This proposal is part of a new project which is a collaboration between Oxford, Newcastle, Ulster, and Unilever on the development of sustainable laundry detergents, using existing and new biotechnologies. It is the subject of a major grant from the UK dti technology programme. The particular focus of the programme that relates to this proposal is to improve our understanding of the solution and interfacial properties of biosurfactant / conventional surfactant mixtures. In this proposal we seek SANS beam time on LOQ to explore the solution self-assembly structure of rhamnolipid surfactants and, rhamnolipid / LAS surfactant mixtures, and this is part of the DPhil work of ML Chen.