Recent advances in solid-phase organic synthesis are dramatically shrinking the materials gap between biopolymers and traditional polymers. Peptoids are a particularly promising bio-inspired polymer platform because of their highly efficient synthesis and ready availability of starting materials. The peptoid platform allows the systematic investigation of new materials that are intermediate between proteins and bulk polymers, in both their structure and their properties. Here we describe a family of peptoid sequences that fold into well-defined nanosheets that can display surface loops capable of specific molecular recognition. Such materials may become the basis for robust sensors for chem/bio detection.