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Novel chemistry of Deep Eutectic Solvents (DES) is a matter of current interest as the unusual properties of these solvents make them a versatile medium for a variety of reactions. In particular, they provide media with a wide potential window and high ionic strength for the redox chemistry of metals. A wide range of type II DES (Metal halide (MX) + Hydrogen Bond Donor (HBD)) with AlCl3 (MX) have been synthesised, where hydrogen bond donors (HBD) included acetamide, methyl-, dimethyl-, trimehylacetamide, urea, di- and tetramethylurea. The ratio of AlCl3 - HBD was maintained at 1.5:1 throughout. Viscosity and conductivity of these novel DES, have been related to the melting point of HBD as well as to the availability of proton exchanging groups. Mechanisms of aluminium deposition/dissolution from room temperature chloroaluminate melts were studied in order to elucidate the effects of amines type on the properties of these novel electrolytes. Mass transport and speciation were investigated by means of Electrochemical Quartz Crystal Microbalance (in dispersive mode), UV-Vis and NMR. It was found that although the higher deposition rate was proportional to the higher conductivity of the respective DES, the rate of the stripping process was related to the type of HBD used. Creation of an aluminium based battery requires a balance between current efficiency and deposition rate and this can be achieved by a choice of suitable HBD. The influence of surface tension of DES on their electrochemical properties, and ultimately availability of proton exchanging groups to participate in liquid formation is currently under investigation. Figure 1

A non-aqueous zinc–polyaniline secondary battery was fabricated with polyaniline Emeraldine base as cathode and zinc metal as anode in an electrolyte consisting of 0.3 M zinc-bis(trifluoromethyl-sulfonyl)imide Zn(TFSI) 2 dissolved in propylene carbonate. We observed that the formation of the battery required a prerequisite condition to stabilize the interfaces in order to maintain a stable capacity. The battery suffered from Zn dissolution which induces a competition between concurrent Zn dissolution and plating when the battery is in charge mode, and thus inefficient cycles are obtained. The capacity and coulombic efficiency of the battery depends on the charge–discharge rates. We propose cycling protocols at different rates to determine the steady-state rates of competing reactions. When the cell is cycled at ≥1 C rate, the coulombic efficiency improves. The maximum capacity and energy densities of the battery are 148 mAhg −1 and 127 mWhg −1 , respectively for discharge at C/2. The battery was successively charged/discharged at constant current densities (1C rate), and high cycling stability was obtained for more than 1700 cycles at 99.8% efficiency. Zinc dissolution and self discharge of the battery were investigated after 24 h of standby. The investigation showed that the battery experiences a severe self-discharge of 48% per day.

Although mineral oils are commonly used as lubricants their emission particularly in marine environments can cause significant impact. In the current study the properties of water miscible deep eutectic solvents and ionic liquids are compared with a typical mineral base oil to ascertain their efficacy for potential marine lubricants. The environmental compatibility of some of the liquids, particularly choline chloride and glycerol, makes it an interesting potential base lubricant. Surprisingly some DESs showed very low corrosion rates with steel, nickel and aluminium even when the liquids contained water. This is a surprising result given that the chloride ion concentration is approximately 5 mol dm−3.

The electrodeposition of aluminium is demonstrated using a eutectic mixture of aluminium chloride and urea. The mixture is shown to be conducting through the formation of both cationic ([AlCl2·urean](+)) and anionic (AlCl4(-)) species and electrodeposition is achieved through the cationic species. The use of a biphasic system with the ionic liquid and a protective hydrocarbon layer allows metal deposition to be carried out in an environment with ambient moisture without the need for a glove box. A direct comparison is made between the AlCl3:urea and imidazolium chloride:AlCl3 systems and the differences in speciation and mass transport manifest themselves in different deposit morphologies. Brighteners which work in the chloroaluminate system such as toluene and LiCl are shown to be ineffective in the urea based system and the reasons for these differences are ascribed to the mechanism of the anodic reaction which is rate limiting.

Biscyclometallated iridium complexes [Ir(ppz)2(X^Y)][PF6] (X^Y = pyridine imine) have been synthesised. The pyridineimine ligands are prepared in situ during the complexation. The complexes show room temperature emission between 640 and 780 nm in CH2Cl2 solution. The emission is red shifted compared with the analogous bipyridine complex [Ir(ppz)2(bipy)][PF6]. DFT calculations have been used to shed light on the influence of the imine substituent on the electrochemical and photochemical properties. In particular, the calculations suggests that there is a significant change in geometry between the ground state and the first triplet excited state for arylimines but not for alkylimines, leading to much weaker emission for the arylimine complexes. The work demonstrates that pyridineimines can be used as a substitute for bipyridines in luminescent iridium complexes.

Electrochemical and transport properties were measured for hydrated chloride salts of copper and tin in ethaline, which is a 1:2 ratio of choline chloride and ethylene glycol. Density, viscosity and conductivity for ethaline melts with different salt concentrations have been measured for temperatures between 293 and 328 K. The change in formal potential with changing metal ion concentration has been determined to evaluate changing speciation in the ionic liquid. Cyclic voltammetry has been carried out to ascertain the reduction potential and diffusion coefficient of the reacting species. For pure ethaline the density was found to decrease by ,5% with increase in temperature. On the other hand, the viscosity was found to decrease and conductivity was found to increase by 65% over the same temperature range. The inclusion of metal salts in ethaline had negligible effect on these parameters. Potential measurements showed that copper was reduced through a two-step mechanism and Sn was reduced via a two electron transfer route. The diffusion coefficient values for Cu 2z and Sn 2z species were 1?22610 211 and 1?96610 211 m 2 s 21 respectively.

Mechanistic studies are reported for redox switching (doping/undoping) of Au-supported poly(3,4-ethylenedioxythiophene) (PEDOT) films exposed to LiClO 4 /CH 3 CN (a conventional electrolyte based on a molecular solvent) and to Ethaline and Propaline (two choline chloride-based deep eutectic solvent (DES) media). A combination of electrochemical, acoustic (quartz crystal microbalance, QCM) and optical (probe beam deflection, PBD) methods was used to monitor the exchange of mobile species between the film and the bathing electrolyte. Qualitatively, film responses to a potentiodynamic control function showed that the redox switching mechanisms are quite different in all three media. When exposed to acetonitrile, anion transfer is dominant, with some accompanying solvent transfer but negligible cation transfer; application of the convolution protocol allowed these transfers to be quantified. Analogous observations in the DES media could be interpreted qualitatively in terms of dominant cation transfer, but the convolution protocol could not be used to quantify the contributions of individual species; in these viscous media, this is a consequence of the long transit times from the film/solution interface to the optical detection zone. Chronoamperometric experiments, in which the measurement time was an order of magnitude (or more) longer permitted the diffusional processes driven by the polymer/DES interfacial population changes to reach the optical detection zone.

Electroplating is a key technology in many large-scale industrial applications such as corrosion-resistant and decorative coatings. Issues with current aqueous processes, such as toxicity of reagents and low current efficiencies, can often be overcome by using ionic liquids, and this approach has turned ionometallurgy into a fast-growing area of research. This review outlines the interactions in ionic liquids that are responsible for the advantageous properties of these solvents in electroplating. It summarizes recent research in which these properties have been analyzed or exploited and highlights fundamental issues in research and technology that need to be addressed.

It has previously been shown that eutectic mixtures of quaternary ammonium salts and hydrogen bond donors form liquids with properties similar to ionic liquids [1; 2]. These so-called deep eutectic solvents (DESs) have been shown to have physical properties which would make them useful as base lubricants. The base lubricant needs to show specific properties, including high viscosity index (VI), low friction coefficient (μ), low pour point and corrosivity. To determine the applicability of DESs as base lubricants, physical properties, corrosion and lubrication properties for four type III DESs have been studied and the results have been compared with mineral base oil. The data show that the lubrication properties of DESs are superior to mineral base oil for short distances. All DESs assessed here have higher VI (191, 147, 121 for Ethaline, Glyceline and Reline respectively compared with 100 for mineral base oil), lower pour points than mineral base oil and most of the liquids studied have shown very low co...

A new methodology is described for the removal of surface oxide scale from single crystal aerospace castings of nickel based superalloys using anodic electrolytic etching (electropolishing) with a novel choline chloride based ionic liquid, also known as deep eutectic solvent. This method enables the removal of scale from as cast components facilitating further critical quality checks and assessments, for example grain structure inspection, before the heat treatment. In addition, removal of scale prior to heat treatment also helps to mitigate other defect formation in single crystal castings such as surface incipient melting. Consequently, this methodology may offer significant potential process advantages over current manufacturing practice in that defective components can be identified earlier and, critically, before the expensive and time consuming heat treatment process. Here details are presented of some of the challenges, methodologies as well as characterisation of model test pieces and turb...

Redox-driven ion transfer processes accompanying p-doping and undoping were investigated for poly(3,4-ethylenedioxythiophene) (PEDOT) films. The PEDOT films were potentiostatically grown from acetonitrile solutions of monomer onto the Au electrodes of 10 MHz AT-cut quartz crystal resonators. The films were then sequentially exposed to 0.1 M LiClO4/CH3CN solution and to two deep eutectic solvent (DES) media, Ethaline 200 (choline chloride and ethylene glycol in 1:2 molar ratio) and Propaline 200 (choline chloride and propylene glycol in 1:2 molar ratio). In each case, the electron and ion transfer processes accompanying PEDOT redox switching were investigated using the EQCM. The maintenance of film electroneutrality was achieved in quite different ways in the three media. In contrast to anion transfer domination in 0.1 M LiClO4/CH3CN solution, cation transfer (in the opposite direction) was dominant in Ethaline 200. In Propaline 200, a two stage mixed mechanism was observed, with cation transfer domination in the early stages of p-doping (later stages of undoping) and anion transfer domination in the later stages of p-doping (earlier stages of undoping). The roles of thermodynamic and kinetic factors in these competitive situations were explored by observing the effect of experimental timescale (potential scan rate) in voltammetric experiments.

Surface scale occurs on the external surface of directionally solidified, single-crystal turbine components. It is one of the most important casting defects because it affects the grain orientation assessment and causes incipient surface melting during heat treatment. The formation of surface scale comprises a three-stage process: (1) formation of a 0.5- to 1.5-μm Al2O3 layer around the external surface of liquid metal as a result of the mold/metal reaction between the liquid and the mold prime coat; (2) separation of the solidified metal from the mold wall during cooling, where the Al2O3 layer is stripped away from the metal surface but remains adhered to the mold; and (3) subsequent oxidation of the “bare” metal to form an oxide scale at the surface. The scale comprises a mixture of oxides. It is found that TiO2, Cr2O3, and Al2O3 form on components cast using the 1st generation alloy, SRR99; however, in the case of castings using the 3rd-generation alloy, CMSX10N it is a predominately nickel-rich oxide (likely to be NiO). On the unscaled surface, the mold and metal are in intimate contact during casting, and subsequent cooling and the Al2O3 layer around the external surface prevents subsequent oxidation of the casting surface.

The electrodeposition of metals using ionic liquids has received considerable attention during the last ten years. Recent developments have taken these novel electrolytes from laboratory to commercial scale. One of the factors limiting the development into practical plating systems is the understanding of how brighteners function. In this study we describe the addition of three polar additives and their effect upon the nucleation mechanism of zinc and the resultant morphology. It is shown that the structure of the zinc deposits is controlled by double layer properties and it is proposed that the brightening effect of ethylene diamine and ammonia are caused by their ability to inhibit the adsorption of chloride at the electrode surface. The deposition of most metals using ionic liquids results in apparently amorphous deposits, which tend to be actually nano-crystalline. The additives used in this study produce macro-crystalline deposits, which resemble those obtained from aqueous solutions.

In this work the use of glycerol as a hydrogen bond donor in Deep Eutectic Solvents is studied. The physical properties of choline chloride mixtures with glycerol are quantified and it is shown that eutectic mixtures can circumvent some of the difficulties of using glycerol as a solvent viz. high viscosity and high melting point. The solvent properties are characterised using polarity parameters and the values are similar to other ionic liquids although it is shown that this procedure is a poor method of characterising Lewis basicity. The application of these liquids to the esterification of glycerol is used as a demonstration of the ability to tune a reaction with the quaternary ammonium halide acting as a quasi-protecting group. The liquids represent a sustainable way of preparing non-toxic, tuneable solvent systems.

(2010). Metal finishing with ionic liquids: scale-up and pilot plants from IONMET consortium. Transactions of the IMF: Vol. 88, No. 6, pp. 285-293.

PurposeThe purpose of this paper is to present the optimisation of protocols for the immersion coating of silver onto copper‐track printed circuit board (PCB) assemblies, using a novel class of ionic liquid and to show the implementation of the scale up process.Design/methodology/approachVarious conditions (temperatures and silver concentrations) are studied individually under laboratory conditions and then optimised for a pilot scale demonstrator line that is used to process British Standard test coupons.FindingsThe use of these novel liquids for the immersion coating of silver produces silver dip coatings that are bright and even and which give solderability that is as good as the commercial aqueous, nitric acid based, electroless process without any solder‐mask interface etching.Research limitations/implicationsThe combined technology has been optimised for an immersion silver coating line. Further development work should be undertaken to tailor the technology for gold immersion coating of PCB assemblies.Originality/valueThe paper details a process in which no solder‐mask interface etching is observed; that does not require the use of strong inorganic acids or expensive catalysts to sustain deposition and which does not appear to be light sensitive in contrast to other processes.

Vesicle fusion was used to deposit mixed dimyristoyl phosphatidylethanolamine–dimyristoyl phosphatidylserine (DMPE–DMPS) phospholipid bilayers on Au electrodes. Bilayer structure and composition, when exposed to aqueous NaF and subject to an applied electrochemical potential, were studied using electrochemical, spectroscopic and neutron reflectivity (NR) techniques. Interfacial capacitance data indicate the formation of compact films. Chronocolometric data show that surface charge is significantly altered by the presence of lipid in the potential range −0.75 < E/V (Ag|AgCl) < 0.35. NR measurements were made on lipid films in which the hydrocarbon tails were either fully hydrogenous (h-DMPE–h-DMPS) or perdeuterated (d-DMPE–d-DMPS), in each case serially exposed to D2O and H2O electrolytes and subject to different applied potentials. Guided by simulations of candidate interfacial structures, these yield the spatial distributions of lipid and solvent within the layers. Adjacent to the electrode, a compact inner leaflet is formed, with potential-dependent solvent volume fraction in the range 0.09 < ϕS < 0.19; there was no evidence of an intervening water layer. The outer leaflet contains rather more solvent, 0.52 < ϕS < 0.55. NR-derived film thickness and PM-IRRAS intensity data show that the lipid molecules are tilted from the surface normal by ca. 26°. Bilayer solvation and charge data show a strong correlation for the inner leaflet and very little for the outer leaflet.

The deposition of aluminium from a chloroaluminate based ionic liquid was studied to elucidate the effect of a diluent (toluene) and electrolyte (LiCl) on the deposit morphology. A wide variety of analytical techniques was applied to this system to determine the speciation and mechanism of material growth. These included: (27)Al NMR, FAB-MS, cyclic voltammetry, chronocoulometry, chronopotentiometry, scanning electron microscopy and atomic force microscopy. It was found that under-potential deposition (upd) causes a change in the way in which metal grows on the electrode surface. Metal grows in two regimes which are believed to be nano-material and bulk material. The addition of toluene causes a change in speciation and a decrease in upd which in turn changes the morphology of the deposit obtained and can lead to mirror finish aluminium. The addition of LiCl has the opposite effect encouraging upd and leading to larger crystallites and a dark grey deposit. It is also shown for the first time that under many conditions the rate of the anodic dissolution process is overall rate controlling and one effect of the addition of toluene is to increase the rate of anodic dissolution.

Crown ether functionalised conducting polymer films were used to complex barium ions from acetonitrile solution. It was found that fully-functionalised N-derivatized polypyrrole films do not possess adequate mechanical stability, but dilution with unfunctionalised bithiophene co-monomer leads to a series of copolymer films with excellent stability. Film reactivity, composition and structure were investigated using electrochemical, nanogravimetric, FTIR, XPS and neutron reflectivity techniques. The first three of these provided spatially integrated barium populations and neutron reflectivity provided spatially resolved compositional profiles. Measurements at various stages of film fabrication yielded spatial distributions of co-monomer, crown ether, solvent and barium (as perchlorate) components. Critically, the amount of free volume to accommodate crown motifs and barium within the film was limited by the film's internal microstructure and solvent content; the low solvent volume fraction creates a different local environment to solution.

Reported here are results of a systematic study into the electrolytic deposition of Zn metal from ionic liquids based on eutectic mixtures of choline chloride (ChCl) with either ethylene glycol (Eg) or urea. Cyclic voltammetry and gravimetric acoustic impedance spectroscopy (EQCM) techniques have been used to probe mass-transfer and charge-transfer mechanisms. The results show that nucleation in the urea based liquid is fast but bulk growth is slow, whereas nucleation in the glycol based liquid is slow but bulk growth is relatively fast. Critical surface coverage necessary for the transition from nucleation to bulk growth is similar for both liquids. Additionally, ex situ atomic force microscopy (AFM) has been used to probe the morphology of the metallic deposit at two different potentials during a linear sweep voltammogram.

Here we describe the electrolytic deposition of a range of metallic coatings, alloys and composites from room temperature ionic liquids that have low environmental impact/toxicity, are inexpensive and easy to handle. We show that some of these systems can be considered as "drop-in" replacement technologies for existing aqueous processes that currently utilize strong inorganic acids and highly toxic reagents.

Time-resolved specular neutron reflectivity measurements are presented and interpreted for electroactive polyvinylferrocene (PVF) films subject to potentiodynamic electrochemical control. New data acquisition methodology allows an effective measurement time scale on the order of seconds, which is an improvement over conventional methodology by 2 to 3 orders of magnitude. Reflectivity profiles were obtained for PVF films exposed to aqueous 0.1 M NaClO4 in which PVF films are thermodynamically permselective, with contrast variation via H2O and D2O. Irrespective of any model, the raw profiles show chemically reversible film "breathing" due to redox-driven solvent entry and exit during polymer oxidation and reduction, respectively. Modeling reveals three compositionally distinct regions within the polymer film: interfacial regions at the electrode and solution interfaces and a "bulk" interior. The new methodology, supported by simultaneous in situ visible transmission spectroscopy, reveals an unprecedented level of insight into the temporal and spatial mechanistic details of film solvation changes, including a two-stage (de)solvation mechanism for redox switching, differences in interior (in)homogeneity for reduced and oxidized films, and permselectivity failure under dynamic electrochemical conditions for the reduced (but not oxidized) state, in contrast to static conditions that allow permselectivity for both states.

The electrolytic deposition of nickel is demonstrated using a solution of the metal chloride salt separately in either a urea or ethylene glycol/choline chloride based ionic liquid. It is shown that the deposition kinetics and thermodynamics differ from the aqueous processes and these result in different deposit morphologies. It is also shown for the first time that bright metal coatings can be obtained from these liquid systems by adding various brightening agents and deposits can be put directly onto substrates such as aluminium without prior treatment. The general mechanism by which brighteners function in ionic liquids is also discussed.

Ionic liquids are molten salts that have low melting points. This review concentrates upon eutectic mixtures of quaternary ammonium salts and metal salts (usually halides). These so-called eutectic based ionic liquids can be used for the electrodeposition and dissolution of a wide range of metals and alloys. The review highlights the technological challenges involved in the application of ionic liquids to metal finishing.

This work demonstrates that a sustained galvanic coating of silver can be deposited onto copper substrates from a solution of Ag + ions in an ionic liquid (IL) based on a choline chloride (ChCl) eutectic. The sustained growth of the silver deposit was facilitated by the porous nature of the film and is proven using acoustic impedance spectroscopy on a quartz crystal microbalance (QCM). The silver and copper surfaces were characterised using atomic force microscopy (AFM) and scanning electron microscopy (SEM/EDX). In the commercial process of dip coating silver from ions in aqueous media, deposition does not continue once surface coverage has been achieved, without the use of catalysts. The process reported here using ionic liquids produces silver deposits of several microns by dip coating without the use of catalysts or strong inorganic acids.

Eutectic mixtures of zinc chloride and donor molecules such as urea and acetamide are described and it is proposed that these constitute a new class of ionic liquids. FAB-MS analysis shows that the liquids are made up of metal-containing anions and cations in which the donor is coordinated to the cation. Data on the viscosity, conductivity, density, phase behaviour and surface tension are presented and these are shown to be significantly different to other related ionic liquids that incorporate quaternary ammonium salts. The conductivity and viscosity are comparable with other ionic liquids and the data fit well to the Hole theory model recently proposed.

Here we describe the electrolytic deposition of Zn, Sn and Zn/Sn alloys from a solution of the metal chloride salts separately in urea and ethylene glycol/choline chloride based ionic liquids. We show that the deposition kinetics and thermodynamics differ from the aqueous processes and that qualitatively different phases, compositions and morphologies are obtained for the metal coatings in the different ionic liquid systems. We have quantified the electrochemical stripping responses using cyclic voltammetry together with compositional analysis using SEM/EDAX and X-ray diffraction. The differences in electrochemical responses are rationalised in terms of the speciation of both Zn and Sn chlorides in the ionic liquids that have been identified using FAB mass spectrometry. Also we demonstrate that composite metal coatings, e.g. containing Al2O3 particles, can be obtained from these liquid systems by virtue of the stable liquid suspensions. This novel feature of these liquids is a function of their relatively high viscosity.

This paper describes studies of a combined electrochemical/acoustic wave sensor for detection of metal ions in aqueous solutions. The sensor is based upon surface complexation of the metal ions at thiodisuccinic acid (TDS) functionalised self-assembled monolayer (SAM) modified electrodes on 10 MHz AT-cut quartz resonators, functioning as a quartz crystal microbalance (QCM). The SAM-modified electrodes were employed for the detection of Cd(II) ions in single and mixed metal ion solutions, with Pb(II) or Cu(II) as the interferants. Acoustic determination was based on the QCM frequency change associated with the binding to the surface-immobilised ligand of metal ions as a function of their concentration. Frequency response data were acquired under emersed and immersed conditions for ligand binding to the Au electrode and, subsequently, metal ion binding to the ligand. In the latter case, the data were interpreted according to a range of isotherms, of which the Temkin isotherm was found empirically best to describe the concentration dependence. The acoustic wave data yielded information on equilibrium binding stoichiometry and energetics. The extent of metal ion binding was also determined by coulometric assay (upon reduction to the zero-valent metal) after transfer to metal ion-free electrolyte solution. XPS studies of surface-bound metal-TDS ligand complexes confirmed the binding stoichiometry obtained from the electrochemical and acoustic wave responses, and provided information on the ligand–substrate binding and bound analyte oxidation state.

We demonstrate the first practical alternative to the use of phosphoric and sulphuric acid mixtures for the electropolishing of stainless steel. In this paper, efficient electropolishing of type 316 stainless steel is demonstrated in an ionic liquid composed of ethylene glycol (HOCH2CH2OH) and choline chloride (HOC2H4N(CH3)3+Cl−). Linear sweep voltammetry, chronoamperometry, scanning electron microscopy, atomic force microscopy and AC impedance methods were used to investigate the steel dissolution mechanism and the results are compared to polishing done in aqueous acidic solutions. It is shown that the quality of the polish is related to the breakdown of the oxide film and preliminary data suggest that the polishing process may be controlled by the diffusion of chloride ions. The dissolution is different from that found in aqueous acid solutions, and oxide breakdown is shown to be slower, which can lead to pitting at low current densities.

The viscoelastic properties of thin films of poly(3,4-ethylenedioxythiophene) (PEDOT) have been studied using the method of acoustic impedance. The films were deposited on the Au electrodes of 10 MHz AT-cut quartz thickness shear mode resonators and exposed to acetonitrile solutions of 0.1 M TEABF4 and LiClO4. For p-doped films, admittance spectra as a function of potential (E), temperature (T), and time scale (frequency, via harmonics, in the range 10-110 MHz) were acquired. Shear modulus components extracted from these responses surprisingly showed virtually no variation with E (and thus film solvation) or with T, but the variation with frequency was dramatic. This qualitative behavior and the numerical values of the shear moduli contrast strongly with recently reported data for the related poly(3-hexylthiophene) system, which shares the same conducting spine but differs substantially in the substitution pattern. Accordingly, the models and interpretation for PEDOT are quite different: film dynamics are determined by free-volume effects, and side-chain motion is not a significant factor. Qualitatively similar potential and time-scale effects were seen for n-doped PEDOT, but the scope of the measurements was limited by film stability.

On the basis of single crystal diffraction analyses it is shown that conversion of 13H-dibenzo(a,i)fluoren-13-one into its oxime causes distortion of the aromatic framework because of steric crowding. The oxime is, in consequence, chiral.Key words: oxime, crystal structure, chirality.

The crystal structure of trimethylammonio n-hexadecylsulfonamidate contains antiparallel monolayers stabilized by strong C−H···O bonds (C···O 3.22 A). There are also significant C−H···X (X = N, O) bonds linking adjacent layers. The structure suggests that nitrogen ylides have potential as amphoteric surfactants. The crystallography of paraffinic monolayers is discussed and the crystal structures of n-C16H33X compounds are shown to belong to three distinct types.

Several strategies are investigated for ‘activating’ polypyrrole electrodes for use in electrochemical supercapacitors. These include: the development of columnar morphologies by micellar deposition, self-doping by attachment of anions, and the use of aryl sulfonates to promote cross-linking and hydrophilicity. The key to improved performance, especially in this last example, is the apparent coupling of doping processes to structural relaxations that encourage solvent uptake by the polymer and ready access for dopant ions to all available sites. Thick (15–20 μm) films of polypyrrole activated in this way can be charged and discharged reversibly at scan rates up to 300 mV s −1 , indicating a possible use in high-power supercapacitors.

Polypyrrole (pPy) electrodes containing polysulfonated aromatic anions are investigated by cyclic voltammetry as electrodes for use in electrochemical supercapacitors. These ‘ladder-doped’ materials are deposited as thick films (ca. 10 μm) having open structures that permit the rapid insertion/ejection (up to 300 mV s −1 ) of cations and anions from aqueous solution, and give an effective or ‘geometric’ capacitance of up to 0.40 F cm −2 . The ‘dual mode’ doping behaviour seems essential for good capacitive response. These electrodes show a remarkable tendency to perform better at high cycling rates, an effect attributed to the way the structure ‘self-organises’ during the self-doping process. Good electrode response depends on protecting the open structure containing hydrophilic ion-conducting channels.

The diynol ester PhC(O)OCH2CC–CCCH2OH readily forms very long (4 cm) needle-shaped crystals. The crystal structure in the range 100–293 K contains strong O–H⋯O hydrogen bonds which link molecules related by the operation of a 21 screw axis into chains which are parallel to the long axis of the needle. Coefficients of linear expansion suggest that attractive intermolecular forces are strongest in the direction of the needle axis.

Crystals of 9-methylfluoren-9-ol, C(14)H(12)O, undergo a reversible phase transition at 176 (2) K. The structure of the high-temperature alpha form at 200 K is compared with that of the low-temperature beta form at 100 K. Both polymorphs crystallize in space group P1 with Z = 4 and contain discrete hydrogen-bonded R(4)(4)(8) ring tetramers arranged around crystallographic inversion centres. The most obvious changes observed on cooling the crystals to below 176 K are an abrupt increase of ca 0.5 A in the shortest lattice translation, and a thermal transition with deltaH = 1 kJ mol(-1).

Here we discuss the thermotropic and electrochemical properties and polymerisation of a series of N-substituted pyrrole monomers bearing mesogenic 4-substituted azobenzene attached as a pendant group via alkyl spacers. We discuss the effect upon these molecular properties of chain length and substitution of the azobenzene moiety with methoxy, cyano and nitro terminal groups. Additionally we present here the first crystal structure determination and analysis of two N-alkylpyrroles bearing mesogenic groups.

Electrodeposition is commonly used for the deposition of metallic and composite coatings. It is useful as it can coat complex 3D structures and can be used for the deposition of alloys. There are a few disadvantages; it is relatively slow to build up thick coatings and in some cases the current efficiency can be low. In this study a fundamentally different method for carrying out electrodeposition is demonstrated which can potentially be used for additive manufacturing. Here instead of dissolving metal from the anode and depositing it on the cathode a powder of the coating metal is put in contact with the cathode and pulse plating sequentially dissolves metal from the powder and then deposits it between the powder grains. By this method super-efficient deposition (efficiency >100%) can be achieved and thick layers can quickly be deposited. This can in principle be carried out in any media but in this study ionic liquids were used to increase the current efficiency of the process. The method is demonstrated using both zinc and copper. It is shown that using these media certain crystal planes can be promoted and ordered deposits are obtained. In addition the same technique was used to deposit composite materials by staring with a mixture of metal powder with ceramic powders, such as alumina, silicon carbide. The morphology of the surfaces was characterized using SEM, X-ray diffraction, and 3D optical microscopy techniques.

The electrodeposition of chromium is a technologically vital process, which is principally carried out using aqueous chromic acid. In the current study, it is shown that eutectic mixtures of urea and hydrated chromium(III) chloride provide a liquid which reduces the toxicological issues associated with the current aqueous Cr(VI) electroplating solution. Using EXAFS, mass spectrometry and UV-Vis spectroscopy, it is shown that chromium is present predominantly as a cationic species. Conductivities are higher than for most comparable ionic liquids. It is shown that the electrodeposition of chromium is electrochemically reversible, with a current efficiency much higher than in aqueous electrolytes. Surface tension and density measurements indicate that hole theory is a valid model to describe transport properties in these liquids. Bulk Cr deposits are not macrocrystalline but they are generally crack-free. The deposits have a hardness of 600 ± 10 Vickers and, as such, are comparable to deposits from aqueous systems.

In this paper we report one of the first examples of a soluble, fusible liquid crystalline polypyrrole. We describe the synthesis and characterisation of two pyrrole-based monomers substituted at the N-position with the mesogenic group 4-cyanobiphenyl. The mesogenic group is separated from the pyrrole moiety by an alkyl chain of either 3 or 11 methylene units length. We discuss the spectroscopic and thermotropic properties of these monomers and describe their oxidative polymerisation using electrochemical methods and separately using FeCl3 and I2 as chemical oxidants.

Here we describe the use of environmentally benign Deep Eutectic Solvents (DESs) to electropolish oxide casting scale from Ni based superalloy turbine blades. These new electrolytes are a viable alternative to hazardous and aggressive aqueous acids and etchants currently used to process these components. In addition we show that the DES electrolytes selectively expose the underlying surface structure of these superalloys. We demonstrate the ability of these electrolytes to preferentially etch either γ or γ′ phases depending on the choice of electrolyte formulation and the applied potential during the electrolytic etch on CMSX-4 ® and CMSX-10 ® alloys.

This study has shown for the first time that digital holographic microscopy (DHM) can be used as a new analytical tool in analysis of kinetic mechanism and growth during electrolytic deposition processes. Unlike many alternative established electrochemical microscopy methods such as probe microscopy, DHM is both the noninvasive and noncontact, the unique holographic imaging allows the observations and measurement to be made remotely. DHM also provides interferometric resolution (nanometer vertical scale) with a very short acquisition time. It is a surface metrology technique that enables the retrieval of information about a 3D structure from the phase contrast of a single hologram acquired using a conventional digital camera. Here DHM has been applied to investigate directly the electro-crystallization of a metal on a substrate in real time (in situ) from two deep eutectic solvent (DES) systems based on mixture of choline chloride and either urea or ethylene glycol. We show, using electrochemical DHM that the nucleation and growth of silver deposits in these systems are quite distinct and influenced strongly by the hydrogen bond donor of the DES.

A range of pyrrole monomers with carboxyl derivatives both at the N-, and β-ring positions were synthesized and, subsequently, were polymerized electrochemically at carbon, gold, and platinum electrodes. The resulting polymers, which were characterized with both electrochemical and spectroscopic methods, were then used to investigate the importance of polymer oxidation potential, polymer functionality, and backbone conductivity on the redox interaction with the small redox protein, cytochrome c. By choosing monomer substituents with varying side-chain length and steric bulk, it was possible to probe the nature of the protein−polymer interaction and to show how the heterogeneous rate constants, ks, as an estimate for electron exchange between the electrode functionalized poly(pyrroles) and the protein, varied as a consequence of the structure of the matrix. The method provides a novel route for the modification of a wide range of conducting surfaces for the study of biological interfacial reactions, partic...

Silver is an important metal for electronic connectors, however, it is extremely soft and wear can be a significant issue. This paper describes how improved wear resistant silver coatings can be obtained from the electrolytic deposition of silver from a solution of AgCl in an ethylene glycol/choline chloride based Deep Eutectic Solvent. An up to 10-fold decrease in the wear volume is observed by the incorporation of SiC or Al(2)O(3) particles. The work also addresses the fundamental aspect of speciation of silver chloride in solution using EXAFS to probe solution structure. The size but not the nature of the composite particles is seen to change the morphology and grain size of the silver deposit. Grain sizes are shown to be consistent with previous nucleation studies. The addition of LiF is found to significantly affect the deposit morphology and improve wear resistance.

PurposeThe purpose of this paper is to detail progress on the European Commission supported FP7 ASPIS project that is undertaking a multi‐faceted approach to develop novel and improved nickel‐gold (ENIG) solderable finish chemistries and processes in order to overcome issues such as “black pad” that are known to cause reliability issues.Design/methodology/approachThe ASPIS project has four key and discrete approaches; research into “black pad” formation mechanisms, development of new aqueous chemical deposition methods, formulation of new processes based on ionic liquids and the development of prognostic screening tools to enable early prediction of reliability issues.FindingsKey factors influencing “black pad” formation include immersion gold bath pH value, concentration of citrate and thickness of the immersion gold layer. In addition, copper substrate preparation is also important. Work to develop new metal deposition processes using ionic liquids has also been demonstrated and may provide a viable alternative to more conventional aqueous based chemistries, thereby enabling some of the conditions that lead to “black pad” to be avoided.Research limitations/implicationsThis paper summarises the work carried out in the first year of a three‐year project and so the outputs to date are relatively limited. The project is continuing for another two years, when further progress will be made. It is hoped to report this progress in a future update paper.Originality/valueThe ASPIS project has undertaken multiple approaches to the development of new high reliability nickel gold finishes and this combination of approaches should offer synergies over more discrete traditional methodologies. As well as undertaking a detailed analysis of the mechanisms causing reliability problems, radical new formulation and prognostic approaches are also being developed.