Per Ekwall and Physical Chemistry 1 in Lund: Ion binding and microstructure in relation to phase behavior

The research in the Department of Physical Chemistry 1 at Lund University includes topics such as surfactant self-assembly; polymers, solutions, gels and phase behavior, polymer-surfactant systems; protein and protein-amphiphile systems; adsorption and surface forces; experimental methodology in colloid science; and theory and modeling. (Annual Report (2004) Physical Chemistry 1; Lund University; Sweden.) How different research topics emerge is, of course, in many cases a complicated story and there are often long traces back. In this treatise, looking back on connections, we will demonstrate that early contacts with Per Ekwall have to a considerable extent influenced our research directions. As we will describe, the early contacts concerned experimental studies of ion binding in concentrated surfactant systems. These inspired further studies of ion binding in a range of colloid systems and these, in turn, theoretical work on electrostatic interactions. Per Ekwall and his coworker Krister Fontell also introduced us into the fascinating subject of cubic liquid crystals, which inspired us into the problem of connectivity versus discreteness of surfactant self-assemblies. Another significant aspect of the contacts with Per Ekwall and his group was that we learned the important role of phase diagrams in understanding surfactant systems. After analyzing briefly the early contacts we will exemplify some of our work on ion binding and on microstructure; aspects on phase diagrams are discussed by Hakan Wennerstrom in another article in this volume.