varies from 1 × 10² to 2 × 10⁵ s at room temperature. The yields of bulk polymers are essentially quantitative. The amount of crosslinked polymer remaining after Soxhlet extraction ranges from 80 to 92%, depending on the stoichiometry and the type of oil used. Proton nuclear magnetic resonance spectroscopy and Soxhlet extraction data indicate that the structure of the resulting bulk polymer is a crosslinked polymer network interpenetrated with some linear or less‐crosslinked triglyceride oil–styrene–divinylbenzene copolymers, a small amount of low molecular weight free oil, and minor amounts of initiator fragments. The bulk polymers possess glass‐transition temperatures ranging from approximately 0 to 105°C, which are comparable to those of commercially available rubbery materials and conventional plastics. Thermogravimetric analysis (TGA) indicates that these copolymers are thermally stable under 200°C, with temperatures at 10% weight loss in air (T₁₀) ranging from 312 to 434°C, and temperatures at 50% weight loss in air (T₅₀) ranging from 445 to 480°C. Of the various polymeric materials, the conjugated LoSatSoy oil polymers have the highest glass‐transition temperatures (T_g) and thermal stabilities (T₁₀). The preceding properties that suggest that these soybean oil polymers may prove useful where petroleum‐based polymeric materials have found widespread utility. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 658–670, 2001     

Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography, respectively, and samples were collected to measure properties. According to the elemental analysis, molecular weight and ¹H-NMR data, average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner (B-L) method and several corrections. And then, the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation, and the molecular size was gotten via the radius of gyration analysis. The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55–0.70 nm in vacuum and 0.60–0.90 nm in toluene solution. With molecular weight increasing, the molecular size in vacuum and toluene solution also increased. Due to the swelling behavior of solvent, the alkyl side chains of heavy oil molecule in solution were more stretched. Thus, the molecular size in toluene solution was larger than that in vacuum.     

Synthesis of Densely Immobilized Gold-Assembled Silica Nanostructures

In this study, dense gold-assembled SiO₂ nanostructure (SiO₂@Au) was successfully developed using the Au seed-mediated growth. First, SiO₂ (150 nm) was prepared, modified by amino groups, and incubated by gold nanoparticles (ca. 3 nm Au metal nanoparticles (NPs)) to immobilize Au NPs to SiO₂ surface. Then, Au NPs were grown on the prepared SiO₂@Au seed by reducing chloroauric acid (HAuCl₄₎ by ascorbic acid (AA) in the presence of polyvinylpyrrolidone (PVP). The presence of bigger (ca. 20 nm) Au NPs on the SiO₂ surface was confirmed by transmittance electronic microscopy (TEM) images, color changes to dark blue, and UV-vis spectra broadening in the range of 450 to 750 nm. The SiO₂@Au nanostructure showed several advantages compared to the hydrofluoric acid (HF)-treated SiO₂@Au, such as easy separation, surface modification stability by 11-mercaptopundecanoic acid (R-COOH), 11-mercapto-1-undecanol (R-OH), and 1-undecanethiol (R-CH₃), and a better peroxidase-like catalysis activity for 5,5′-Tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂) reaction. The catalytic activity of SiO₂@Au was two times better than that of HF-treated SiO₂@Au. When SiO₂@Au nanostructure was used as a surface enhanced Raman scattering (SERS) substrate, the signal of 4-aminophenol (4-ATP) on the surface of SiO₂@Au was also stronger than that of HF-treated SiO₂@Au. This study provides a potential method for nanoparticle preparation which can be replaced for Au NPs in further research and development.     

Ir promotion of TiO2 supported Au catalysts for selective hydrogenation of cinnamaldehyde

We synthesized Ir-on-Au (Au–Ir) nanoparticles (NPs) using 8–9 nm Au NPs, which had a partial coverage of Ir. Both the studied systems allowed the obtainment of cinnamyl alcohol with high selectivities (> 83%). However, Au–Ir/TiO₂ delivered a hydrogenation rate 5 times higher than that of Au/TiO₂. The deposition of Ir onto the surface of Au and the presence of surface Au–Ir alloy were confirmed by UV–vis and HRTEM respectively. Moreover. Moreover, the strongly shifted XPS binding energy implyed the electron transfer from Ir to Au, which was believed to be responsible for the enhanced H₂ activation capacity of Au.     

Poly(vinyl alcohol) triggers Au nanoparticles formation for near-infrared radiation-responsive gels and nanofibers

The capability of poly(vinyl alcohol) (PVA) to reduce noble metal ions and, in turn, to prepare one-step hybrid systems that exhibit near-infrared radiation (NIR) light-responsiveness has been barely explored. The aim of this work was to elucidate whether gold nanoparticles (Au NPs) could be spontaneously formed in PVA gels suitable to be used as syringeable depots or to prepare electrospun nanofibers. To check the hypothesis of that the gold counterion may play a role in the Au NPs formation process, two different gold salts (HAuCl₄ and AuAc₃) were used. Localized surface plasmon resonance bands were monitored during the incubation of PVA-gold salt gels, and the photoresponsive capability of the newly formed Au NPs inside gels was investigated during laser irradiation at 808 nm. HET-CAM assay suggested good biocompatibility. Then, the feasibility of producing electrospun hybrid PVA-based mats that exhibit light-responsive photothermal features was explored here for the first time. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48811.     

一种新颖的含黄酮结构可交联高分子染料的合成与染色性能研究(英文)

A yellow crosslinking polymeric dye was prepared by grafting the flavone moiety containing azo chromophore onto polyvinylamine backbone.The λ max of this polymeric dye in water is 382 nm.The polymeric dye is fixed to silk and cotton with a crosslinking agent,2-chloro-4,6-di(aminobenzene-4’-β-sulphatoethylsulphone)-1,3,5-s-triazine,which acts as a bridge between the fiber and dye molecules.The fixation of this polymeric dye reaches 99% and the dyed samples exhibit excellent rubbing and washing fastness.     

Hydrolysis of used frying palm olein and sunflower oil catalyzed by porcine pancreatic lipase

The enzymatic hydrolysis of frying used vegetable oils with different degrees of alteration were measured using porcine pancreatic lipase (acylglycerol acylhydrolase EC 3.1.1.3). Successive frying of potatoes significantly increased the level of total polar lipid content in the palm olein from 9.3±0.1 mg/100 mg oil to 26.4±0.3 mg/100 mg oil after 90 fryings, and from 4.0±0.1 mg/100 mg oil to 27.7±0.3 mg/100 mg oil in sunflower oil after 60 fryings. Triacylglycerol polymers, triacylglycerol dimers, and oxidized triacylglycerols also increased 37-, 7.9-, and 7.5-times in palm olein, respectively, and 56-, 22-, and 4.7-times in sunflower oil, respectively. However, diacylglycerols and free fatty acid levels related to hydrolytic alteration did not increase with the number of fryings in both oils. The substrate concentration in the reactor was determined by calculating the molecular weight of each oil showing a different degree of alteration. We compared the methodology used by us and that used by other authors. The results show that the methods are reproducible and that the values obtained are in concordance with theoretical values. The kinetic parameters apparent Michaelis-Menten constant (K _M ^app ) and apparent maximum velocity of hydrolysis (V _max ^app ) were different in unused palm olein (5.1±0.7 and 166±7.6, respectively) than in sunflower oil (2.2±0.3 and 62±2.2, respectively). However, changes inK _M ^app andV _max ^app were not related to the degree of alteration of the oils.     

Influence of two‐stage drawing conditions on ultradrawing behavior of gel films of ultrahigh‐molecular‐weight polyethylene and low‐molecular‐weight polyethylene blends

The influence of two‐stage drawing conditions on the ultradrawing behavior of the gel films of ultrahigh‐molecular‐weight polyethylene/low‐molecular‐weight polyethylene blends is reported in this article. The critical draw ratios (λ_c) of the gel films prepared near their critical concentrations were found to depend significantly on the draw ratio attained in the first drawing stage (D_1r) and on the temperature utilized in the second drawing stage (T_sec). After drawing the gel films to a fixed draw ratio in the first drawing stage, each two‐stage drawn gel film was made to exhibit a maximum λ_c (λ_cmax) by drawing the drawn gel film at its corresponding optimum T_sec. In addition, the optimum T_sec was found to increase significantly with the D_1r value of the drawn gel films. It is worth noting, on the other hand, that the λ_cmax of two‐stage drawn gel films increased consistently with an increasing D_1r until its value reached an optimum value of 160. These results clearly suggest that, as T_sec and D_1r are increased to their optimum values, the λ_cmax of the two‐stage drawn gel films can be improved further so as to be higher than those of the corresponding one‐stage drawn gel films. These interesting phenomena were investigated in terms of reduced viscosities of the solutions and by an analysis of the thermal, birefringence, and tensile properties of the drawn gel films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1890–1901, 2001     

Ion Exchange Resins for Gold Cyanide Extraction Containing a Piperazine Functionality, 2. Study of the Gold Extraction Reaction

Ion exchange technology is offered as an alternative to activated carbon for gold cyanide recovery. A new type of ion‐exchange resin (PS‐PIP) incorporating a piperazine group, linked to a styrene‐divinylbenzene macroporous network, is described. The extraction of Au(CN)₂^– and other metal cyanides with the PS‐PIP resin involves three modes of metal extraction: the protonated secondary amine groups of the resin (at acidic pH conditions), the free amine groups of the resin (at neutral and basic pH values) and the small portion of the quaternary ammonium groups participate in the gold extraction mechanism. The gold cyanide extraction reaction on the polymeric piperazine was studied by a combination of metal extraction data, from batch experiments, and IR and XPS spectroscopic analysis of the metal loaded polymers. Extraction isotherms of gold cyanide show that gold binding is possible from 40–60 mg Au/g of resin in alkaline solutions, up to 150 mg Au/g of resin in acidic solutions. Efficient stripping of gold from the resin was achieved using ethanol/water solutions of sodium hydroxide, or 0.5 mol/l thiourea in sulfuric acid solutions.     

Structurally modified poly(vinyl alcohol) ionic composites as efficient humidity indicators

Synthesis of structurally modified poly(vinyl alcohol) (PVA) ionic composites is presented. Low‐molecular‐weight PVA (M_n = 18,000 g mol⁻¹) is prepared and blended together with either copper or borate ions under ambient conditions to yield PVA–Cu and PVA–B ionic composites, respectively. The borate ions coalesce together with different polymeric chains of PVA, forming a 3D network structure, which is identified by the weakening of  OH absorption in the infrared spectrum. On the other hand, copper ions yield a weakly crosslinked polyelectrolyte by forming a coordinated complex with the hydroxyl groups of PVA, which leads to an increase in the λ_max value in the ultraviolet–visible spectrum. The surface morphology of these PVA‐based ionic composites is studied via atomic force microscopy. Furthermore, the quantitative estimation of copper in PVA–Cu composites is performed by atomic absorption spectroscopy. Among these PVA ionic composites, the PVA–Cu exhibits excellent moisture absorption capability and dramatic changes in the color of thin composite film, when exposed to 75% humidity atmosphere. The absolute recovery, recyclability, and stability of the PVA–Cu ionic composites not only enable them to be good humidity indicators but the results show that these composites can be employed as efficient humidity‐sensitive material on suitable transducers for environmental and industrial applications. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Studies on the synthesis of low molecular weight,one‐dimensional polyanilines prepared by fast emulsion polymerization using (n‐dodecylbenzenesulfonic acid)/HCl emulsifiers

Low molecular weight polyaniline nanotubes were prepared by fast emulsion polymerization in the presence of both n‐dodecylbenzenesulfonic acid (DBSA) and HCl(aq). The anilinium monomers associated with DBSA emulsifiers were found to self‐arrange into strands of associated cylindrical micelles before polymerization, as monitored by their optical activity and optical image. In the presence of some HCl(aq), the monomer‐associated cylindrical micelles expanded and the polymerization rate could be speeded up. It was found that the low molecular weight (viscosity‐averaged molecular weight) polyaniline obtained can easily lead to the formation of highly conductive, one‐dimensional nanotubes or nanofibers monitored by the variation of optical activities and λ_max of the UV–visible–near IR spectra during polymerization. The DBSA/HCl ratio played an important role in the eventual properties and morphologies of the one‐dimensional polyanilines, which can be illustrated by conductivity, SEM and transmission electron microscopy measurements. The resultant one‐dimensional polyaniline nanotubes can be arranged into a layered structure by orientation, illustrated by AFM and wide‐angle X‐ray diffraction. © 2012 Society of Chemical Industry