The solution morphology of RNA-brush complexes was investigated next. The most sensitive contrast to resolve the conformation RNA-brush complexes was the aqueous phase with contrast matched to Si (the SLD contrast between the Si and the aqueous phase is zero). In this medium, the reflectivity profiles have the highest sensitivity to the materials at the interface, including to the SLD of oligonucleotides (on average, we calculated that RNA oligonucleotides would display an SLD close to 3.2-3.8 × 10 -6 Å -2 , assuming a density of 1.62 g mL -1 ). In contrast, in D2O and H2O, the high swelling of brushes, associated water content and the pronounced gap of their SLD with that of PDMAEMA and PMETAI brushes led to the medium SLD dominating the reflection pattern and led to poor resolution of complex architectures.