Synthesis of Aragonite Nanofilament Networks by Mesoscale Self‐Assembly and Transformation in Reverse Microemulsions

Remarkable doughnut‐shaped micrometer‐sized aragonite particles with mesoporous sponge‐like interiors (see Figure) are spontaneously assembled in water‐in‐oil microemulsions. The structures consist of an interlinked network of complex nanofilaments that arise from the surfactant‐mediated mesoscale transformation and crystallization of amorphous CaCO3 hybrid nanoparticles.