OpticsMy first contact with the field of optics dates back to 2011, in Milan, during my bachelor thesis. My research topic was the dynamics of thermosensitive colloids, measured by a technique called Differential Dynamic Microscopy. Over the years I have been able to contribute to the development of this technique [1,7]. In addition, this experience was an opportunity to get in touch with light scattering, which I also developed my master thesis in Montpellier [1,4-6]. In particular, I studied the the microscopic dynamics in samples under shear, which required both experimental and theoretical and teoretical work aimed at optimizing the optical setup and the data analysis protocol [4,6,7]. More recently, my passion for optics led to the development of a novel optical technique called Dynamic Speckle Holography (DSH), allowing one to reconstruct microscopic 3D displacements on large sample areas. |
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RheologyMy thesis project aimed at detecting dynamic precursors of failure in soft materials. This implies the coupling of rheology and optics, which is challenging from both an optical and a mechanical point of view. Indeed, light scattering introduces constraints connected to optical accessibility that are not easily satisfied by commercial rheometers. For this reason, at the beginning of my thesis I designed, developed and tested a new shear cell [2] that I then used for most of my experiments [4-7]. |
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Colloidal and Soft Matter PhysicsMy PhD work focused mainly on a colloidal gel with a fractal structure [5]. Under a constant shear stress, this gel exhibits a power law creep eventually interrupted by delayed failure. We show that the gel undergoes a series of microscopic plastic rearrangements that largely precede the fracture and are undetectable by probing conventional structural quantities [4]. Moreover, the stroboscopic evolution of the gel under a cyclic perturbation repeated several times shows the appearance of irreversible plasticity as the shear amplitude increases beyond the linear regime. Towards the end of my PhD I studied the oscillatory yielding of a soft colloidal glass. In this case, our experiments indicate that yielding is a gradual process, where two modes of relaxation contribute to the observed dynamics. More recently, I got interested in the mechanical properties of hydrogel composites, and I'm starting a research project aimed at unveiling the origin of Payne effect in model composite materials. |
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Fracture DynamicsDuring my postdoc at Harvard I got interested in fracture dynamics, and in particular in how fractures develop and interact in poroelastic materials. More specifically, I want to understand how the local deformation induced by the fracture propagation is affected by the heterogeneities of the material, and how in turn this affects the propagation of the fracture. |
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References
[1] A. Philippe, S. Aime, V. Roger, R. Jelinek, G. Prévot, L. Berthier, and L. Cipelletti, J. Phys.: Condens. Matter 28 (2016) 075201
[2] S. Aime, L. Ramos, J.M. Fromental, G. Prévot, R. Jelinek, and L. Cipelletti, Rev. Sci. Instrum. 87 (2016) 123907
[3] S. Aime, N. Eisenmenger, and T. Engels, J. Rheol. 61 (2017) 1329
[4] S. Aime, L. Ramos, and L. Cipelletti, PNAS 115 (2018) 3587
[5] S. Aime, L. Cipelletti, and L. Ramos, J. Rheol. 62 (2018), 1429
[6] S. Aime, and L. Cipelletti, Soft Matter 15 (2019) 200
[7] S. Aime, and L. Cipelletti, Soft Matter 15 (2019) 213