Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 61: Interfaces and Thin Films I (joint session CPP/DY, organized by CPP)

CPP 61.1: Hauptvortrag

Donnerstag, 10. März 2016, 16:15–16:45, H51

Tuning of ordering in colloidal suspensions confined in thin films — Sebastian Schön¹, Yan Zeng¹, Sabine Klapp², and •Regine von Klitzing¹ — ¹TU Berlin, Institut für Chemie, Strasse des 17. Juni 124, 10623 Berlin — ²TU Berlin, Institut für Theoretische Physik, Hardenbergstraße 36, 10623 Berlin

Characteristic lengths of the structuring of silica nanoparticle suspensions confined between two silica surfaces were extracted from the oscillatory force profile of colloidal-probe atomic force microscopy (CP-AFM) measurements and compared with the bulk counterparts as obtained from structural peak of small angle X-ray scattering (SAXS). The wavelength λ extracted from CP-AFM correlates well with the mean particle distance 2π/qmax as obtained from SAXS structural peak. This observation suggests that there is no confinement effect on characteristic lengths themselves that represent the structuring, even though the confinement indeed induces a layered structure of the particles. A more quantitative study shows a relation of oscillatory wavelength of silica nanoparticle suspensions with the particle number density as λ=ρ-1/3, irrespective of particle size, surface charge of the particles and ionic strength of the solution. CP-AFM measurements on modified and deformable confining surfaces show an increase in amplitude with increasing surface potential and decreasing surface roughness and deformability. However, the corresponding wavelength remains unaffected. Current studies address the ordering of soft particles like thermosensitive nanogels in the confinement of thin films, where the inter particle interactions can be switched on and off.