Abstract

During the past decade, colloid-synthesis has greatly improved and particles with unprecedented complexity in terms of shape, compositions and interactions are now available. This opens new perspectives for many areas like micro-encapsulation, sensing, biomimetics or buildup of composite materials, but it as well poses new challenges for the characterization of particles. We focus on developing new tools for characterization of deformation- and interaction forces of colloidal particles on the single particle level. The combination of Atomic-Force Microscopy with optical microscopy techniques like micro-interferometry or fluorescence microscopy is particularly useful for this task.- Colloidal particles can be directly attached onto AFM cantilevers , allowing for precise measurements of forces acting on the particle as a function of displacement of the particle relative to a flat substrate. However in order to interpret this force-displacement data correctly in terms of mechanical or adhesion forces, additional information on shape changes of the particles is highly desirable. This can be achieved using in situ optical microscopy. We show how this technique can be used to “shed light” on the deformation of microcapsules like Polyelektrolyte Multilayer capsules [1, 2] or Pickering emulsion based systems [3, 4]. In the following, we introduce the “soft colloidal probe AFM ” which allows precise measurements of adhesion energies for soft matter surfaces [5].

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