Neutron reflectometry (NR) is a very powerful technique for the study of thin layers. It is able to measure composition, thickness and roughness and is a very penetrating technique. One of the drawbacks when using NR is the loss of phase information in going from real space to inverse, or q space. In order to develop the phase retrieval approach at ISIS we would like to use this technique to unambiguously probe the composition profile for ideal and more complex real polymeric systems with many layers. In this continuation proposal we are moving from simple single and bilayer systems to look at blends of solar cell polymers and block copolymer systems using this technique.