Relaxation rate of the shape fluctuation of a fluid membrane immersed in a near-critical binary fluid mixture

. We consider the two-time correlation of the shape fluctuation of a fluid membrane immersed in a near-critical binary fluid mixture. Usually one component of the mixture is preferably attracted by the membrane. Adsorption layers, where the preferred component is more concentrated, are generated on...

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Bibliographic Details
Published in:The European physical journal. E, Soft matter and biological physics Soft matter and biological physics, 2016-03, Vol.39 (3), p.31-31, Article 31
Main Author: Fujitani, Youhei
Format: Article
Language:English
Subjects:
Adsorption
Biological and Medical Physics
Biophysics
Cell Membrane - chemistry
Complex Fluids and Microfluidics
Complex Systems
Hydrodynamics
Immersion
Kinetics
Linear Models
Membrane Fluidity
Nanotechnology
Physics
Physics and Astronomy
Polymer Sciences
Regular Article
Soft and Granular Matter
Surfaces and Interfaces
Thin Films
Viscosity
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Summary:. We consider the two-time correlation of the shape fluctuation of a fluid membrane immersed in a near-critical binary fluid mixture. Usually one component of the mixture is preferably attracted by the membrane. Adsorption layers, where the preferred component is more concentrated, are generated on both sides of the membrane significantly because of the near-criticality. The resultant gradient of the local mass-density difference between the two components generates additional stress, including the osmotic pressure, to influence the membrane motion. Assuming the mixture to be in the homogeneous phase near, but not too close to, the demixing critical point, we use the Gaussian free-energy functional to calculate the relaxation rate for a wavelength much longer than the correlation length of the mixture. Our calculation supposes weak preferential attraction and weak dependence of the mixture viscosity on the mass-density difference, and is performed within the linear approximation with respect to the undulation amplitude. It is shown for small wave number that the additional stress makes the relaxation more rapid independently of whether the preferred component is more viscous or not and that the relaxation rate can be regarded as proportional to the wave number even for a tensionless membrane. This linear dependence comes from the balance between the frictional force due to the mixture viscosity and the restoring force of the adsorption layer. Graphical abstract
ISSN:1292-8941
1292-895X
DOI:10.1140/epje/i2016-16031-8