Ultrathin layers of surface-attached polymer networks provide a robust and scalable pathway towards engineered material interfaces. We present a simple photochemical technique for fabricating structured polymer networks, enabling the construction of responsive surfaces with unique properties. The approach is based on the photo-cross-linking of copolymers synthesized from N-isopropylacrylamide and methacroyloxybenzophenone (MaBP). In order correlate layer swelling to the MaBP content, we have studied the swelling behavior of such layers in contact with aqueous solutions with both multiple-angle ellipsometry and neutron reflection.