Preface

Abstract

The subject of the present Special Issue is a hybrid of two areas:`liquids and soft matter' and `surfaces and interfaces', both ofwhich have special sections of Journal of Physics: CondensedMatter devoted to them. The topic `liquids at interfaces' is avery active area of research in physics as testified by thecollection of papers included in this Special Issue. These paperscontain both fresh research results and reviews of recentdevelopments in the field of inhomogeneous liquids.The basic challenge is to understand macroscopic properties ofliquid matter at interfaces on a `microscopic' scale, on the basisof either theories or computer simulations of models incorporatingthe microscopic interactions between the individual particles, or onthe basis of experimental studies which resolve the structural anddynamical correlation on a molecular~scale.The range of problems discussed under this heading is fairly narrow,comprising liquid films on substrates, near walls and in confininggeometries, as well as free liquid-solid and liquid-gasinterfaces. Interesting questions concern the thermodynamics,structure and dynamics of the free interfaces and phase transitionsnear interfaces and surfaces. A particular emphasis of the presentIssue is on wetting transitions near structured walls in differentsituations including wedges, periodically structured templates andcorrugated or decorated substrates. As documented by severalarticles, the resulting wetting scenarios are fairly complicated,depending sensitively on the substrate structure. Furthermore,dynamical issues are discussed, both for equilibrium and fornon-equilibrium situations, that are relevant to phase separation,crystal growth, conduction and drainage.On the other hand, the present Issue demonstrates that there is agreat diversification both of the systems investigated and themethods applied. The kinds of system investigated range frommolecular binary mixtures to supramolecular aggregates such aspolymers, colloidal suspensions, amphiphilic systems and biologicalsystems. Furthermore, even aspects of quantum fluids and foams aretouched upon.Among the broad range of methods applied are different theoreticalapproaches to model systems such as density functional theory,liquid integral equations and other more phenomenological methodsfrom statistical mechanics. Computer simulations provide anotherapproach used to resolve the liquid structure and dynamics on amicroscopic level. Last but not least, a wealth of differentexperimental techniques, such as neutron and x-ray reflectivity,atomic force and scanning tunnelling microscopy and the quartzcrystal microbalance technique, to name just a few, have beenapplied to extract precise data.As also documented by the present Issue, there has been significantprogress in our microscopic understanding of inhomogeneous liquidsachieved by combining and comparing these three complementaryapproaches of theory, computer simulation and experiment. Thissynergetic interplay will be exploited further in the near future,so a flourishing future can be expected for the physics of liquidsat interfaces.