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Séminaire Robert Hołyst

Diffusion and viscosity of complex fluids : from nano to macroscale


Robert Hołyst

Institute of Physical Chemistry
Polish Academy of Sciences, Warsaw

In a complex liquid consisting mostly of water small objects moving by diffusion feel the water viscosity while large objects experience orders of magnitude larger macroviscosity. We present experiments, where the viscosity is determined as function of the size of the diffusing object (sizes from 0.28 nm to 200 nm). We also determine a length scale over which the viscosity saturates at its macroscopic value.

Fluctuation-dissipation theorem is also checked in our experiments. The sharp (exponential) dependence of viscosity on the size of the object in a complex liquid in a nanoscale has important consequences for the diffusion limited reactions and also for transport in the living cells.