INSTRUMENTATION
Richard A Campbell explains the impact of neutrons on optimising the engineering of formulations in the chemical industry.
Richard A Campbell erklärt die Auswirkung von Neutronen auf die Optimierung der Technik von Rezepturen in der chemischen Industrie.
Richard A Campbell explique l’impact des neutrons sur l’optimisation de l’ingénierie de formulation dans l’industrie chimique.
The neutron effect N
eutrons are ideal probes to characterise soft matter formulations. They have a
wavelength on the order molecular dimensions at about a thousand times shorter than visible light. An interference pattern is produced that can be used to resolve molecular structure when neutrons interact with nanostructures in solution or at interfaces. Furthermore, neutrons interact differently with different isotopes of the same sample, which means that isotopic substitution can be employed to deduce the bulk or surface composition of a mixture. As a result of neutrons being selective
to different species in the same mixture, they can be exploited to determine the activity of a particular component in a mixture. For example, if a new ingredient improves the performance of a given formulation, neutrons can be used to determine just how much of it is present in a bulk particle or at an interface. The Institut Laue-
Langevin (ILL) in Grenoble, France, is a research facility funded publically by several different countries and provides a resource for scientists who publish freely their results. Two techniques
Fig. 1. The nuclear reactor that sits at the heart of ILL and deliver neutrons to its suite of world class instruments including Figaro where they are used to probe the nature of matter at atomic scales.
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we routinely use to characterise liquid samples are neutron reflectometry (NR) for the properties and behaviour of surfaces and small- angle neutron scattering (SANS) for corresponding information in bulk solutions. In NR a
collimated beam of neutrons is reflected off samples at a grazing angle of only a degree or so, and free air/liquid interfaces as well as buried solid/liquid interfaces can be probed. Applications are quite diverse,
from protein/nanoparticle interactions concerning nanotoxicity to solvent-drying in paints to rheometry of polymer blends. In SANS a ray of neutrons transmits directly through the bulk sample and is slightly deflected. Areas of interest include the interactions of macromolecules with lipid vesicles, the organisation of proteins on nanoparticles and the self-assembly of surfactants in emulsion droplets. Many of the scientific domains studied
with neutrons are of fundamental interest to scientific researchers. However, ILL is developing equipment to study materials under industrially relevant conditions. Concerning NR, we have recently
supported a PhD project to develop an overflowing cylinder on the beamline where the surface is continually perturbed and samples are under steady state flow to recreate more realistic non-equilibrium conditions relevant to the processing and applications of commercial products. For SANS, we have developed a suite of devices for the study of complex fluids under shear flow in order to correlate the macroscopic rheological response of a material with its internal structure. With these resources we aim to bridge the gap between the fundamental understanding required by academic scientists and financial benefits to the chemical industry of optimising formulations under practically relevant conditions. The industrial significance of some very recent studies, two at surfaces characterised by NR and two in the bulk solution characterised by SANS. The first NR study concerns the
mechanism of formation of interfacial multilayers in strongly interacting polymer/surfactant mixtures. We invented a set of solid/liquid/solid interface cells to decouple of effects of surface self-assembly from the transport to interfaces under gravity of nanostructured
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