Electrochemically polymerized 2,2-dimethyl-3,4-propylenedioxythiophene on carbon fiber for microsupercapacitor

ProDOT(Me)₂ was electrochemically polymerized onto a carbon fiber microelectrode (CFME) by cyclovoltammetry under a wide potential range (0–1.6 V) with well-defined parameters. The nano to micron scale coatings on CFMEs were characterized by cyclovoltammetry, ex situ FTIR attenuated total reflectance spectroscopy (FTIR-ATR), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM and EDX). The existence of a capacitance behavior is shown by Nyquist, Bode phase relationship.     

Physical and electrochemical characterization of nanocomposites formed from polythiophene and titaniumdioxide

A simple method for covering titanium dioxide particles with a polythiophene film by chemical preparation was developed. The resulting nanocomposites consisted of a titanium dioxide core with a grain size of 25-250 nm and a polythiophene shell between 1 and 2 nm thickness. The composites were characterized by scanning electron microscopy, thermogravimetry, X-ray photoelectron spectroscopy, cyclovoltammetry, impedance spectroscopy and photocurrent spectroscopy. The content of polythiophene in the composite (determined by thermogravimetry), was between 2% and 5%. Disk-like electrodes were prepared by pressing and then characterized by various electrochemical methods. A reversible redox potential of the polythiophene of +1.0 V (NHE) was determined by cyclic voltammetry. The reduced form of polythiophene behaved as a p-type semiconductor so that the composite with n-type TiO₂ contained the properties of a p/n-junction. In the photocurrent spectra (depending on the applied potential), the characteristic anodic peaks of the TiO₂ at λ=320 nm and cathodic peaks of the polythiophene around λ=500 nm were found. A new cathodic peak observed at 370 nm was explained as a new feature of the pn interface.     

Preparation and characterization of platinum-ruthenium bimetallic nanoparticles using reverse microemulsions for fuel cell catalyst

Platinum-ruthenium bimetallic nanoparticles are prepared by chemical reduction using sodium borohydride in reverse microemulsions of water/isooctane/Igepal CA-630/2-propanol for fuel cell catalysts. The prepared nanoparticles are characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray analysis. The average size and morphology of nanoparticles are dependent on the water volume fraction in reverse microemulsion system in the range of ca. 2-4 nm. The morphology of particles is related with the percolation behavior of water droplets in reverse microemulsions. By the pretreatment of water phase using a hydrochloric acid, the particles of a homogeneous solid solution state can be obtained. The CO stripping cyclovoltammetry and the electrochemical measurements compared with commercial catalyst show that the prepared particles have a high electrochemically active surface area and a stable and high catalytic activity for reformate gas oxidation.     

Potential-induced lifting of the Au(1 0 0)-surface reconstruction studied with DFT

The potential-induced surface reconstruction of Au(1 0 0) was studied by a combination of density functional theory (DFT) and thermodynamic considerations. On the basis of realistic models for the reconstructed surface ((5 × 1) and (7 × 1) unitcells), in which a hexagonal overlayer was located above the bulk-truncated Au(1 0 0) surface, we found that applying an electric field causes a slight lifting of the overlayer, leading to a stronger surface buckling than without electric field. Using experimental cyclovoltammetry measurements we were able to relate the electric field applied in our calculations to the electrode potential. The resulting surface free energy curves showed a transition from the hexagonal-reconstructed surface phase to the non-reconstructed structure between +0.5 and +0.6 V (versus SCE-electrode) depending on the ion concentration in the electrolyte. Higher potentials values are required at lower electrolyte concentrations.     

The First Anionic Thia‐Fries Rearrangements at Ferrocene: Ready Access to Trifluoromethylsulfonyl‐Substituted Hydroxyferrocenes and an Extremely High Interannular Stereoinduction between Cyclopentadienyl Ligands

Attempts originally directed towards the generation of ferrocyne (1,2‐dehydroferrocene, 4 ) and ferrocenediyne (1,2,1′,2′‐tetradehydroferrocene, 5 ) by triflate elimination from the respective ferrocenyl triflates led to the discovery of the first anionic thia‐Fries rearrangements at a five‐membered ring. These reactions take place with remarkable efficiency under very mild reaction conditions and yield the respective trifluoromethylsulfonyl‐substituted ferrocenols. Most remarkably, the reaction starting from 1,1′‐ferrocenediyl ditriflate ( 9 ) adopts an extremely high interannular stereoinduction in that exclusively the meso rearrangement product, meso‐2,2′‐bis(trifluoromethylsulfonyl)‐1,1′‐ferrocenediol ( 16 ), is formed, the corresponding racemic product 17 is not observed. It is shown that the second anionic thia‐Fries rearrangement proceeds at a much larger rate than the first one. The stereochemistry and the high rate of this reaction are explained on the basis of electronic as well as steric considerations. The redox behavior of some of the unprecedented ferrocene derivatives has been characterized by cyclovoltammetry.     

Ultra thin layers as new concepts for corrosion inhibition and adhesion promotion

The adsorption and self-organization process as well as the surface reactions of several bifunctional adhesion promoters on different oxide surfaces have been investigated. The aim was to improve the adhesion between metal oxides and different organic coatings. We developed a large number of bifunctional compounds, which are able to adsorb spontaneously on different pre-treated metal (oxide) surfaces. The second group can be designed for grafting different otherwise incompatible layers.

Therefore, a special two-step procedure has been developed: (1) adsorption of the designed bifunctional molecules on the substrate and (2) surface reaction of the terminal reactive group with a polymeric top coating or with further monomers resulting in a strongly bond composite.

For this purpose substances were chosen having a surface reactive group, an aliphatic spacer and a reactive group for a suitable top layer. Phosphonic acids forming strong bonds with several metal surfaces were chosen as surface-active groups on metal oxide substrates.

The termination of these compounds with further reactive groups opened a wide range of possible applications. Functionalities like amino or carboxylic groups allowed reactions with commercial lacquers (e.g., polyurethane) for improving adhesion promotion and corrosion inhibition of the metal substrates. By using polymerizable groups like thiophene and pyrrole an in situ surface polymerization with further monomers is possible directly on the substrate.

The adsorbed films of bifunctional phosphonic acids on metal (oxide) substrates were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS), the surface polymerized films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), cyclovoltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results showed that monolayers were formed, which were correctly oriented on the surfaces: the phosphonic acid group was attached to the substrate whereas the terminal group was free standing for further reactions. Surface polymerization with additional monomer was possible either chemically or electrochemically resulting in smooth polymer layers of adjustable thickness. The conducting polymers were found to be p-conductive with a doping level of about 30%. Conductivity measurements revealed a conductivity of about 0.13 S/cm for the best films.

Based on this principle two possible applications are given: firstly, a corrosion protecting system for steel, and secondly, a model release system for protecting steel after damage of the coating.     

Formation of ultra-thin amorphous conversion films on zinc alloy coatings: Part 1. Composition and reactivity of native oxides on ZnAl (0.05%) coatings

Within the two parts of this contribution a detailed investigation of the nucleation and growth of ultra-thin amorphous conversion coatings on hot dip galvanised steel is reported. The first part deals with the composition and reactivity of the native ultra-thin oxyhydroxide films that are formed on the zinc alloy surface during the hot dip galvanising process due to the enrichment of aluminium at the outer surface of the alloy coating. Complimentary surface analytical techniques such as FT-IR-spectroscopy at grazing incidence and X-ray photo electron spectroscopy, high resolution AFM on selected grains to study the surface topography and cyclovoltammetry as well as quasi stationary current potential curves and Kelvin probe measurements to study surface ion and electron transfer reactions were applied. Changes in the chemical composition, the electronic properties and the morphology of the ultra-thin surface could thereby be analysed. The surface of the ZnAl alloy is composed of an about 3-4 nm thick mixed Zn and Al-oxyhydroxide layer with Zn-oxyhydroxide slightly enriched at the outermost surface. This mixed oxyhydroxide causes to a significant inhibition of electron transfer reactions. During alkaline cleaning the surface is nanoscopically roughened and the mixed oxyhydroxide is converted into an electro-conducting hydroxyl rich pure Zn-oxyhydroxide layer with a thickness of about 4 nm. In the second part of this paper the effect of the inorganic surface layer on the film formation is correlated with these findings.     

Sputtered iridium oxide films as electrocatalysts for water splitting via PEM electrolysis

Thin films of iridium oxide deposited by reactive magnetron sputtering have been investigated as catalysts for electrochemical water splitting in a polymer electrolyte membrane (PEM) cell. The sputtered films possess excellent mechanical stability and corrosion resistance at the high anodic potentials where oxygen evolution takes place. Their catalytic activity has been assessed using the conventional electrochemical methods of cyclovoltammetry and steady state polarisation techniques. A morphology factor assessing the catalyst active surface for a series of sputtered samples with varying thickness/loading has been determined and correlated to the catalytic efficiency. It has been proven that iridium oxide is a very efficient catalyst for oxygen evolution reaction (OER). The best performance with anodic current density of 0.3 A cm⁻² at potential of 1.55 V (versus RHE) has shown the 500 nm thick film containing 0.2 mg cm⁻² catalyst. The results obtained have also demonstrated the advantages of the reactive magnetron sputtering as simple and reliable method for deposition of efficient and cost effective catalysts for PEM electrolysis application.     

Synthesis and characterization of chemically and electrochemically prepared conducting polymer/iron oxalate composites

Poly(3-octyl-thiophene) (POT) and polypyrrole (PPy) iron oxalate composites were synthesized through a post-polymerization oxidative treatment. The composite of the latter has been prepared also by electrochemical polymerization. The samples have been characterized by X-ray diffraction (XRD), impedance spectroscopy, scanning electron microscope (SEM) combined with energy dispersive X-ray (EDX) spectroscopy, Mössbauer spectroscopy, cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). In case of PPy, two peaks in the XRD spectra show the presence of iron containing composite, while with POT only the layered structure originating from the octyl side-chain interactions was modified by the composite formation. The assumption of the weakening of short- and long-range interactions was proven by the decrease in conductivity of the composite. The successful electrochemical synthesis resulted a composite of ∼5% iron content, determined by EDX. Mössbauer spectroscopy measurements evidenced a composite containing mixed valence iron oxalate doping ions, which supports the indirect EQCM data.     

Synthesis and characterization of the novel block copolymer poly(ε‐caprolactone)‐b‐poly(4‐vinyl pyridine) by the combination of coordination and controlled free‐radical polymerizations

A novel block copolymer, poly(ε‐caprolactone)‐b‐poly(4‐vinyl pyridine), was synthesized with a bifunctional initiator strategy. Poly(ε‐caprolactone) prepolymer with a 2,2,6,6‐tetramethylpiperidinyloxy (TEMPO) end group (PCL_T) was first obtained by coordination polymerization, which showed a controlled mechanism in the process. By means of ultraviolet spectroscopy and electron spin resonance spectroscopy, the TEMPO moiety was determined to be intact in the polymerization. The copolymers were then obtained by the controlled radical polymerization of 4‐vinyl pyridine in the presence of PCL_T. The desired block copolymers were characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, and NMR spectroscopy in detail. Also, the effects of the molecular weight and concentration of PCL_T on the copolymerization were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2280–2285, 2004     

Synthesis of electroactive tetraaniline-based acrylic polyol by atom transfer radical polymerization for anticorrosive coating application

In this work, block copolymers of butyl acrylate and glycidyl methacrylate (GMA) having molecular weights 10,000 Da were synthesized with varied GMA block lengths by 10%, 20%, and 30% using atom transfer radical polymerization. The synthesized copolymers were further reacted with tetraaniline to formulate conductive polyol and further characterized by mass spectroscopy, UV–visible spectroscopy, ¹HNMR, and FTIR. The block copolymers formed were evaluated by gel permeation chromatography, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, and nuclear magnetic resonance (NMR) techniques for structural elucidation. These polyols were formed with 10, 20, and 30 wt% with isocyanate (HDI N-3300) to form a polyurethane. The effect of concentration of conducting polyol on anticorrosive coating performance properties, namely mechanical and optical properties, was further studied. The anticorrosive performance was evaluated by salt spray test and electrochemical impedance spectroscopy.     

NMR, multi-spectroscopic and molecular modeling approach to investigate the complexes between C.I. Acid Orange 7 and human serum albumin in vitro

In this study, the interaction between C.I. Acid Orange 7 (AO7) and human serum albumin (HSA) was firstly investigated using nuclear magnetic resonance (NMR) spectroscopy in combination with fluorescence quenching spectroscopy, three-dimensional fluorescence spectroscopy, UV-vis absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy and molecular modeling method in vitro. The results of NMR data confirmed that AO7 indeed interacted with HSA, and the hydrophobic portion of AO7 should be embedded to the hydrophobic pocket of HSA. The fluorescence quenching analysis revealed that AO7 can bind to HSA. The conformational change of HSA in the presence of AO7 was confirmed by synchronous fluorescence, three-dimensional fluorescence, UV-vis absorption, FT-IR and CD spectra. The binding distance between AO7 and tryptophan residue of HSA was calculated by the efficiency of fluorescence resonance energy transfer. Molecular modeling showed that hydrophobic force and hydrogen bonds were the major interaction between AO7 and HSA.     

Functionalization of reduced graphene oxide nanosheets via stacking interactions with the fluorescent and water-soluble perylene bisimide-containing polymers

Reduced graphene oxide (RGO)-polymer composites were prepared via π-π stacking interactions of RGO with the perylene bisimide-containing poly(glyceryl acrylate) (PBIPGA). PBIPGA was synthesized via atom transfer radical polymerization (ATRP) of solketal acrylate (SA), using bifunctional N,N′-bis{2-[2-[(2-bromo-2-methylpropanoyl)oxy]ethoxy]ethyl}perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI-Br) as the initiator, and subsequent hydrolysis of the acetal-protecting group. PBIPGA was characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV-visible absorption spectroscopy and fluorescence spectroscopy. The presence of π-π stacking interactions between PBI and the RGO surface was suggested by fluorescence and UV-visible absorption spectroscopy results. The chemical states and π-π stacking interaction, morphology, and composition of RGO-PBIPGA composites were characterized, respectively, by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The low cytotoxicity level of the RGO-PBIPGA composites was revealed by incubation with 3T3 fibroblasts in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays in vitro.     

Polyimide nanohybrid films with electrochemically functionalized graphene

Graphite was functionalized electrochemically in a potassium fluoride solution and used to prepare polyimide (PI)/graphene nanohybrid films. The as‐made electrochemically fluorinated graphene (EFG) was used to prepare nanohybrid films with colorless PI, which was synthesized from 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride and bis(trifluoromethyl) benzidine by in situ polymerization. The surface functionalization of graphite was characterized by powder XRD, TEM with energy dispersive X‐ray spectroscopy elemental mapping, X‐ray photoelectron spectroscopy, Raman spectroscopy, and TGA. The microstructure of the films was characterized by Fourier transform IR spectroscopy, XRD and SEM. The film properties were measured using a universal testing machine, TGA, dynamic mechanical analysis, four‐point probe, UV–visible spectroscopy and water contact angle analysis. EFG improved the tensile strength and modulus of the nanohybrid films by 20% and 50%, respectively. The glass transition temperature and electrical conductivity of the nanohybrid films were 12 °C and nine orders of magnitude higher than those of the neat PI film, respectively. The nanohybrid film maintained 80% optical transmittance even after the addition of 0.1 wt% EFG. © 2019 Society of Chemical Industry     

Biofabrication of gold nanoparticles and its biocompatibility in human breast adenocarcinoma cells (MCF-7)

In this paper, a simple and environmentally friendly method for synthesis of gold nanoparticles (AuNPs) using culture supernatant of Bacillus flexus as reductants and stabilizers is reported. The prepared AuNPs were characterized by various analytical techniques. UV–visible spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) results confirmed that Au³⁺ ions reduced into Au⁰. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements confirmed that the chemical surface structure of AuNPs. TEM images showed the size and morphology of AuNPs. Moreover, the toxicity studies suggested that AuNPs were neither toxic nor inhibitory to human breast cancer cells (MCF-7).     

Spectroscopy and spectrometry of lipids — Part 1

For a collection of articles on spectroscopy and spectrometry of lipids to be comprehensive, there is a requirement for a wide range of instrumentation and applications to be considered. In this dossier, the aim is to include as many aspects as possible that are relevant to modern approaches in lipid analysis. It is hoped that the articles will show how enormous advances have been made, and are continuing to be made, in this area. The range of techniques includes infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), ultraviolet (UV) spectroscopy and electron spin resonance (ESR) spectroscopy. IR spectroscopy can be subdivided further into mid‐ and near‐infrared and Raman spectroscopy, and the former may be coupled to gas chromatography (GC). NMR spectroscopy encompasses high resolution (further split into ¹ H, ¹³ C and ³¹ P) and time‐domain. MS can be subdivided according to the type of ionisation (e.g. electron impact, chemical ionisation, fast atom bombardment) or separation technique (e.g. GC, liquid chromatography) to which it is coupled, but is more conveniently considered according to the type of lipid (fatty acid, triacylglycerol, complex polar lipid) to be analysed. Analysis of stable isotopes in fatty acids involves a highly specialised application of MS. There is a host of applications ranging from the measurement of broad quality control parameters to highly specific determinations for research purposes, and includes both qualitative and quantitative information. Quality control applications include chemical parameters such as peroxide value by IR (as a possible replacement for more timeconsuming traditional methods) and physical parameters such as droplet size distribution by time‐domain NMR. Structural determinations of fatty acids and lipids by the various MS methods tend to be targeted towards specific research objectives.     

可逆/不可逆热致变色Schiff碱配合物的合成与性质

合成了双水杨醛缩对苯二胺（L₁）及其与锌（Ⅱ）的配合物（L₁Zn）和双水杨醛缩间苯二胺（L₂）及其与镍（Ⅱ）的配合物（L₂Ni）,利用核磁共振、红外光谱、紫外-可见光谱、荧光光谱和质谱对4种物质的结构和性质进行了表征。结果表明：两种Schiff碱化合物经二价金属离子配位后其荧光光谱均发生了蓝移现象;热激发实验发现L₁Zn具有可逆热致变色性质,而L₂Ni热致变色不可逆,表明它们是一类新型有机热致变色材料。     

Thermal degradation of flame‐retarded polyethylene/magnesium hydroxide/poly(ethylene‐co‐propylene) elastomer composites

Magnesium hydroxide‐based halogen‐free flame retarded linear low‐density polyethylene (LLDPE) composites containing poly(ethylene‐co‐propylene) (EP) elastomer were prepared by a melt process and subsequently vulcanized thermally. The thermal degradation of the composites was studied using thermogravimetric (TG) analysis and real‐time Fourier transform infrared (RT‐FTIR) spectroscopy. The combustion residues from the composites were characterized by Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS). The results from TG and RT‐FTIR tests show that the incorporation of a suitable amount of the elastomer into polyethylene/magnesium hydroxide composites after vulcanization increases the thermal stability. A graphite‐like char was found for the composites with EP elastomer, from Raman spectroscopy studies. XPS results indicate that there are several forms of carbon present in the combustion residues of the composites with EP elastomer, compared with only one form of carbon in the residues of the composites without the elastomer. Copyright © 2003 Society of Chemical Industry     

Electrodeposition of poly(indole-5-carboxylic acid) in boron trifluoride diethyl etherate containing additional diethyl ether

High quality poly(indole-5-carboxylic acid) (PICA) films were synthesized electrochemically by direct anodic oxidation of indole-5-carboxylic acid (ICA) in boron trifluoride diethyl etherate (BFEE) containing additional 80% diethyl ether (EE) (by volume). PICA films obtained from this medium showed good electrochemical behavior and good thermal stability with a conductivity of 10⁻² S cm⁻¹. The doping level of PICA increased during electrochemical growth processes. Dedoped PICA films were soluble in dimethyl sulfoxide (DMSO). The structure of the polymer were studied by UV-vis spectroscopy, FT-IR spectroscopy and ¹H NMR spectroscopy, which indicated that the polymerization occurred at C₍₂₎ and C₍₃₎ position. Fluorescent spectral studies indicated that PICA was a good blue-light emitter.