Manipulating Particle Size and Morphology of Mesoporous Silica
by Flow Synthesis
Tsz Nok Ng1, Kailin He1, King Lun Yeung1,2,*
1Department of Chemical and Biomolecular Engineering, 2Division of Environment, 3Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China
*Corresponding author: email@example.com
Microfluidic reactor offers a number of advantages for solid preparations. Early work on TiO2 and SiO2 demonstrated that a precise control of particle size can be obtained by simply changing the reaction time. Numerous metal nanoparticles have since been successfully prepared in microreactors. These synthesis were carried out under laminar flow, but the rapid heat transfer allows precise temperature control that enabled a direct control on the nucleation and growth of the nanoparticles. In this work, the precision by which fluid mixing, flow pattern, and reaction can be manipulated in a flow-synthesis reactor enables the deliberate preparation of ordered mesoporous silicas (OMS) of controlled particle size (ca. 50 to 650 nm) and shapes (i.e., spheres and random), as well as complex microstructures (i.e., hollow spheres). Fluid mixing and flow pattern were generated using Tee- and slit interdigital micromixers under laminar and Taylor flow conditions, while hydrolysis reactions was governed by the alkoxide precursors (i.e. TEOS & TMOS) and temperature. The hollow OMS spheres can host molecules and clusters as demonstrated by the incorporation of ferrocene and iron nanoparticles during their preparation.
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