Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Nanoparticles and Composite Materials I (joint session CPP, BP)

CPP 3.1: Talk

Monday, March 16, 2015, 09:30–09:45, C 243

Iron Oxide Nancube Monolayers at the Air/Water Interface: Self-Organization on Nano- and Mikroscale — •Heiko Ahrens¹, Sarah Mehdizadeh Taheri², Thomas Ortmann¹, Andreas Gröning¹, Stephan Förster², and Christiane A. Helm¹ — ¹Physik, Uni Greifswald, 17487 Greifswald, Germany — ²Physikalische Chemie I, Uni Bayreuth, 95440 Bayreuth, Germany

Monodisperse Cubic Iron Oxide nano particles (5-8 nm) covered in oleic acid form stable films on the air water interface. Isotherms exhibit a plateau at 18 - 20 mN/m, then the pressure increases steeply. At zero surface pressure, Brewster angle microscopy(BAM)shows micrometer sized domains consisting of nanocubes immersed in a matrix of excess oleic acid. These small domains show Brownian motion. Then linear and mesh-like rigid domains (size 100 *m) are observed. The 5.5nm nanocubes form a homogenous monolayer in the plateau region, on further pressure increase large (100 *m) homogenous domains of bi- and even multilayer appear. The films of the larger 8 nm nanocubes remain heterogeneous at all surface pressures. Large (100 *m) patches of oleic acid monolayers coexist with medium sized (50*m) domains of particle monolayer and small domains (10 *m) of bi- and multilayers. All aggregation is irreversible.

These observations are confirmed by X-ray reflectivity and Grazing Incidence X-ray diffraction.