Solvent Vapor‐Induced Nanowire Formation in Poly(3‐hexylthiophene) Thin Films

Summary: Nanowire lengths and length‐to‐width aspect ratios in regioregular poly(3‐hexylthiophene) (P3HT) were simply controlled through changes in the solvent vapor pressure during solidification. It is demonstrated that the nanowires grew by rod‐to‐rod association, in which the molecular long axis of the P3HT chains appeared to be well‐oriented parallel to the silicon substrate (Si/SiO_x). The formation of the nanowires took place by one dimensional self‐assembly, governed by π‐π stacking of the P3HT units.

TEM high contrast images showing P3HT nanowires fabricated by spin‐coating under a solvent vapor pressure.     

Electrochemical Determination of Dicofol at Nickel Nanowire Modified Poly(p‐aminophenol) Film Electrode

An electrochemical sensor was fabricated by construction of nickel nanowires on the surface of poly(p‐aminophenol) (PPAP) modified glassy carbon electrode. The electrochemical response of dicofol, a known pesticide and used for agricultural activities such as cyclic voltammetry and differential pulse voltammetry, were investigated and the results were compared with those obtained unmodified electrodes. Following the optimization of NaOH concentration, polymerization cycle number, Ni nanowire amount, the linear range for the dicofol was studied and found as 0.83–30.7 μmol L^?1 (R²=0.9981) at Ni/PPAP/GCE with a 0.08 μmol L^?1 detection limit according to S/N=3. Finally, the proposed Ni/PPAP/GCE sensor was successfully applied for the dicofol analysis in soil samples. The characterization of the developed surface was carried out by scanning electron microscopy and X‐Ray photoelectron spectroscopy.     

接枝共聚法制备二氧化钛/聚（苯乙烯-二乙烯基苯）复合微球

本文以KH560、苯乙烯、马来酸酐为连接组分,将二氧化钛接枝到聚（苯乙烯-二乙烯基苯）微球的表面,成功制备了无孔和多孔纳米复合微球。研究了硅烷偶联剂（KH560）和苯乙烯对二氧化钛在无孔微球表面的分散性和接枝数量以及支撑微球的多孔性质对接枝到微球内部的二氧化钛数量的影响。结果表明,KH560和苯乙烯能够提高二氧化钛在微球表面的分散性和稳定性,使二氧化钛以30-80nm的粒径接枝在微球表面。苯乙烯又能使二氧化钛在无孔微球表面的接枝数量从10.4%增大到20.4%。平均孔径为136nm的多孔微球为支撑微球得到的复合粒子中二氧化钛最高接枝量可达26%,明显高于无孔微球和平均孔径为31nm的多孔微球。     

Reduced Graphene Oxide/Poly(3‐hexylthiophene) Supramolecular Composites

Poly(3‐hexylthiophene) (P3HT) supramolecular structures are fabricated on P3HT‐dispersed reduced graphene oxide (RGO) monolayers and surfactant‐free RGO monolayers. P3HT is able to disperse RGO in hot anisole/N,N‐dimethylformamide solvents, and forms nanowires on RGO surfaces through a RGO induced crystallization process. The TEM and AFM investigation of the resultant P3HT/RGO composites shows that P3HT nanowires grow from RGO, and connect individual RGO monolayers. Raman spectroscopy confirms the interaction between P3HT and RGO, which allows the manipulation of the RGO electrical properties. Such a bottom‐up approach provides interesting graphene‐based composites for nanometer‐scale electronics.

     

Fe1/2Al1/2PO4催化1,2-二氯丙烷脱氯氧化制备环氧丙烷

Fe1/2Al1/2PO4催化1;2-二氯丙烷脱氯氧化制备环氧丙烷     

Simultaneous determination of ginsenoside Rg1, Re and notoginsenoside R1 in human plasma by LC‐MS/MS and its application in a pharmacokinetic study in Chinese volunteers

A rapid and sensitive liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method has been developed and validated for simultaneous quantification of ginsenosides Rg₁, Re and notoginsenoside R₁ in human plasma. Chromatography was performed on Capcell Pak C₁₈ MG II column using a binary gradient using mobile phase A (5 mm ammonium formate solution) and B (methanol, containing 5 mm ammonium formate) at a flow rate of 0.3 mL/min. The entire chromatographic run time was 3.2 min. Quantification was achieved using multiple reaction monitoring in positive mode using API 3000. This method was validated in terms of specificity, linearity, precision, accuracy, matrix effect and stability. The calibration curves were linear in the concentration range of 0.020–5.00 ng/mL for ginsenosides Rg₁, Re and notoginsenoside R₁. The lower limit of quantification (LLOQ) of this method was 0.020 ng/mL. The intra‐run and inter‐run precision values were within 12.31% for ginsenoside Rg₁, 14.13% for ginsenoside Re and 11.46% for notoginsenoside R₁ at their LLOQ levels. The samples were stable under all tested conditions. This method was successfully applied to study the pharmacokinetics of ginsenoside Rg₁ and notoginsenoside R₁ in 24 healthy volunteers following oral administration of 200 mg Sanqi Tongshu Enteric‐Pellets Capsule.     

Bottom‐up Assembly of Poly(3‐hexylthiophene) on Carbon Nanotubes: 2D Building Blocks for Nanoscale Circuits

Hierarchical poly(3‐hexylthiophene)(P3HT)/carbon nanotube (CNT) supramolecular structures were fabricated through a bottom‐up CNT induced P3HT crystallization strategy. P3HT nanowires growing perpendicular from CNT surface have uniform width and height. The density and the length of these nanowires can be controlled by tuning the P3HT/CNT mass ratio. The quasi‐isothermal crystallization process monitored by in situ UV–Vis spectroscopy indicates that CNTs can greatly enhance the P3HT crystallization, and the P3HT nanowire formation follows first‐order kinetics. Such bottom‐up strategy provides a general approach to build 2D functional conductive supramolecular structures that will lead to numerous applications in nanoscale electronics.

     

First‐Principles Calculations on Electronic Structures of N/V‐Doped and N‐V‐Dodoped Anatase TiO2 (101) Surfaces

The energetic and electronic properties of N/V‐doped and N‐V‐codoped anatase TiO₂ (101) surfaces are investigated by first‐principles calculations, with the aim to elucidate the relationship between the electronic structure and the photocatalytic performance of N‐V‐codoped TiO₂. Several substitutional and interstitial configurations for the N and/or V impurities in the bulk phase and on the surface are studied, and the relative stability of different doping configurations is compared by the impurity formation energy. Systematic calculations reveal that N and V impurities can be encapsulated by TiO₂ to form stable structures as a result of strong N‐V interactions both in the bulk and the surface model. Through analyzing and comparing the electronic structures of different doping systems, the synergistic doping effects are discussed in detail. Based on these discussions, we suggest that N_OV_Ti codoping cannot only narrow the band gap of anatase TiO₂, but also forms impurity states, which are propitious for the separation of photoexcited electron–hole pairs. In the case of N_OV_Ti‐codoped TiO₂ (101) surfaces, this phenomenon is especially prominent. Finally, a feasible synthesis route for N_OV_Ti codoping into anatase TiO₂ is proposed.     

Diiodobis(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)cadmium(II)

The Cd atom in Cd(Hmmi)₂I₂ is five‐coordinate with a trigonal bipyramidal geometry in which the apical sites are occupied by I and O atoms. Copyright © 2005 John Wiley & Sons, Ltd.     

µ2‐Diiodotetrakis(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)dicadmium(II) bis[triiodo(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)cadmate(II)] dihydrate

There are two types of Cd in the title compound, the six‐coordinated Cd atom in the cation is in a distorted octahedral geometry while the four‐coordinated Cd in the anion shows a distorted tetrahedral geometry. Copyright © 2005 John Wiley & Sons, Ltd.     

Poly(l‐Lactic Acid)/Gelatin Fibrous Scaffold Loaded with Simvastatin/Beta‐Cyclodextrin‐Modified Hydroxyapatite Inclusion Complex for Bone Tissue Regeneration

Recently, the application of nanostructured materials in the field of tissue engineering has garnered attention to mediate treatment and regeneration of bone defects. In this study, poly(l ‐lactic acid) (PLLA)/gelatin (PG) fibrous scaffolds are fabricated and β‐cyclodextrin (βCD) grafted nano‐hydroxyapatite (HAp) is coated onto the fibrous scaffold surface via an interaction between βCD and adamantane. Simvastatin (SIM), which is known to promote osteoblast viability and differentiation, is loaded into the remaining βCD. The specimen morphologies are characterized by scanning electron microscopy. The release profile of SIM from the drug loaded scaffold is also evaluated. In vitro proliferation and osteogenic differentiation of human adipose derived stem cells on SIM/HAp coated PG composite scaffolds is characterized by alkaline phosphatase (ALP) activity, mineralization (Alizarin Red S staining), and real time Polymerase chain reaction (PCR). The scaffolds are then implanted into rabbit calvarial defects and analyzed by microcomputed tomography for bone formation after four and eight weeks. These results demonstrate that SIM loaded PLLA/gelatin/HAp‐(βCD) scaffolds promote significantly higher ALP activity, mineralization, osteogenic gene expression, and bone regeneration than control scaffolds. This suggests the potential application of this material toward bone tissue engineering.

     

Higher α‐olefin polymerizations catalyzed by rac‐Me2Si(1‐C5H2‐2‐CH3‐4‐tBu)2Zr(NMe2)2/Al(iBu)3/[Ph3C][B(C6F5)4]

Polymerizations of higher α‐olefins, 1‐pentene, 1‐hexene, 1‐octene, and 1‐decene were carried out at 30 °C in toluene by using highly isospecific rac‐Me₂Si(1‐C₅H₂‐2‐CH₃‐4‐^t Bu)₂Zr(NMe₂)₂ (rac‐1) compound in the presence of Al(iBu)₃/[CPh₃][B(C₆F₅)₄] as a cocatalyst formulation. Both the bulkiness of monomer and the lateral size of polymer influenced the activity of polymerization. The larger lateral of polymer chain opens the π‐ligand of active site wide and favors the insertion of monomer, while the large size of monomer inserts itself into polymer chain more difficultly due to the steric hindrance. Highly isotactic poly(α‐olefin)s of high molecular weight (MW) were produced. The MW decreased from polypropylene to poly(1‐hexene), and then increased from poly(1‐hexene) to poly(1‐decene). The isotacticity (as [mm] triad) of the polymer decreased with the increased lateral size in the order: poly(1‐pentene) > poly(1‐hexene) > poly(1‐octene) > poly(1‐decene). The similar dependence of the lateral size on the melting point of polymer was recorded by differential scanning calorimetry (DSC). ¹H NMR analysis showed that vinylidene group resulting from β‐H elimination and saturated methyl groups resulting from chain transfer to cocatalyst are the main end groups of polymer chain. The vinylidene and internal double bonds are also identified by Raman spectroscopy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1687–1697, 2000     

TGF‐β1‐Modified Hyaluronic Acid/Poly(glycidol) Hydrogels for Chondrogenic Differentiation of Human Mesenchymal Stromal Cells

In cartilage regeneration, the biomimetic functionalization of hydrogels with growth factors is a promising approach to improve the in vivo performance and furthermore the clinical potential of these materials. In order to achieve this without compromising network properties, multifunctional linear poly(glycidol) acrylate (PG‐Acr) is synthesized and utilized as crosslinker for hydrogel formation with thiol‐functionalized hyaluronic acid via Michael‐type addition. As proof‐of‐principle for a bioactivation, transforming growth factor‐beta 1 (TGF‐β1) is covalently bound to PG‐Acr via Traut's reagent which does not compromise the hydrogel gelation and swelling behavior. Human mesenchymal stromal cells (MSCs) embedded within these bioactive hydrogels show a distinct dose‐dependent chondrogenesis. Covalent incorporation of TGF‐β1 significantly enhances the chondrogenic differentiation of MSCs compared to hydrogels with supplemented noncovalently bound TGF‐β1. The observed chondrogenic response is similar to standard cell culture with TGF‐β1 addition with each medium change. In general, multifunctional PG‐Acr offers the opportunity to introduce a range of biomimetic modifications (peptides, growth factors) into hydrogels and, thus, appears as an attractive potential material for various applications in regenerative medicine.     

Nanocomposites of Polyaniline/Poly(2‐methoxyaniline‐5‐sulfonic acid)

Summary: Poly(2‐methoxyaniline‐5‐sulfonic acid) (PMAS) is a water‐soluble derivative of polyaniline that carries negatively charged sulfonate groups. This self‐doped conducting polymer also behaves like a polyelectrolyte that can subsequently function as a dopant in polyaniline (PAn). The chemical synthesis of PAn/PMAS is presented describing the preparation of a highly stable composite dispersion. TEM images reveal a mixture of well‐defined nanofibres and nanoparticles with diameters between 20 and 100 nm. The UV‐vis spectra of the PAn/PMAS composite in water and in alkaline media indicate that both PAn and PMAS are present in the composite. Electrochemical studies show that both of the conducting polymer components are capable of undergoing oxidation and reduction. The novel PAn/PMAS nanocomposite has enhanced electrical conductivity and stability compared to PAn/HCl nanofibres prepared under equivalent conditions, making it a promising material for applications in areas such as batteries, electronic textiles, electrochromics, and chemical sensors.

Transmission electron micrograph of a PAn/PMAS nanocomposite.     

Poly(phenyl methacrylate) and poly(1‐naphthyl methacrylate) prepared in microemulsions

Phenyl methacrylate and 1‐naphthyl methacrylate were polymerized in microemulsions using stearyltrimethylammonium chloride, cetyltrimethylammonium bromide, and a mixture of nonionic Triton surfactants to form latexes that were 20–30 nm in diameter. A temperature of 70 °C was needed to obtain polymers using thermal initiation. The tacticities of poly(phenyl methacrylate) (PPhMA) (55% rr) and poly(1‐naphthyl methacrylate) (P‐1‐NM) (47% rr) were the same as those of the polymers prepared in toluene solutions. The weight average molecular weights were 1 × 10⁶ and 5 × 10⁵ g/mol for PPhMA and P‐1‐NM prepared in microemulsions with very broad distributions. PPhMA samples from microemulsions and solution had the same T_g = 127 °C. P‐1‐NM from microemulsions had T_g = 145–147 °C compared with T_g = 142 °C for P‐1‐NM from solution. The molecular weights and the glass‐transition temperatures of both PPhMA and P‐1‐NM from microemulsions are substantially higher than any previously reported. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 519–524, 2001     

A New Type of Thermoresponsive Copolymer with UCST‐Type Transitions in Water: Poly(N‐vinylimidazole‐co‐1‐vinyl‐2‐(hydroxymethyl)imidazole)

1‐Vinyl‐2‐(hydroxymethyl)imidazole ( 2 ) is synthesized by a procedure described in the literature. Corresponding copolymers with upper critical solution temperature (UCST)‐type transitions in water and high‐glass transition temperatures (T_g) are prepared by free radical copolymerization with N‐vinylimidazole ( 1 ). Depending on the copolymer composition, the cloud point can be varied between 19 and 41 °C. As the copolymer composition is identical with the monomer feed ratio, the cloud point can be easily tuned in the desired range. Furthermore, a distinctive pH‐dependence and salt effect can be observed.