Solids go with the flow: A monodisperse flow in a microreactor provides an efficient method for keeping solid products away from channel walls. The use of a carrier phase, such as mineral oil, hexane, or toluene, enables solids to be synthesized without clogging of the reactor channels. Further injection points can be added to the microreactor to perform multistep syntheses (see picture).

The preparation of hierarchically structured organosilicon microcapsules from commercially available starting materials is described. Using a microfluidic device, an emulsion of dichlorodiphenylsilane is formed in a continuous phase of aqueous glycerol. The silane droplets undergo hydrolysis, condensation, and crystallization within minutes to form self-assembled, core-shell microcapsules. The microparticles have been characterized with light and electron microscopy, nuclear magnetic resonance spectroscopy (NMR), diffusion-ordered NMR spectroscopy (DOSY), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD). The characterization data show that the microcapsule walls consist of amorphous, oligomeric poly(diphenylsiloxane) surrounded by a spiny layer of crystalline diphenylsilanediol. Glycerol is occluded within the wall material but is not covalently bound to the silicon components. Glycerol is a crucial element for producing low-dispersity microcapsules with well-ordered surface spines, as the use of methyl cellulose as viscomodifier yields amorphous surfaces.

Feststoffe im Fluss: Eine monodisperser Fluss in einem Mikroreaktor bietet eine effiziente Möglichkeit, feste Produkte von Kanalwänden fernzuhalten. Mithilfe einer Trägerphase wie Mineralöl, Hexan oder Toluol lassen sich Feststoffe ohne Verstopfen der Reaktorkanäle synthetisieren. Durch weitere Einspritzpunkte kann der Mikroreaktor für den Einsatz bei mehrstufigen Synthesen präpariert werden (siehe Bild).