>>On demand<< triggered crystallization of CaCO3 from solute precursor species

TL;DR

This study demonstrates how to control and trigger the crystallization of CaCO3 from supersaturated solutions within microemulsions, mimicking natural biomineralization processes using advanced in situ characterization techniques.

Contribution

We developed a method to control CaCO3 crystallization by confining reactions in nanosized water cores and triggering precipitation through interface removal, mimicking natural biomineralization.

Findings

CaCO3 forms and is stabilized inside micellar water droplets.

Crystallization can be triggered on demand by removing interfaces.

Advanced in situ techniques elucidate the crystallization process.

Abstract

Can we control the crystallization of solid CaCO3 from supersaturated aqueous solutions and thus mimic a natural process predicted to occur in living organisms that produce biominerals? Here we show how we achieved this by confining the reaction between Ca2+ and CO32- ions to the environment of nanosized water cores of water-in-oil microemulsions. Using a combination of in situ small-angle X-ray scattering, high-energy X-ray diffraction, and low-dose liquid-cell scanning transmission electron microscopy, we elucidate how the presence of micellar interfaces leads to the formation of a solute CaCO3 phase that can be stabilized for extended periods of time inside micellar water nano-droplets. We can also control and >>on-demand<< trigger the actual precipitation and crystallization of solid CaCO3 phases through the targeted removal of the organic-inorganic interfaces.