Langmuir 2009, 25, 3919-3919
3919
Preface Neutron Reflectivity The articles in this special issue on neutron reflectivity cover a broad range of the applications of this technique and the related X-ray and neutron scattering experiments of SAXS, SANS, GISAXS, and GISANS. They deal not only with the characterization of surfaces and interfaces in the fields of soft matter and biology but also with the related issues of self-assembly and the relationship between these two aspects of colloidal systems. Many of the articles arise directly from a symposium held at the Institut Laue Langevin, Grenoble, France, during May 2008, entitled “Surfaces and Interfaces in Soft Matter and Biology: The Impact and Future of Neutron Reflectivity”. The symposium was held to honor the pioneering work and contribution of Bob Thomas (Oxford) in this field. In the past 20 or so years, neutron reflectivity has had a major impact on the characterization of surfaces and interfaces in the fields of soft matter and biology. The development of new instrumentation and neutron sources across the world heralds exciting new opportunities that exist to expand and exploit the applications of the technique further. The articles in this special issue demonstrate that impact, highlight Bob Thomas’s role, and importantly illustrate the exciting future directions. There are a number of striking themes that emerge from this collection of papers, which indicate the extent to which the technique has developed and provide insights into the future directions and developments. The study of complex multicomponent systems (surfactant mixtures, polymer/surfactant mixtures, and multicomponent biological assemblies) is commonplace. Complex surface structures, involving multilayers and other selfassembled surface structures, are frequently encountered. Grazing incidence diffraction and scattering (GISAXS and GISANS), reflectivity, and off-specular scattering are all being used to determine structures at surfaces both as a function of depth and in the plane of the surface or interface. These are now frequently complemented by related surface techniques such as Brewster angle microscopy and atomic force microscopy. Many of the articles feature this complementarity. A further indication of the level of complexity that can be investigated is the fact that a wide range of different surfaces/interfaces are now being probed,
including the air-water, liquid-solid (with a range of surface functionalities), and oil-water interfaces. Not just static structures but temporal effects are accessible, as well as a range of in situ studies (such as electrochemistry). A particularly striking feature of the articles for this special issue is the number devoted to different aspects of biology. The emphasis has moved from simply the characterization of phospholipid monolayers and bilayers to probing the nature of the interaction of different biological complexes, such as membrane proteins, lipoplexes, and cubosomes, with membranes and membrane surfaces. The significant expansion of the applications of the technique in this area is self-evident. There are a number of articles related to different aspects of self-assembly in a range of complex systems, including casein micelles, designer peptide nanostructures, and a variety of different mixed microstructures. These bulk scattering studies serve to emphasize the complementarity between the surface-specific and bulk scattering techniques and the importance of the interplay between the surface and bulk behavior. There are also some articles that are more technique-centered, but importantly, they show that the technique itself and not just its applications is still evolving in important directions associated with data collection, analysis, and interpretation. In summary, this special issue highlights a broad range of interesting science in soft matter and biology. It illustrates many of the directions of future applications and exploitation and shows what a rich legacy that the pioneering work of Bob Thomas and others has produced. Finally, it is entirely fitting that this special issue should be dedicated to the memory of Bob Rowell. Many of the authors in the broad field represented in this issue have greatly benefited from the exceptionally dedicated and professional service that Bob Rowell has given to Langmuir and the community that it serves. He will be greatly missed by us all. Jeff Penfold (on behalf of the symposium organizers A. R. Rennie, G. Fragneto, J. R. Lu, and S. Clarke).
10.1021/la9003824 CCC: $40.75 2009 American Chemical Society Published on Web 03/31/2009
LA9003824
