The ability of the overlapping hBN sheets surrounding the dispersed aqueous to control diffusion across the interface was also demonstrated. Polymerizing the continuous oil phase produced polyHIPE hBN composite materials with significant flame-retardant properties. This robust method for hBN exfoliation polyHIPE synthesis opens the door for other applications of hBN. It provides a possible route to flame retardant polymers without using environmentally suspect chemical additives.