title: Spontaneous dispersion of particles on liquid surfaces.
abstract: When small particles (e.g., flour, pollen, etc.) come in contact with a liquid surface, they immediately disperse. The dispersion can occur so quickly that it appears explosive, especially for small particles on the surface of mobile liquids like water. This explosive dispersion is the consequence of capillary force pulling particles into the interface causing them to accelerate to a relatively large velocity. The maximum velocity increases with decreasing particle size; for nanometer-sized particles (e.g., viruses and proteins), the velocity on an air-water interface can be as large as approximately 47 m/s. We also show that particles oscillate at a relatively high frequency about their floating equilibrium before coming to stop under viscous drag. The observed dispersion is a result of strong repulsive hydrodynamic forces that arise because of these oscillations.
authors.affiliation: Department of Mechanical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA. singhp@njit.edu
authors.forename: Pushpendra
authors.initials: P
authors.lastname: Singh
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Joseph
authors.forename: Sathish K
authors.initials: SK
authors.lastname: Gurupatham
authors.forename: Bhavin
authors.initials: B
authors.lastname: Dalal
authors.forename: Sai
authors.initials: S
authors.lastname: Nudurupati
mesh_terms: D000327:Adsorption; D008962:Models, Theoretical; D010316:Particle Size; D013499:Surface Properties; D013500:Surface Tension; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water