Connectivity of elastic particles surrounding a liquid droplet: ultrasonic scattering analysis from Pickering emulsions to colloidosomes

Abstract Ultrasonic spectroscopy (US) analysis was performed on Pickering emulsions (PE), which are emulsions of solid particle-coated droplets, and colloidosome (CS) microcapsules with solid particles connected together. In the analysis of CS, in addition to the broad monopole and dipole peaks typical of US analysis of emulsions, a peak specific to elastic shells originating from resonant scattering was identified in the low-frequency region. This peak was also found to become more pronounced with increasing heat treatment. We also performed ultrasonic scattering analysis of the particle assembly supraball (SB), and succeeded in capturing the interconnection of primary particles within a single assembly by ultrasonic scattering, both in the case of CS and in the case of SB.