PHD PHYSICAL CHEMISTRY, STARTING FALL 2016, BORDEAUX, FRANCE
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Porous materials towards gradient-index acoustic metamaterials
Metamaterials are artificial materials, which are structured at the mesoscopic scale and in which waves do propagate in a non conventional manner. Potential applications of these materials are numerous: planar lenses with sub-wavelength resolution, acoustic/optical cloaking, furtivity etc… The first experimental realizations were performed using hand-made mechanical methods [Science 289, 1734 (2000)] but it appeared that soft matter technologies could also be used to build materials with a colloidal scale structure [Science 342, 323 (2013)].
On the Bordeaux University campus, our teams (at CRPP, LOF and I2M) recently showed that acoustic 3D metamaterials could be obtained by suspending calibrated micrometric particles constituted by a porous organic (a silicone-based polymer) [Nature Mat. 14, 384 (2015)] or inorganic (silica particles) [Adv. Mat., in press 2016] material in a gel phase. We also showed that porous materials may exhibit a wide range of acoustic refraction index values from 1 up to 40, which are exceptionally large values. More precisely, we showed that the materials refractive index can be fully controlled by the level of porosity and the values of the solid part elastic moduli [Langmuir 31, 3215 (2015)].
In the team, we aim at spatially organizing the porosity of the material in order to obtain gradient index properties. Potential applications of such structures as ultra-thin attenuators, beam steerer or planar lens are expected. The goal of the thesis is to formulate these porous materials, using an emulsion-templating approach, and to measure their acoustic properties.
The formulation aspect of the thesis implies several steps that are the emulsification, size selection and colloidal stability control of the suspensions. Shaping of the systems and the control over the gradient properties will be performed using microfluidic techniques in strong collaboration with the LOF team (J. Leng). Acoustic properties measurements and comparisons to theoretical predictions will be achieved under the supervision of the I2M team (T. Brunet).
Nr of positions available : 1
Early stage researcher or 0-4 yrs (Post graduate)
First Stage Researcher (R1)
including health insurance and vacation days, as stated in the french law
|Degree||Master Degree or equivalent|
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