Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 28: Micro and Nano Fluidics III: Migration and flow
CPP 28.5: Vortrag
Donnerstag, 28. Februar 2008, 17:45–18:00, C 264
Droplet-Based Emulsion Microfluidics for Monodisperse Silica Particle Synthesis — •Venkatachalam Chokkalingam1, Boris Weidenhof2, Wilhelm F. Maier2, Stephan Herminghaus1, and Ralf Seemann1,3 — 1Max Planck Institute for Dynamics and Self-Organization, Goettingen, Germany. — 2Technical Chemistry, Saarland University, Saarbrücken, Germany. — 3Experimental Physics, Saarland University, Saarbrücken, Germany.
We explore the possibility to produce silica particles from sol-gel chemistry by means of droplet based microfluidics. Aqueous droplets containing tetramethoxysilane (TMOS), solution (A), and ammonia, solution (B), are formed using two individual production units. The droplet production is synchronized at a Y-junction to form regular pairs of droplets containing the solutions A and B, respectively. The sol-gel reaction is started by merging the individual droplets using either electrocoalescence or a geometrical constriction. Mixing within the coalesced droplets proceeds quite efficiently and the gelation time of the sol-gel solution is adjusted to be within few seconds such, that the gel is fully developed when the gel particles are collected outside the microfluidic device for subsequent drying and heat treatment. The resulting silica particles have a diameter of a few micrometers, only. Since the sol-gel process can be used to produce mixed oxides with tailored porosity and pore size, this controlled monodispersed particle production is of potential interest for a broad range of applications in heterogeneous catalysis. Moreover, different volumetric combinations of any two chemicals are a first step towards combinatorial chemistry.