Electrical and Mechanical Properties of Freestanding Membranes Consisting of Organically Cross-Linked Metal Nanoparticles: The Effect of Order and Disorder

• Applicant: Dr. Tobias Vossmeyer
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263968789

Freestanding nanomembranes are 2D-materials with typical thicknesses of ca. 1-100 nm, which are not attached to a solid substrate. Due to the broad variety of potential applications, ranging from flexible electronics and novel sensors or MEMS elements to highly efficient filters and biomedical products, such membranes have received significant attention, during the past few years. In this project electrically conductive nanomembranes consisting of covalently cross-linked gold nanoparticles will be prepared and characterized. Because the charge transport in these membranes relies on tunneling of charge carriers between neighboring nanoparticles, already subtle variations of the interparticle distances should cause significant changes in the conductivity of these materials. Thus, straining the membrane should be detectable with extremely high sensitivity by simple resistance measurements. However, taking into account the results of previous studies, it is expected that the sensitivity of the charge transport to strain is dictated by the degree of ordering of the particles. With respect to potential applications as MEMS components and sensing elements we will investigate to what extent order and disorder control the mechanical and mechano-electrical properties of these membranes. For this purpose we will develop a new method allowing us to prepare highly ordered and covalently crosslinked nanoparticle membranes. In these membranes covalent cross-linking is needed to provide the material with sufficient strength and durability. Thereafter, the mechanical properties and mechanoelectrical transduction of the membranes will be analyzed by static and dynamic deflection tests. In order to correlate the results with relevant structural features we will characterize the degree of particle ordering and its perturbation and reorganization under stress by in situ SAXS measurements. Finally, the generated datasets will be used to evaluate the potential of cross-linked nanoparticle membranes for applications as highly sensitive mechanoelectrical transducers ond novel MEMS elements.

• DFG Programme: Research Grants
• Participating Person: Dr. Andreas Meyer