Hyperbranched polymer-assisted hydrothermal in situ synthesis of submicrometer silver tubes

We produced silver tubes with an outer diameter of 1 mu m, wall thickness of 200 nm, and length of hundreds of micrometers by hydrothermal treatment of aqueous solutions of AgNO3 and hyperbranched polyglycidol (HPG) at 165 degrees C. The surfaces of the silver tubes were chemically modified by HPG, which was confirmed by FTIR of the silver tubes.

A novel approach to synthesis of functional CPVC and CPE or graft copolymers - in situ chlorinating graft

A new process of graft copolymerization of poly(vinyl chloride) (PVC) and polyethylene (PE) with other monomers was developed. The grafted chlorinated poly(vinyl chloride) (CPVC) and chlorinated polyethylene (CPE) were synthesized by in situ chlorinating graft copolymerization (ISCGC) and were characterized. Convincing evidence for grafting and the structure of graft copolymers was obtained using FT-IR, H-1-NMR, gel permeation chromatography (GPC), and the vulcanized curves. Their mechanical properties were also measured. The results show that the products have different molecular structure from those prepared by other conventional graft processes. Their graft chains are short, being highly branched and chlorinated. The graft copolymers have no crosslinking structure. The unique molecular structure will make the materials equipped with special properties.

In situ circular dichroic electrochemical study of bilirubin and bovine serum albumin complex

The electrooxidation of bilirubin (BR) and bovine serum albumin (BSA) complexes was studied by in situ circular dichroism (CD) spectroelectrochemistry. The result showed that the mechanism of the whole electrooxidation process of this complex corresponded to electrochemical processes (EE mechanism) in aqueous solution. Some parameters of the process were obtained by double logarithm method, differential method and nonlinear regression method. In visible region, CD spectra of the two enantiomeric components of the complex and their fraction distribution against applied potentials were obtained by singular value decomposition least-square (SVDLS) method. Meanwhile, the distribution of the five components of secondary structure was also obtained by the same method in far-UV region. The peak potential gotten from EE mechanism corresponds to a turning point for the component transition, beyond which the whole reaction reaches a new equilibrium. Under applied positive potentials, the enantiomeric equilibrium between M and P form is broken and M form transfers to its enantiomer of P, while the fraction of alpha-helix increases and that improves the transition to P form.

Surface modification of single-walled carbon nanotubes with polyethylene via in situ Ziegler-Natta polymerization

Single-walled carbon nanotubes (SWNTs) were modified with polyethylene (PE) prepared by in situ Ziegler-Natta polymerization. Because of the catalyst pre-treated on the surface of the SWNTs, the ethylene was expected to polymerize there. Scanning electron microscopy images and solubility measurements showed that the surface of the SWNTs was covered with a PE layer, and a crosslink may have formed between the SWNTs and PE. When the SWNTs covered with a PE layer were mixed with commercialized PE by melt blending, the resulting composite had better mechanical properties than the composite from the SWNTs without a PE layer. The yield strength, the tensile strength and modulus, the strain at break, and the fracture energy of the modified-SWNT/PE composites were improved by 25, 15.2, 25.4, 21, and 38% in comparison with those of the raw-SWNT/PE composites.

Preparation and luminescence properties of in situ formed lanthanide complexes covalently grafted to a silica network

Lanthanide-doped sol-gel-derived materials are an attractive type of luminescent materials that can be processed at ambient temperatures. However, the solubility of the lanthanide complexes in the matrix is a problem and it is difficult to obtain a uniform distribution of the complexes. Fortunately, these problems can be solved by covalently linking the lanthanide complex to the sol-gel-derived matrix. In this study, luminescent Eu3+ and Tb3+ bipyridine complexes were immobilized on sol-gel-derived silica. FT-IR, DTA-TG and luminescence spectra, as well as luminescence decay analysis, were used to characterize the obtained hybrid materials. The organic groups from the bipyridine-Si moiety were mostly destroyed between 220 and 600 degreesC. The luminescence properties of lanthanide bipyridine complexes anchored to the backbone of the silica network and the corresponding pure complexes were comparatively investigated, which indicates that the lanthanide bipyridine complex was formed during the hydrolysis and co-condensation of TEOS and modified bipyridine. Excitation at the ligand absorption wavelength (336 nm for the hybrid materials and 350 nm for the pure complexes) resulted in strong emission of the lanthanide ions: Eu3+ D-5(0)-F-7(J) (J = 0, 1, 2, 3, 4) and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) emission lines due to efficient energy transfer from the ligands to the lanthanide ions.

In situ electrochemical SERS studies on electrodeposition of aniline on 4-ATP/Au surface

The electrochemical polymerization of 0.01 M aniline in 1 M H2SO4 aqueous solution on roughened Au surface modified with a self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) has been investigated by in situ electrochemical surface-enhanced Raman scattering spectroscopy (SERS). The repeat units and possible structures of the electrodeposited polyaniline (PANI) film were proposed; i.e., aniline monomer is coupled in head-to-tail predominately at the C-4 of aniline and amine of 4-ATP, and the thin PANI film is orientated vertically to substrate surface. Simultaneous Raman spectra during potential scanning indicate clearly that the ultrathin PANI film (in initial growth of the film) consists of semiquinone radical cation (IP+), para-disubstituted benzene (IP and IP+) and quinine diimine (NP) while it is oxidized, and without quinine diimine and semiquinone radical cation while reduced. Meanwhile, the results confirm that 4-ATP monolayer shows a strong promotion on the electrodeposition of aniline monomer, and a possible polymerization mechanism was proposed.

Self-assembled monolayer of polyoxometalate on gold surfaces: Quartz crystal microbalance, electrochemistry, and in-situ scanning tunneling microscopy study

A new kind of inorganic self-assembled monolayer (SAM) was prepared by spontaneous adsorption of polyoxometalate anion, AsMo11VO404-, onto a gold surface from acidic aqueous solution. The adsorption process, structure, and electrochemical properties of the AsMo11VO404- SAM were investigated by quartz crystal microbalance (QCM), electrochemistry, and scanning tunneling microscopy (STM). The QCM data suggested that the self-assembling process could be described in terms of the Langmuir adsorption model, providing the value of the free energy of adsorption at -20 KJ mol(-1). The maximum surface coverage of the AsMo11VO404- SAM on gold surface was determined from the QCM data to be 1.7 x 10(-10) mol cm(-2), corresponding to a close-packed monolayer of AsMo11VO404- anion. The analysis of the voltammograms of the AsMo11VO404- SAM on gold electrode showed three pairs of reversible peaks with an equal surface coverage of 1.78 x 10(-10) mol cm(-2) for each of the peaks, and the value was agreed well with the QCM data. In-situ STM image demonstrated that the AsMo11VO404- SAM was very uniform and no aggregates or multilayer could be observed. Furthermore, the high-resolution STM images revealed that the AsMo11VO404- SAM on Au(lll) surface was composed of square unit cells with a lattice space of 10-11 Angstrom at +0.7 V (vs Ag\AgCl). The value was quite close to the diameter of AsMo11VO404- anion obtained from X-ray crystallographic study. The surface coverage of the AsMo11VO404- SAM on gold electrode estimated from the STM image was around 1.8 x 10(-10) mol cm(-2), which was consistent with the QCM and electrochemical results.

In-situ FTIR spectroelectrochemical study of chromium hexacyanoferrate on glassy carbon electrode

Chromium hexacyanoferrate (CrHCF) modified grassy carbon electrode (GC) in different electrolytes was studied by cyclic voltammetry and in situ FTIR spectroelectrochemistry. The results indicate that the behavior of CrHCF firm can be understood in term of two structures: Cr1/3Cr(III)Fe(II)(CN), and MCr(III)Fe(II)(CN)(6). Besides,the film exists in amorphous state: the outer layer is porous film, while the inner layer is relatively compact. According to the electrochemical reaction of CrHCF, the lattice can contract and expand with the cations' diffusion.

In situ UV-vis and CD thin-layer spectroelectrochemistry study of the electrochemical behavior of L-noradrenaline in alkaline solution

Electrochemical redox behavior of noradrenaline in alkaline solution on a glassy carbon electrode has been investigated by in situ UV-vis and CD spectroelectrochemistry by using a long optical path thin-layer cell. The experimental data were processed by using a double logarithmic method of analysis together with nonlinear regression which confirmed that the first step in both the oxidation of noradrenaline and reduction of noradrenochrome is a two-electron irreversible process governed by an EE mechanism. The kinetic parameters of the electrode reactions, i.e., charge transfer coefficient and the number of electrons transferred, alpha(1)n(1) = 0.11 and alpha(2)n(2) = 0.23, formal potentials modified with kinetics, E-1(0') = 0.65 (+/- 0.01) V and E-2(0') = 0.72V and standard rate cnstants, k(1)(0) = 7.0(+/-0.5)x10(-5) cm s(-1), for the first and second steps in the oxidation process of noradrenaline, and similarly, alpha(1)n(1) = 0.33, alpha(2)n(2) = 0.58, E-1(0') = 0.37(+/-0.01) V, E-0' = -0.25 (+/-0.01) V and k(1)(0) approximate to k(2)(0) = 1.06 (+/-0.05)x10(-4) cm s(-1) for the first and second steps in the reduction process of noradrenochrome were also determined.

A novel in-situ spectroelectrochemical technique with probe beam deflection: For study of the ion exchange between films on electrode surface and solutions

A novel in-situ spectroelectrochemical technique, the combination of probe beam deflection (PBD) with cyclic voltammetry (CV), was used to study the ion exchange process of prussian blue(PB) modified film electrode in contact with various electrolyte solutions. The ion exchange mechanism was verified as following: (K2Fe2+FeII)(CN)(6) -e(-)-k(+)reversible arrow +e(-)+k(+) (KFe3+FeII)(CN)(6) -ke(-)-xk(+)reversible arrow +xe(-)+kk(+) [(Fe3+FeIII)(CN)(6)](x)[(KFe3+FeII)(CN)(6)](1-x) where on reduction PB film in contact with an acidic KCl electrolyte, it was confirmed that protons enter into the PB film before K+ cations.

IN-SITU UV-VISIBLE SPECTROELECTROCHEMICAL AND CIRCULAR DICHROIC ELECTROCHEMICAL STUDY OF BILIRUBIN AND BILIRUBIN PLUS HUMAN SERUM-ALBUMIN COMPLEX

The electro-oxidation of bilirubin (BR) in aqueous solution was investigated by cyclic voltammetry and in-situ thin-layer spectroelectrochemical techniques, It was found that both oxidation processes of BR are two electron transfer reactions. A mechanism

INVESTIGATION OF THE ELECTROCHEMICAL-BEHAVIOR OF TRYPTOPHAN BY IN-SITU CIRCULAR DICHROIC SPECTROELECTROCHEMISTRY

The electrochemical redox processes of tryptophan were studied by in situ circular dichroic (CD) spectroelectrochemistry with a long optical path length thin-layer cell. The oxidation of tryptophan at low concentrations in basic aqueous solution is a two-electron irreversible electrochemical process which results from an irreversible subsequent chemical reaction. A method of treatment of CD spectral data for the irreversible electrochemical reaction is suggested, from which the values E(p/2) = 0.46 V, alphan(alpha) = 0.313 and k0 = 2.4 x 10(-4) cm s-1 (the standard heterogeneous reaction rate constant for tryptophan oxidation) were obtained.

Microstructure and wear resistance of in situ TiCp composite coating by laser cladding

A new in situ method was realized by one step laser cladding to produce Ni-base alloy composite coating reinforced by in situ reacted and gradiently distributed TiCp particles. The submicron TiCp particles were formed and uniformly distributed because of the in situ reaction and trapping effect under the rapid solidification condition. And, TiCp particles were of gradient distribution on a macro scale and their volume fraction increased from 1.86% at the layer/substrate interface to a maximum 38.4% at the surface of the layer. Furthermore, the in situ generated TiCp/gamma-Ni interfaces were free from deleterious surface reactions. Additionally, the clad coating also revealed a high microhardness of gradient variation with the layer depth and the superior abrasive wear resistance.

Laser Melted TiC Reinforced Nickel Aluminide Matrix in situ Composites

Titanium carbide reinforced nickel aluminide matrix in situ composites were produced using a newly patented laser melting furnace. Microstructure of the laser melted TiC/(Ni3Al–NiAl) in situ composites was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results showed that the constituent phases in the laser melted in situ composites are TiC, Ni3Al and NiAl. Volume fraction of TiC and NiAl increase with increasing content of titanium and carbon. The growth morphology of the reinforcing TiC carbide has typically faceted features, indicating that the lateral growth mechanism is still predominant growth mode under rapid.

Adlayer Structures of DL-Homocysteine and L-Homocysteine Thiolactone on Au(111) Surface: an in situ STM Study

The adsorption Of DL-homocysteine (Hcy) and L-homocysteine thiolactone (HTL) on Au(1 1 1) electrode was investigated in 0.1 M HClO4 by cyclic voltammetry and in situ scanning tunneling microscopy (STM). Hcy and HTL molecules formed highly ordered adlayers on Au(1 1 1) surface. High-resolution STM images revealed the orientation and packing arrangement in the ordered adlayers. Hcy molecules formed (2root3 x 3root3)R30degrees adlayer structure and H-bonds between carboxyl groups were assumed to be responsible for the origin of tail-to-tail or head-to-head molecular arrangement, while HTL molecules formed (4 x 6) adlayer structure, and two different orientations and appearances in the ordered adlayer were found. Structural models were proposed for the two adlayers.