water interface. Such an embedded hBN flake is shown in Fig. , with a flake only partially adhered to the interface. The location of the hBN on the oil side of the oil: water interface resulted in sheets on the aqueous side of the interface being visible, while sheets on the oil side were fully embedded in the polymer matrix and could not be seen. Time also plays a role in our hBN emulsions. Unlike small molecule surfactants, hBN sheets exfoliate during the emulsion process. This exfoliation is not instantaneous; thus, the longer the mixing step, the more extensive the exfoliation. Fig. shows hBN polyHIPE samples homogenized for different times. Comparing Fig. and 5B shows that the surface of the hBN polyHIPE is affected by the draining of the emulsion. Larger spheres settled faster than smaller ones, so the bottom of the polyHIPEs contained larger cells. These larger cells had formed by the coalescence of smaller spheres that did not have enough hBN to stabilize them against coalescence, creating larger spheres with surfaces stabilized, but not saturated, with hBN. This can be seen in Fig. , where the areal density of hBN at the cell surface is significantly lower than in a smaller sphere closer to the top of the polyHIPE, as shown in Fig. . However, this difference disappeared if the emulsion was mixed for a longer time. The reason was that the exfoliation of the hBN requires the presence of a high-energy interface and takes a finite amount of time to spread. Mixing the oil and water phases produced a high-energy interface, but the interface had to be present long enough to give the hBN time to exfoliate. This did not happen in Fig. but did happen in the analogous Fig. .