(660f) Viscoelastic Characterisation of an Emulsion Drops Coating Via Capsule Compression

Characterising the viscoelastic properties of the interfacial films between oil and water has traditionally been done with interfacial rheological techniques such as bicone shear rheology, and pendant drop dilational rheology. These techniques characterise the behaviour of the interfacial film independent of the drop geometry in an emulsion or the impact of the film properties on drop interactions. We use colloidal probe Atomic Force Microscopy (AFM) to directly compress and dwell on individual emulsion droplets with viscoelastic coatings. The response to deformation of these drops exhibit viscoelastic relaxation behaviour more complicated than traditional interfacial rheological techniques. Through numerical modelling of the compression and relaxation process, we extract viscoelastic parameters of these films on the microscale and correlate this with traditional rheological techniques. We analyse an MCT oil/water interface covered by the whey protein, β-lactoglobulin, then crosslink this interface with glutaraldehyde to observe the changes in the interfacial film and rheological behaviour.