Superparamagnetic iron oxide nanoparticles (SPION) are intensively researched for biomedical imaging, drug delivery, therapeutics and separation applications. Their functionality in such applications strongly depends on the density profile of the polymer shell grafted to the magnetic inorganic core. We have developed methods to synthesize SPION that are extremely monodisperse (SD<5%) and to which uniquely dense and stable polymer brush shells are grafted. Recently, we have made the first such SPION with polyoxazoline copolymer and topologically varied brush shells. These provide a new level of control over shell structure and thermal responsiveness. We will use SANS to investigate and verify the internal shell structure of ultra-monodisperse SPION with densely grafted polymer shells of defined sequence and varied monomer solubility, as well as their restructured shells upon changing of shell solvation due to heating.