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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster Session I

CPP 17.1: Poster

Monday, March 27, 2023, 18:00–20:00, P3

Plasmonic behaviour of surface modifications of γAlOOH nanoparticles and their effect on the particles Hamaker constant — •Dorothee Silbernagl¹, Mateusz Dudziak¹, Anna Maria Manzoni¹, and Heinz Sturm^1,2 — ¹Bundesanstalt für Materialforschung und -prüfung, Unter Den Eichen 87, 12205, Berlin, Germany — ²Institute for Machine Tools and Factory Operations (IWF), TU Berlin, Pascalstr. 8-9, 10587 Berlin, Germany

Boehmite (γAlOOH) nanoparticles (BNP, particle size appr. 14nm) are known for their extremely low Hamaker constant A, which results in low interparticle van der Waals forces. However, surface modified BNPs (modifications are acidic acid BNPA, lactic acid BNPL and stearic acid BNPS) exhibit a gradually increased Hamaker constant A and therefore increased interparticle van der Waals forces. This was measured by atomic force microscopy force distance curves (AFM FDC). For this experiment an unmodified BNP agglomerate of approximately 50um diameter was attached to an AFM cantilever and measured against pressed BNPs without and with different surface modifications. This set-up provides a sphere/plane geometry, necessary to calculate the Hamaker constant A of each material pairing from the FDCs attractive regime. Electron energy loss spectroscopy (EELS) measurements in the low energy region (up to 80eV) of unmodified and surface modified BNPs were performed to understand the origin of the increased van der Waals forces. As a result, additional plasmon bands were found in the region below 10eV for surface modified BNPs, which contribute to the attractive forces between particles.