Keywords: nucleation control, confinement, external field, crystallisation, polymorphism, metastable zone, microfluidics, nanotechnology, microdroplets
Nanotechnologies dedicated to nucleation control
This paper highlights the work of our group on the control and the observation of nucleation with techniques using nanotechnologies. This control is performed either by triggering nucleation in time with an external field or by localising it spatially in a microdroplet. Localisation in time using light irradiation induces nucleation by forming radicals; the use of electric field acts locally on the density of the solution. Localisation in space with a microfluidic device produces hundreds of nanovolume crystallisers where concentration and temperature are easily monitored. Thus, accurate statistical studies lead to the nucleation parameters (metastable zone, nucleation rate and polymorphism). Lastly, confinement with a microdroplet generator permits to reach very high supersaturations in fL to pL volumes allowing nucleation of a single crystal per microdroplet. All these methods clearly enhance nucleation in the metastable zone. Finally, they use small quantities of products offering potentialities for the screening of crystallisation conditions and phases (polymorphism).