Fabrication of rough colloids by heteroaggregation

Colloidal particles are normally considered to be topographically smooth and chemically uniform (down to the nanoscale). Nevertheless, surface heterogeneities do exist and have a strong impact on the particles' behaviour, especially at interfaces. Surface properties for instance define the wetting of colloids, a process not only of fundamental interest, but also highly relevant for applications, e.g. in the Pickering stabilization of emulsions and foams. In particular, the effect of surface roughness has recently gained increasing interest due to the potential of rough particles to stabilize emulsions and foams more effectively, as well as from a more fundamental point of view in relation to the generation of capillary forces useful for particle assembly. In this work, we present a synthetic pathway for the fabrication of all-silica model rough particles with tuneable and controlled surface roughness and surface chemistry over a broad size range. Additionally, the fabrication of raspberry-like particles with soft asperities is proposed. These experiments have the aim to provide clear, robust and straightforward approaches to realise model systems for the investigation of particle surface roughness-related issues in soft matter.