Relaxation dynamics of colloidal particles at liquid interfaces


Wang, A. ; Kaz, D. M. ; McGorty, R. ; Manoharan, V. N. Relaxation dynamics of colloidal particles at liquid interfaces. AIP Conference Proceedings, 2013, 1518, 336-343.


We study the dynamics of colloidal particles as they approach and breach a water-oil interface. We use a fast 3D imaging technique, digital holographic microscopy, to track particles with 2 nm precision and sub-millisecond time resolution. We find that polystyrene particles dispersed in water or water-glycerol mixtures relax logarithmically with time after breaching the interface and do not reach equilibrium on experimental timescales. By contrast, decane-dispersed PMMA particles show fast dynamics and reach a steady-state height within milliseconds. We attribute the difference to the surface properties of the particles. We also probe the dependence of the relaxation rate on surface charge by studying carboxyl-functionalized particles under varying acid concentrations. We conclude that the slow relaxation may be due to contact-line pinning on topographical defects rather than surface charges.


Presented at 4th International Symposium on Slow Dynamics in Complex Systems in Sendai, Japan

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Last updated on 03/26/2016