Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 4: Colloids and Complex Fluids I (Joint Session BP/CPP/DY)
BP 4.3: Vortrag
Montag, 7. März 2016, 10:00–10:15, H45
Demixing and Ripening in Gradient Systems — •Christoph Weber1, Chiu Fan Lee2 und Frank Jülicher1 — 1Max Planck Institute for the Physics of Complex Systems, Dresden — 2Department of Bioengineering, Imperial College, London
Ostwald ripening in homogeneous mixtures is described by the Lifshitz-Slyozov theory. It captures the phenomenon of smaller droplets that shrink, while larger ones grow. This process is driven by a difference in the Laplace pressures between the drops. Recently, liquid-like drops have been reported in living cells, which ripen in a gradient of a regulating protein component. This protein is known to affect the phase separation properties along the gradient such that drops dissolve at one and grow at the opposite side of the cell. An open question is how an inhomogeneous background affects the ripening law in contrast to the homogeneous Lifshitz-Slyozov theory.
To this end we analytically derived the corresponding growth law using a mean field theory. We find that there is a gradient of supersaturation that leads to a drift and an inhomogeneous growth of drops. The latter gives rise to a dissolution boundary that moves through the system leaving droplets only at one side of the system.
Using our mean field approach to describe the interactions between multiple drops we discover that a larger gradient of supersaturation not necessarily implies a faster ripening. Instead, droplets can be spatially sorted in size leading an arrest of the ripening dynamics for large times until homogeneous Ostwald-ripening sets in again.