Abstract:

Revealing the mechanisms of self-organized core-shell (C-S) structure in immiscible systems has drawn considerable attentions, however, the further and fundamental understanding from the point of view of phase-separated pattern remains extremely rare. In this work, by realizing two phase-separated patterns in transparent immiscible system, namely nucleation-growth and spinodal decomposition, their effects on radius of minority-phase droplet (MPD) were examined, and subsequently the effect on C-S structure was further determined. It was found that compared with MPDs produced via nucleation-growth, the MPDs via spinodal decomposition are much larger and easier to form a C-S structure. This is mainly because the larger MPDs can migrate faster and are earlier to reach the sample’s center. In addition, two pathways of core formation were observed during the formation of C-S structure: one evolves from a ring-like structure in the phase separation of spinodal decomposition; the other derives from the collision of numerous MPD at sample’s center. Such a difference is ascribed to the combination of different growth kinetics and the volume fractions of MPD. These findings might provide an in-depth insight into the C-S structure formation in immiscible systems.

Key words: Phase separation, Immiscible system, Nucleation, Spinodal decomposition, Core-shell structure