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Carbon Nanomembranes (CNMs)

Kolloquium der Abteilung 5

Carbon nanomembranes (CNMs) are extremely thin (~1nm), synthetic, two-dimensional (2D) layers or sheets with tailored physical, chemical or biological functions. With their two opposing surfaces they interface and link different environments with their distinct physical and chemical properties, which depend on their thickness, molecular composition, structure and the environment on either side. Due to their minute nanometer thickness and 2D architecture, they can be regarded as "surfaces without bulk" separating regions with different gaseous, liquid or solid components and controlling any materials exchange between them.

A universal scheme for the fabrication of functional CNMs is presented. Its first step is the formation of a monolayer of aromatic molecules on a solid surface. This precursor layer is exposed to electrons or UV, which leads to a dehydrogenation, followed by a cross-linking between neighboring molecules. The cross-linked monolayer is then released from the surface, forming a self-supporting CNM with properties that are determined by the precursor molecules. CNMs can then be further processed, for example, be perforated or have their surfaces functionalized. Pyrolysis transforms CNMs into graphene.  It will be shown that CNMs can be engineered with a controlled thickness, conductivity, permeability and elasticity. CNMs are also tested as ballistic membranes for the separation of gas molecules. Helium ion microscopy and spectroscopic methods as well as functional tests are applied to investigate the structure and composition as well as mechanical, electrical and optical properties of the CNMs. Technical applications of CNMs will be discussed.