Direct Three-Dimensional Observation of Phase Structures in a Non-aqueous Physical Gel by Synchrotron X-ray CT

A phase structure of a non-aqueous physical gel was speculated to be somewhat different from what is typically observed in binary liquid mixtures, e. g. the island-in-sea structure or bicontinuous structure. This is primarily because the conventional microscopy, scanning electron microscopy, and even laser scanning confocal microscopy offer structural information only at (or near) the surface and thus limited structural information can be obtained. High resolution X-ray computer tomography installed at SPring-8 was used to obtain threedimensional (3D) structure of the gel in non-destructive way. It was found for the first time that oil-containing cells were connected to make continuous oil-rich domains in the 3 D space (“microcellular porous structure”). This observation confirms the speculative model proposed in the previous study and also implies significance of dynamical asymmetry of the two components, i. e. oil and crystalline elastomer, during the gel formation processes.