SEM images of A) the top face (i.e., side of the film exposed to polymer solutions) of a 50-bilayer freestanding PEI/PVDMA film, B) the top face of a 100-bilayer freestanding PEI/PVDMA film, C) the bottom face (i.e., side of the film attached to the glass substrate) of a 100-bilayer freestanding PEI/PVDMA film, and D) a cross-section of a freestanding film (top face is pointing up, bottom face is pointing down). Scale bars = A–C) 1 µm and D) 2 µm.