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Résumé |
Curved surfaces are ubiquitous in soft matter and biological systems: from virus capsids to coated droplets. The behaviour of liquids embedded on such surfaces is however not established: the structure at low temperature has been studied in some simple geometries (sphere, etc), but the dynamics has not really been studied.
> In this talk, I will describe a model of a liquid embedded on a curved surface of constant negative curvature: the hyperbolic plane.
> I will show that this system exhibits all the characteristics of a glassy system. In addition, it appears to be a good candidate to be a benchmarking system to test the different theories of the glass transition and the recent methods proposed to extract a structural correlation length in glassy systems.
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> The second part of my talk will be dedicated to address the following question: Is the dramatic viscous slowing down encountered in glassy systems associated with the growth of some static amorphous order? This fundamental question remains unanswered for two main reasons: First, the nature of the hypothetical order has not been firmly established, and second, the experimental implementation of the various proposals is unclear.
> Recently, a generic method to define and quantify order has been proposed. Roughly, it consists of measuring the configurational entropy of patches (local clusters of varying size) in the system, and studying its scaling with patch volume V to extract a correlation length.
> I will discuss the implementation of this new proposal on colloidal systems and on the model described above. The latter allows to validate the method by comparing it to other proposed measures.
> This new method can also be used to access the symmetries of the local order, without any a priori knowledge of it.
> I will also show first applications to experimental data (3D colloidal systems) allowing to access both order extension and symmetries.
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