There has been much interest in the construction of soft nanomaterials in solution due to a desire to emulate the exquisite structure and function of Nature's equivalents (e.g. enzymes, viruses, ...proteins and DNA). Nature's soft nanomaterials are capable of selectivity, precision and efficiency in areas such as information storage and replication, transportation and delivery, and synthesis and catalysis. To this end, the use of small molecules, amphiphiles, colloids, and polymers have been investigated for the development of advanced materials in myriad fields of biomedicine and synthetic chemistry. Two major challenges are faced in this area of research: the reproducible, scalable and precise synthesis of such constructs and the reliable, accurate and in-depth analysis of these materials. This tutorial review will focus on this second aspect and provide a guide for the characterisation and analysis of soft nanomaterials in solution using scattering and microscopic techniques.
Copper (Cu) corrosion is a compelling problem in the automotive sector and in oil refinery and transport, where it is mainly caused by the action of acidic aqueous droplets dispersed in an oil phase. ...Corrosion inhibitors, such as benzotriazole (BTAH) and its derivatives, are widely used to limit such corrosion processes. The efficacy of corrosion inhibitors is expected to be dependent on the surface crystallography of metals exposed to the corrosion environment. Yet, studies of the effect of additives at the local level of the surface crystallographic structure of polycrystalline metals are challenging, particularly lacking for the triple-phase corrosion problem (metal/aqueous/oil). To address this issue, scanning electrochemical cell microscopy (SECCM), is used in an acidic nanodroplet meniscus|oil layer|polycrystalline Cu configuration to explore the grain-dependent influence of an oil soluble BTAH derivative (BTA-R) on Cu electrochemistry within the confines of a local aqueous nanoprobe. Electrochemical maps, collected in the voltammetric mode at an array of >1000 points across the Cu surface, reveal both cathodic (mainly the oxygen reduction reaction) and anodic (Cu electrooxidation) processes, of relevance to corrosion, as a function of the local crystallographic structure, deduced with co-located electron backscatter diffraction (EBSD). BTA-R is active on the whole spectrum of crystallographic orientations analyzed, but there is a complex grain-dependent action, distinct for oxygen reduction and Cu oxidation. The methodology pinpoints the surface structural motifs that facilitate corrosion-related processes and where BTA-R works most efficiently. Combined SECCM–EBSD provides a detailed screen of a spectrum of surface sites, and the results should inform future modeling studies, ultimately contributing to a better inhibitor design.
Practically important metal electrodes are usually polycrystalline, comprising surface grains of many different crystallographic orientations, as well as grain boundaries. In this study, scanning ...electrochemical cell microscopy (SECCM) is applied in tandem with co-located electron backscattered diffraction (EBSD) to give a holistic view of the relationship between the surface structure and the electrochemical activity and corrosion susceptibility of polycrystalline Cu. An unusual aqueous nanodroplet/oil (dodecane)/metal three-phase configuration is employed, which opens up new prospects for fundamental studies of multiphase electrochemical systems, and mimics the environment of corrosion in certain industrial and automotive applications. In this configuration, the nanodroplet formed at the end of the SECCM probe (nanopipette) is surrounded by dodecane, which acts as a reservoir for oil-soluble species (
e.g.
, O
2
) and can give rise to enhanced flux(es) across the immiscible liquid-liquid interface, as shown by finite element method (FEM) simulations. This unique three-phase configuration is used to fingerprint nanoscale corrosion in a nanodroplet cell, and to analyse the interrelationship between the Cu oxidation, Cu
2+
deposition and oxygen reduction reaction (ORR) processes, together with nanoscale open circuit (corrosion) potential, in a grain-by-grain manner. Complex patterns of surface reactivity highlight the important role of grains of high-index orientation and microscopic surface defects (
e.g.
, microscratches) in modulating the corrosion-properties of polycrystalline Cu. This work provides a roadmap for in-depth surface structure-function studies in (electro)materials science and highlights how small variations in surface structure (
e.g.
, crystallographic orientation) can give rise to large differences in nanoscale reactivity.
Probing Cu corrosion in an aqueous nanodroplet/oil/metal three-phase environment revealed unique patterns of surface reactivity. The electrochemistry of high-index facets cannot be predicted simply from the low-index {001}, {011} and {111} responses.
Dithiomaleimides (DTMs) with alkyl substituents are shown to be a novel class of highly emissive fluorophores. Variable solubility and further functionalization can easily be tailored through the ...choice of N and S substituents. Inclusion of a DTM unit into a ROP/RAFT initiator or insertion into the disulfide bond of salmon calcitonin (sCT) demonstrates the utility for fluorescent labeling of polymers and proteins. Simultaneous PEGylation and fluorescent labeling of sCT is also demonstrated, using the DTM unit as both a linker and a fluorophore. It is anticipated that DTMs will offer an attractive alternative to commonly used bulky, planar fluorophores.
Microplastics are receiving growing attention in the public debate, while the scientific assessment of risks of microplastics to ecological and human health is still ongoing. Previous studies suggest ...concerns among the general public with country‐specific differences. However, little is known about the reasoning underlying these concerns. By conducting qualitative interviews with German (n = 15) and Italian citizens (n = 15), this study adopted a cross‐national perspective to investigate which concepts shape citizens’ perceptions of microplastics. A qualitative content analysis was used, with coding categories and subcategories developed inductively. Results showed that interviewees formed assumptions around microplastics despite own uncertainties, transferred knowledge from macro‐ to microplastics, and used the concepts of accumulation and dose–response relationship to make sense of the topic. Moreover, they saw the domains of human health and the environment as intertwined and expressed helplessness when discussing solutions to the microplastics issue. Many themes on the topic were similar in both samples, but there were also some differences. For instance, whereas Italian participants talked about marine‐related microplastics, German participants talked about airborne sources; also, German participants tended to recognize more strongly the actions their country was putting in place to address the problem. These findings underscore the need for proactive risk communication despite remaining gaps in scientific risk assessment. Beyond providing technical information, communicators should consider the reasoning behind risk perception on microplastics and address scientific uncertainty as well as the interconnectedness between the domains of human health and the environment.
A new class of brightly fluorescent and profluorescent methacrylate and acrylate monomers is reported. The fluorescent monomers contain the dithiomaleimide (DTM) fluorophore, which imparts a large ...Stokes shift (up to 250 nm) and bright emission. Furthermore, the simple and efficient chemistry of the DTM group, as well as its excellent processability (highly soluble, neutral functional group) makes monomer preparation straightforward. Copolymerisation at 10 mol% loading with a range of hydrophobic and hydrophilic monomers is demonstrated by RAFT polymerisation. Reactions proceed to high monomer conversion with excellent control over molecular weight (D sub(M) < 1.3) under standard polymerisation conditions. Incorporation of these fluorescent DTM-functional monomers has little effect on polymer properties, with PEG (meth)acrylate copolymers retaining their water solubility and thermoresponsive behaviour. A thiol-exchange reaction is also possible, whereby the thiol ligands of the pendent DTM groups can be exchanged by conjugate addition-elimination with an alternative thiol. Monomers containing the dibromomaleimide (DBM) group gave profluorescent copolymers. Reaction of the DBM group with thiols (to form the DTM group) corresponds to a chemico-fluorescent response, leading to an OFF-to-ON switching of fluorescence. This post-polymerisation functionalisation is shown to be fast and highly efficient (>95% conversion in 3 h), and by using thiols of different polarities can be used to progressively tune the LCST cloud point of a thermoresponsive polymer over a range of 11 degree C. Therefore, both DTM and DBM functional monomers provide a simple and effective tool for fluorescent labelling of (meth)acrylate polymers.
Amino-substituted maleimides form a new class of highly emissive compounds, with large Stokes shifts (>100 nm) and high quantum yields (up to ∼60%). Emission is responsive to the maleimide's ...environment with both a red-shift, and quenching, observed in protic polar solvents. Aminomaleimides are easily functionalised, providing a versatile fluorescent probe.
Enzymatic biofuel cells offer the exciting prospect of clean energy production for implantable devices, but such devices are still exotic and require improvements in electrode design and performance. ...Here a global strategy to prepare robust and versatile buckypaper bioelectrodes for advancing biofuel cell applications is presented. The fabrication method is based on a combination of original bifunctional polynorbornene copolymers with carbon nanotubes. Use of copolymers containing both pyrene and activated ester groups for cross-linking and tethering, respectively, increases the mechanical and electrochemical performance compared to buckypaper prepared without polymer or with the pyrene homopolymer. The amount of polymer used is an important parameter and was optimized to improve mechanical performance. High surface concentrations of reactive ester functionalities were obtained using long-chain polymers and exhibited high selectivity for attachment of aminoanthraquinone and the enzyme laccase. High performance biocathodes for direct oxygen reduction were constructed by immobilization of laccase on unmodified and anthraquinone-modified buckypapers. Anthraquinone-modified electrodes gave increased current densities due to improved electrical wiring of laccase via the hydrophobic pocket near the laccase T1 site. Biocathode stability over one month was excellent (53% current density after 24 days) and thus a new class of practical carbon-based enzymatic biofuels is envisioned.
Internal combustion engine lubricants are subject to thermo-oxidative degradation during use and must be designed to withstand oxidation in order to extend their useful life. Understanding the ...complex chemical process of thermo-oxidative degradation is essential to designing higher performing engine lubricants. In this study base oil samples composed of a Group II base oil, doped with three different levels of biodiesel (B0, B15, and B100), were subjected to benchtop oxidation testing of up to 168 h, which mimics the conditions experienced in an internal combustion engine. The resulting samples were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for ultrahigh-resolution characterization to monitor oxidation as a function of time and biofuel content. Both negative-ion nanoelectrospray ionization and positive-ion atmospheric pressure photoionization were utilized. Most of the oxidation products were found to be polyoxygenated species containing 1–8 oxygen atoms, with the number of detected species increasing with oxidation time. Assessment of the maximum carbon number of protonated classes indicated the involvement of oligomerization reactions; additionally, modeling of mean double bond equivalents (DBE) for each protonated class suggests increasing carbonyl content for each particular class with increasing oxidation time. The oxidations of B15 and B100 doped samples were compared to that of B0. B15 samples were found to correspond closely to B0 samples, with a similar number of species detected. B100 samples showed a significant increase in number of species generated at 24–72 h relative to B0 and B15; however, a similar number of species were observed at 168 h for all samples, indicating a similar level of base oil oxidation at the final oxidation point. FTICR MS is shown to afford new insights into base oil oxidation as a function of time and biofuel content.
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