The present invention provides patterned features of dimensions of less than 50 nm on a substrate. According to various embodiments, the features may be "Manhattan" style structures, have high aspect ratios, and/or have atomically smooth surfaces. The patterned features are made from polymer brushes grafted to a substrate. In some embodiments, the dimensions of the features may be determined by adjusting the grafting density and/or the molecular weight of the brushes. Once the brushes are patterned, the features can be shaped and reshaped with thermal or solvent treatments to achieve the desired profiles. The chemical nature of the polymer brush is thus independent of the patterning process, which allows for optimization of the polymer brush used for specific applications. Applications include masks for pattern transfer techniques such as reactive ion etching.