Freestanding non-covalent thin films of the propeller-shaped polycyclic aromatic hydrocarbon decacyclene
Alex van der Ham, Xue Liu, Dario Calvani, Adéla Melcrová, Melania Kozdra, Francesco Buda, Herman S. Overkleeft, Wouter H. Roos, Dmitri V. Filippov, Grégory F. Schneider
Abstract
Molecularly thin, nanoporous thin films are of paramount importance in material sciences. Their use in a wide range of applications requires control over their chemical functionalities, which is difficult to achieve using current production methods. Here, the small polycyclic aromatic hydrocarbon decacyclene is used to form molecular thin films, without requiring covalent crosslinking of any kind. The 2.5 nm thin films are mechanically stable, able to be free-standing over micrometer distances, held together solely by supramolecular interactions. Using a combination of computational chemistry and microscopic imaging techniques, thin films are studied on both a molecular and microscopic scale. Their mechanical strength is quantified using AFM nanoindentation, showing their capability of withstanding a point load of 26 ± 9 nN, when freely spanning over a 1 μm aperture, with a corresponding Young's modulus of 6 ± 4 GPa. Our thin films constitute free-standing, non-covalent thin films based on a small PAH.