Dynamics of colloidal aggregation in microgravity by critical Casimir forces

Abstract

Using the critical Casimir force, we study the attractive-strength dependence of diffusion-limited colloidal aggregation in microgravity. By means of near field scattering we measure both the static and dynamic structure factor of the aggregates as the aggregation process evolves. The simultaneous measurement of both the static and dynamic structure factor under ideal microgravity conditions allows us to uniquely determine the ratio of the hydrodynamic and gyration radius as a function of the fractal dimension of the aggregate, enabling us to elucidate the internal structure of the aggregates as a function of the interaction potential. We find that the mass is evenly distributed in all objects with fractal dimension ranging from 2.55 for a shallow to 1.75 for the deepest potential.

5 pages, 4 figures

References in corpus (2)

• Casimir-like forces at the percolation transition
• Critical Casimir forces and colloidal aggregation: A numerical study

Cited by in corpus (5)

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• Sign change in the net force in sphere-plate and sphere-sphere systems immersed in nonpolar critical fluid due to the interplay between the critical Casimir and dispersion van der Waals forces