(661g) Preparation of Silica Particles By Using of Slug Flow

In recent years there has been an increasing development in the field of microtechnology. The main reasons are (i) to provide well-defined reaction conditions, (ii) to save costly material and chemicals, (iii) to eliminate transport resistance and increase reaction rate, (iv) integration of several unit operation in a single microchip. One type of microfluidic devices are microsystems employing formation of regular segments of immiscible phases. Droplets of two immiscible phases form segments one and the other phase in microchannel. Droplets created in microfluidic devices are usually of uniform size and shape and can be used to form gel emulsions, colloidal particles, and complex geometric structures. Properties of produced capsules can be varied by the addition of micro-or nanoparticles in a dispersed phase.

Monodisperse silicon particles are prepared by EISA method (evaporation-induced self-assembly method). Size of the prepared particles is in the order of tens of micrometers (20-50 μm). Particle morphology is adjusted by mixing of reaction precursor with silicon particles with the diameter of about of 1 micron. The pore diameter of these microspheres is about 6 nm. In this way, we created a hybrid particles with a dual structure with characteristic dimensions  1 μm and  50 μm. With the use of slug flow, which produces droplets of the same size.  We can influence the concentration of  1 μm microspheres in the resulting hybrid particles by changing their concentration in the precursor.