Séminaire

Lundi 7 Octobre 2024 à 11h00.

Phase separation: From simple liquids to complex soft matter

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Phase separation is a fundamental phenomenon with wide-ranging implications in fields such as biology, geology, materials science, and industry, playing a critical role in creating spatially heterogeneous material distributions. In conventional phase separation, the minority phase typically forms droplets, which coarsen through mechanisms like Marangoni effects [1]. However, in viscoelastic phase separation (VPS) [2,3], the minority phase can form network or porous structures, particularly in mixtures where the components exhibit large mobility differences—a common feature in soft and biomaterials. Our investigation reveals a novel coarsening law governing VPS in colloidal suspensions, characterized by the growth pattern ℓ ∼ t1/2 for the characteristic domain size (ℓ) [4]. In contrast, VPS in polymer solutions lacks self-similar growth due to stress accumulation within transient polymer networks [2,3,5]. We find that domain coarsening in both scenarios is constrained by the mechanical relaxation of slow-component-rich phases. These insights have important implications for fields ranging from porous material formation to biological phase separation [6]. This work was supported in part by Specially Promoted Research (JP20H05619) from the Japan Society for the Promotion of Science (JSPS).

[1] R. Shimizu and H. Tanaka, A novel coarsening mechanism of droplets in immiscible fluid mixtures, Nat. Commun. 6, 7407 (2015).
[2] H. Tanaka. Viscoelastic phase separation. J. Phys.: Condens. Matter, 12, R207–R264 (2000).
[3] H. Tanaka. Phase separation in soft matter: The concept of dynamic asymmetry. Soft Interfaces: Lecture Notes of the Les Houches Summer School, 98, 465–526 (2017).
[4] M. Tateno and H. Tanaka. Power-law coarsening in network-forming phase separation governed by mechanical relaxation. Nat. Commun., 12, 912 (2021).
[5] J. Yuan, M. Tateno, and H. Tanaka. Mechanical slowing down of network-forming phase separation of polymer solutions. ACS nano 17, 18025–18036 (2023).
[6] H. Tanaka, Viscoelastic phase separation in biological cells, Communications Physics 5, 167 (2022).

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