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We report the synthesis of a new conjugated polymer bearing crown ether moieties, poly[(

[Hypothesis]: The milder interaction with biosystems makes the zwitterionic surfactants an important class of surfactants, and they are widely used in biological applications and in personal care formulations. An important aspect of those applications is their strong synergistic interaction with anionic surfactants. It is anticipated that the strong interaction will significantly affect the adsorption and self-assembly properties., [Experiments]: Surface tension, ST, neutron reflectivity, NR, and small angle neutron scattering, SANS, have been used here to explore the synergistic mixing in micelles and at the air–water interface for the zwitterionic surfactant, dodecyldimethylammonium propanesulfonate, C12SB, and the anionic surfactants, alkyl ester sulfonate, AES, in the absence and presence of electrolyte, 0.1 M NaCl., [Findings]: At the air–water interface the asymmetry of composition in the strong synergistic interaction and the changes with added electrolyte and anionic surfactant structure reflect the relative contributions of the electrostatic and steric interactions to the excess free energy of mixing. In the mixed micelles the synergy is less pronounced and indicates less severe packing constraints. The micelle structure is predominantly globular to elongated, and shows a pronounced micellar growth with composition which depends strongly upon the nature of the anionic surfactant and the addition of electrolyte.

By combining oppositely charged polydiallyldimethylammonium chloride (PDADMAC) and sodium polyacrylate (NaPA), interpolyelectrolyte complexes (IPECs) can be formed in aqueous solution. Such IPECs are studied for rather short NaPA and under variation of the Mw of PDADMAC. The focus is on elucidating the effect of having a hydrophobic modification of the NaPA, which is introduced by having 10 mol% of the monomeric units substituted by ones carrying a dodecyl alkyl chain. This modification renders the complexes more hydrophobic, which is seen in the fact that precipitation of the complexes occurs at a lower mixing ratio and the biphasic region is also wider. The structures of the soluble IPECs are studied by a combination of light and neutron scattering (SANS). It is observed that the complexes formed possess typical radii of gyration of ≈30–40 nm, which become somewhat smaller with increasing length of the PDADMAC chain. The SANS data can be described well with the Beaucage model for complexes, where locally small hydrophobic domains of cylindrical shape are formed, whose persistence length decreases with increasing content of NaPA in the complexes. In contrast no such structures are seen for NaPA without the hydrophobic modification. The cylindrical domains are then arranged within larger-sized clusters of 30–40 nm, which become more compact with reduced length of the PDAMAC chains. The structure of the IPECs is largely determined by the presence of the hydrophobic modification of the NaPA and is further controlled by the length of the hydrophobic modification. Such IPECs of controlled structure, relatively small size, and containing hydrophobic domains are potentially interesting as delivery systems due to having domains of variable polarity.

Mechanical interlocking of molecules (catenation) is a nontrivial challenge in modern synthetic chemistry and materials science

Measurements have been performed on thermally equilibrated conjugated-polymer/insulating-polymer bilayers, using specular and off-specular neutron reflectivity. While specular reflectivity is only sensitive to the structure normal to the sample, off-specular measurements can probe the structure of the buried polymer/polymer interface in the plane of the sample. Systematic analysis of the scattering from a set of samples with varying insulating-polymer-thickness, using the distorted-wave Born approximation (DWBA), has allowed a robust determination of the intrinsic width at the buried polymer/polymer interface. The quantification of this width (12 Å ± 4 Å) allows us to examine aspects of the conjugated polymer conformation at the interface, by appealing to self-consistent field theory (SCFT) predictions for equilibrium polymer/polymer interfaces in the cases of flexible and semi-flexible chains. This analysis enables us to infer that mixing at this particular interface cannot be described in terms of polymer chain segments that adopt conformations similar to a random walk. Instead, a more plausible explanation is that the conjugated polymer chain segments become significantly oriented in the plane of the interface. It is important to point out that we are only able to reach this conclusion following the extensive analysis of reflectivity data, followed by comparison with SCFT predictions. It is not simply the case that conjugated polymers would be expected to adopt this kind of oriented conformation at the interface, because of their relatively high chain stiffness. It is the combination of a high stiffness and a relatively narrow intrinsic interfacial width that results in a deviation from flexible chain behaviour.

The fabrication and assembly of printed circuit boards (PCBs) involves the layering of metals onto an insulating substrate prior to the addition of electronic components. The interfaces between these metal layers are often subject to metal-metal interdiffusion, formation of brittle intermetallics and corrosion, compromising the integrity of the PCB-component solder joints. We have recently developed environmentally sustainable, non-toxic methodologies for application of metal PCB finishes using Deep Eutectic Solvents (DESs) as a novel solvent medium.1-3 Here we focus on the characterisation of metal-metal interfaces in DES media quantifying interfacial structure, layer thickness and morphology using a range of electrochemical and microscopy techniques, including chronoamperometry, cyclic voltammetry (CV) and novel simultaneous thickness electrochemical potential (STEP) measurements coupled with neutron reflectivity (NR.) We have developed the STEP methodology to ascertain some, if not all, of the same information that NR provides. Deposition of Ag and Cu layers has been carried out in different configurations onto Au substrates and characteristic STEP traces are presented for each upon galvanostatic stripping. The STEP methodology facilitates the identification and quantification of each metal layer by galvanostatic dissolution, which is comparable with time resolved NR measurements. The characteristic features of the STEP measurements are discussed including the shape and potential of the dissolution trace. The degree of mixing between the layers is qualitatively determined from E vs. t traces, along with the layer composition and thickness for systems in which layers remain discrete. In summary, we present a new, accessible and inexpensive technique, which probes the thickness, composition and interfacial mixing between layers in PCB metal systems using DES electrolytes and galvanostatic stripping methodologies. [1] A. D. Ballantyne, G. Forrest, M. Goosey, A. Griguceviciene, J. Juodkazyte, R. Kellner, A. Kosenko, R. Ramanauskas, K. S. Ryder, A. Selskis, R. Tarozaite and E. Veninga, Circuit World, 2012, 38(1), 21-29. [2] K. S. Ryder, A. D. Ballantyne, D. Price and T. Perrett, The PCB Magazine, February 2012, 22-30. [3] A. P. Abbott, S. Nandhra, S. Postlethwaite, E. L. Smith, and K. S. Ryder, Phys. Chem. Chem. Phys., 2007, 9, 3735–3743. Figure 1

Electrolytic coatings of metals such as nickel, chromium, zinc, silver and gold are commonly applied as decorative and/or functional coatings. Some of the functional benefits which metal coatings provide are corrosion resistance, wear resistance, electrocatalysis and use in magnetic applications. A range of strategic manufacturing industries are dependent on such electrolytic coatings including electronics, aerospace, automotive and energy. The vast majority of electrolytic coatings are plated from aqueous solutions but stringent health and safety legislation governing transport, use and disposal of feedstock chemicals has driven the challenge for innovation in electrolyte technology that facilitates coatings from less toxic materials and in a manner that is more efficient and more consistent with environmental and process sustainability. We have been motivated by this challenge and have developed a range of novel solvent systems for deposition of metal coatings as alternatives to existing process (e.g. Ni, Zn, Cu, Ag, Ag) as well as novel electrolytes for deposition of reactive metals such as Al. These electrolytes have become known as Deep Eutectic Solvents and have shown utility and promise in a range of metal finishing processes. [1] Whilst the thermodynamics, kinetics, metal ion speciation and growth processes of electrolytic coatings from aqueous solutions have been studied for more than one hundred years, little is currently known about these fundamental aspects of electrochemical deposition from DES media. [2] Here we describe our studies into the electrochemical characterisation of a range of metals in DES electrolytes. In particular, we will focus on aspects of growth and dissolution processes and how these effect the morphology and composition of metal films. We will describe the characterisation of thin metal films in DES media using a range of time resolved techniques including cyclic voltammetry, chronopotentiometry, chronoampertometry, gravimetry (QCM), neutron reflectometry (NR) and surface metrology. The use of in-situ electrochemical NR methods is novel and we will present new data on the growth and dissolution of single metal and bi-layer metals films. The Figure shows time resolved NR data for the electrochemical dissolution of a Cu/Ag bi-layer on a Au substrate. We will also present complimentary data on the characterisation of the same systems using so-called Simultaneous Thickness Electrochemical Potential (STEP) chronopotentiometric methods. We will consider the effect of small-molecule additives on surface morphology and finish (roughness) of electrolytic coatings. [3] Organic and inorganic additives are often added to electroplating solutions to improve surface finish, reduce roughness and promote uniform surface morphology of the coatings. Such additives are usually small molecules and often referred to as brighteners or levellers. However, there have been limited investigations into the effect of such additives on electrodeposition from ionic liquids (ILs) and deep eutectic solvents (DESs). Here we will describe the effect of four additives on electrolytic plating of exemplar metals, nickel and zinc, from an ethyleneglycol based DES; these are nicotinic acid (NA), methylnicotinate (MN), 5,5-dimethyl- hydantoin (DMH) and boric acid (BA). The additives show limited influence on the bulk speciation but have significant influence on the electrochemical behaviour of metal deposition. Small concentrations (ca. 15 mM) of NA and MN show inhibition of metal ion reduction whereas high concentrations of DMH and BA are required for a modest difference in behaviour from the additive free system. NA and MN also show that they significantly alter the nucleation and growth mechanism when compared to the additive free system and those with DMH and BA. Each of the additive systems had the effect of producing brighter and flatter bulk electrodeposits and with increased coating hardness. “Deep Eutectic Solvents (DESs) and their Applications”, Emma L. Smith, Karl S. Ryder and Andrew P. Abbott, Chem. Rev., 2014, 114, 11060. “EXAFS Study into the Speciation of Metal Salts Dissolved in Ionic Liquids and Deep Eutectic Solvents”, Jennifer M. Hartley, Chung-Man Ip, Gregory C.H. Forrest, Kuldip Singh, Stephen J. Gurman, Karl S. Ryder, Andrew P. Abbott and Gero Frisch, Inorg. Chem., 2014, 53(12), 6280. “Bright Metal Coatings from Sustainable Electrolytes: The Effect of Molecular Additives on Electrodeposition of Nickel from a Deep Eutectic Solvent”, Andrew P. Abbott, Andrew Ballantyne, Robert C. Harris, Jamil A. Juma and Karl S. Ryder, Phys. Chem. Chem. Phys., 2017, 19. 3219. Figure 1

Characterization of electroactive polymer films and their application in practical devices (electronic, chemical, sensing, energy storage, optical, actuator) tends to focus on the transfer of charged species (electrons and counter ions), since these are the entities most directly associated with the response to the electrochemical control function. However, transport rates of ions (“dopant”, in the context of conducting polymer systems) are dictated by solvent content of the film, which governs the local viscosity of the medium through which mobile species move. Further, the presence of solvent (and other small molecules) creates free volume that facilitates the dynamics of polymer motion, macroscopically seen as a plasticising effect on film viscoelasticity. In the light of the above, it is of value to determine the solvent content of electroactive polymer films; this is the focus of the present work. Experimentally, the challenge is that the solvent is (by choice) electrochemically “silent” and optically transparent, and its selective observation within a film exposed to a vast reservoir of bulk solution is not trivial. Nanogravimetric measurements made using the EQCM have provided innumerable insights into changes in film solvent population, e.g. in response to redox state changes, but the technique cannot provide absolute solvent population in the film. Spectroscopic techniques generally have difficulty in distinguishing solvent in a film from that in bulk solution, but reflectivity techniques do possess surface selectivity. Of these, ellipsometry has the advantage of rapid data acquisition, i.e. good time resolution, but modelling the data can present ambiguities. Here we use neutron reflectivity (NR) which, through the penetrating nature of neutrons, allows access to "buried" interfaces. Traditionally, the negative consequence of this weak interaction with matter is long data acquisition times; addressing this is the central feature of this presentation. Since neutrons interact with the nuclei in the system (cf. photons interacting with the electrons in ellipsometry), NR has the huge advantage of isotopic selectivity. This is commonly referred to as “contrast variation” and has the critical characteristic of allowing one to vary the visibility of a selected chemical component without (to a first approximation) altering the (electro)chemistry of the system. Most frequently, this is exploited by deuteration, since the neutron scattering lengths of H and D are very different. Correlation of the h- and d-system NR data sets removes ambiguities in modelling the data. We have previously used NR with solvent contrast variation to determine solvent volume fraction depth profiles, ΦS(z), in redox polymer films at equilibrium (fixed potential) and on long timescales during slow cycling. We now present data under dynamic conditions more relevant to fabrication or operation of a working device. This necessitates an order of magnitude improvement in time resolution. Instrumentally, the challenge can be met using more sophisticated detection systems, including event mode data capture, in which every incident/reflected neutron is detected individually. The dramatic increase in the size of data sets presents challenges in modelling the data, but the facility to (re-)select signal averaging time post experiment permits optimisation of competing aspirations of time resolution and signal-to-noise. This is key for single shot experiments, such as film deposition or evolution of film behaviour. Here we present neutron reflectivity data for aniline-, pyrrole- and thiophene-based polymer films. For these systems, we have the opportunity to exploit h- and d- variants of both solvent and monomer. Four significant insights are revealed. First, the data reveal that film deposition protocol (i.e. potentiostatic, potentiodynamic or galvanostatic control function) influences film solvation state and spatial distribution; while anecdotally suspected, this provides unambiguous quantitative evidence. Second, there are substantial spatial variations in film solvent content; this is a feature commonly not accommodated in models of modified electrodes. Third, for some systems, film solvent population and spatial disribution are "frozen" into the system during fabrication, so deposition protocol determines film characteristics in the longer term. Fourth, in selected cases the structure evolves with electrochemical manipulation, such that differently prepared films subsequently exposed to the same environment and history evolve to a common solvation profile. The implications of these phenomena for film design and handling are discussed for particular types of application.