Neutron reflectometry will be used to probe the scattering length density profile in tethered films of block copolymers grafted onto silicon substrates. The tethered polystyrene-poly(methyl methacrylate) (PS-PMMA) block copolymers have been designed to laterally microphase separate into a variety of nanostructures. The surface morphology can be imaged by atomic force microscopy, however depth profiling is required to fully probe the structure. This will be achieved via modelling of the scattering length density profile for the microphase separated structures (spheres, cylinders, lamellae). Selectively deuterated block copolymers will be used to enhance the information content for determination of scattering length density profiles.