This proposal is part of a collaboration between Oxford and Ulster Universities and Unilever, on the development of sustainable laundry detergents, using a blend of conventional surfactants and biosurfactants derived from new biotechnologies. It is the subject of a new EPSRC CASE award. The particular focus of this proposal is to improve our understanding of the interfacial properties of multicomponent biosurfactant / conventional surfactant mixtures. In this proposal we request neutron reflectivity beam time on INTER / SURF to make a detailed exploration of the surface adsorption behaviour of a mixture of the biosurfactant rhamnolipid with different conventional surfactants at the air-water interface, which are representative of multicomponent detergent based formulations.