How freezing affects morphology*

The solidification of liquids containing insoluble particles, whether rigid or soft, is a fundamental phenomenon with widespread relevance in both natural and industrial contexts. Investigating how the interplay of particle rejection and engulfment shapes the microstructure of the solidifying material is essential for numerous applications. In this presentation, we delve into the intricacies of this process using dilute oil-in-water emulsions and suspensions as experimental model systems, while gradually freezing them. We begin by showcasing how initially spherical oil droplets assume pointy, tear-like shapes during their incorporation into ice, with the extent of deformation being linked to the freezing rate. Shifting our focus to multi-component compound drops replacing the uniform oil droplets, we highlight the profound increase in complexity during the freezing process. Intriguingly, these compound drops undergo sudden topological transitions within the ice, leading to unanticipated local microstructural changes. Finally, we explore the interaction between neighboring particles at the ice interface. Surprisingly, we observe that particles with greater thermal conductivity than water exhibit attractive behavior and tend to form clusters once frozen, whereas less conductive particles tend to separate. Our research sheds light on the fascinating physics underlying the solidification of complex liquid systems, offering valuable insights for various practical applications.