The strong interaction between polyelectrolytes and ionic surfactants can result in pronounced surface adsorption and the formation of surface multilayer structures. This results in important surface properties with potential applications in detergency and in soft lubrication. In this context polyethyleneimine, PEI, based polyelectrolytes are particularly attractive. For the PEI base polyelectrolytes the architecture and molecular weight of the polyelectrolyte are important factors. Furthermore ethoxylation can fine tune the interactions and enhance their properties. We request beam time to study the surface adsorption of anionic surfactants with an ethoxylated PEI which shows great potential, in order to understand the key factors required for optimised detergency.