Solute effects on dynamics and deformation of emulsion droplets during freezing

• Published in: Soft Matter
• Main Authors: Tyagi, Sidhanth, Monteux, Cécile, Deville, Sylvain
• Other Authors: laboratoire de synthèse et fonctionnalisation des céramiques (LSFC), SAINT-GOBAIN-Centre National de la Recherche Scientifique (CNRS), Sciences et Ingénierie de la Matière Molle (UMR 7615) (SIMM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Liquides et interfaces (L&I), Institut Lumière Matière Villeurbanne (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SPI.MAT]Engineering Sciences [physics]/Materials; [CHIM.MATE]Chemical Sciences/Material chemistry; Sea ice
• Online Access: https://hal.archives-ouvertes.fr/hal-03274394; https://hal.archives-ouvertes.fr/hal-03274394v2/document; https://hal.archives-ouvertes.fr/hal-03274394v2/file/Solute_effects_on_dynamics_and_deformation_of_freezing_droplets%20%281%29.pdf; https://doi.org/10.1039/D2SM00226D

International audience Soft or rigid particles, suspended in a liquid melt, interact with an advancing solidification front in various industrial and natural processes, such as fabrication of particle-reinforced-composites, growth of crystals, cryopreservation, frost heave, and growth of sea ice. The particle dynamics relative to the front determine the microstructure as well as the functional properties of the solidified material. The previous studies have extensively investigated the interaction of foreign objects with a moving solid-liquid interface in pure melts while in most real-life systems, solutes or surface active impurities are almost always present. Here we study experimentally the interaction of spherical oil droplets with a moving planar ice-water interface, while systematically increasing the surfactant concentration in the bulk liquid, using in situ cryo-confocal microscopy. We demonstrate that a small amount of surfactant in the bulk liquid can instigate long-range droplet repulsion, extending over a length scale of 40 to 100µm, in contrast to the short-range predicted previously (<1µm). We report on the droplet deformation, while they are in contact with the ice-water interface, as a function of the bulk surfactant concentration, the droplet size, and the crystal growth rate. We also depict the dynamic evolution of solute-enriched premelted films (~5µm). Our results demonstrate how an increasing concentration of surfactant in the bulk and its subsequent segregation during solidification can dramatically alter the solidification microstructures. We anticipate that our experimental study can serve for the development of theoretical models incorporating solute effects.