Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Colloids and Complex Liquids I

CPP 28.13: Vortrag

Mittwoch, 28. März 2012, 18:30–18:45, C 130

Small Angle Scattering applied to Phospholipid stabilized Colloidal Crystals — •Martin Schmiele, Mirijam Zobel, and Tobias Unruh — Lehrstuhl für Kristallographie und Strukturphysik, Staudtstraße 3, D-91058 Erlangen

Many routines do exist to simulate small angle scattering of dispersions of homogeneous nanoparticles, they all rely on the calculation of the particle form factor. However, dispersions of nanocrystals with long crystallographic c-axes may show Bragg peaks in the small angle range. With the existing routines, Bragg reflections can only be taken into account by heuristic models for the peak profiles. In order to compute small angle diffractograms from colloidal dispersions of nanocrystals the X-Ray Powder Pattern Simulation Analysis (XPPSA) has been developed. The XPPSA facilitates the computation of this scattering contribution directly from the crystals geometry. Application-related our group focuses on dispersions of tripalmitin nanocrystals stabilized with phospholipids in an aqueous dispersion medium. They can be considered as a representative model for many similar colloidal dispersions that are currently under discussion as potential drug delivery carrier systems. Revealing the molecular arrangement of the phospholipids at the interface between tripalmitin and the aqueous phase is vitally important to comprehend the stabilization mechanism and to control drug encapsulation. A preliminary study with the aid of the XPPSA utilizing SAXS gave no clear picture for the structure of the stabilizer layer. To remove this ambiguity, SANS experiments at different contrasts for the stabilizer layer were carried out.