INSTRUMENTATION


particles1


. One single crystal sits above


and another sits below a liquid reservoir. The comparison of results at different interfaces of the same sample revealed that the surface properties were being influenced by the position of the interface, ie, gravity determined the surface properties due to phase separation. Such measurements at a single interface would have missed this point. We showed that the distinction of different interfacial mechanisms in a range of mixtures can lead to a better understanding of how formulations can be used to achieve optimum surface properties. Another recent NR study exploited


an overflowing cylinder which recreates practical conditions relevant to the processing and applications of formulations2


convection/spreading mechanism. This behaviour was almost exactly the opposite with what had been determined previously at static surfaces. It seems our ability to predict surface properties of formulations under dynamic conditions is missing. Recently, small-angle neutron


scattering experiments were used to study a new class of surfactants with magnetically-active sections containing iron3


pharmaceutical compounds to other areas of the body. Lastly, another industrially-relevant


area starting to be addressed by SANS is the application of soft materials in industry involving unusual complex flow behaviour4


. A range of rheology and flow . It was demonstrated that surfactant


micelles interact cooperatively in a magnetic field allowing the solutions to be manipulated with even with small magnet. The possibility to remove a soap after it has been added to a system widens potential large scale applications to areas such as oil spill clean-ups. The reason for the magnetic properties


. Here neutrons are skimmed


off the flowing liquid surface to reveal the composition of surface layers under non- equilibrium conditions. We showed that a polymer/surfactant mixture behaved differently under dynamic conditions when the pH changed: in one case bulk aggregation reduced the surface activity but in another case it enriched the surface excess due to a supplementary


was elucidated by a SANS experiment that provided evidence that within the micelles the iron ions were closely arranged. Now that this mechanism is known, the production of such soap on a large scale can be considered. Magnetic soap has also a potential application for drug encapsulation and targeted drug delivery to deliver medication where it is required without loss of the valuable


devices currently being developed at the ILL can benefit the engineering of soft material products and the optimisation of processing conditions. ❒


Dr Richard A Campbell is with Institut Laue-Langevin, Grenoble, France. www.ill.eu


REFERENCES 1 Campbell, Yanez Arteta, Angus- Smyth, Nylander & Varga, J. Phys. Chem. B, 2012, 116, 7981; 2 Angus-Smyth, Bain, Varga & Campbell, Soft Matter, 2013, 9, 6103; 3 Brown, Bushmelev, Butts, Cheng, Eastoe, Grillo, Heenan & Schmidt, Angewandte Chem. Int. Ed. 2012, 51, 2414; 4 Lopez-Barron, Porcar, Eberle & Wagner, Phys. Rev. Lett. 2012, 108, 2583.


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