The neutron reflectometry data were fitted simultaneously for all contrasts by adjusting the SLD of the bulk media accordingly without changing any of the other parameters (Supplementary Figure and Table ). In agreement with previous literature, the hydration of brushes increased as a function of the position on the z-axis of the brush (perpendicular to the plane of the substrate, oriented towards the bulk solution). The roughness of the coatings reflected the swollen nature of the brushes and remained overall below half of the total thickness of the swollen brush coating .