(264d) Generation of Monodisperse Ordered Mesoporous Materials from a Microfluidic Device

Surfactant-templated mesoporous materials are highly ordered materials containing uniform pores in the range of 2 - 50nm, thus finding a range of applications in catalysis, selective adsorption, separation, delivery, and electronics. Mesoporous particles of uniform size are of great interest due to their potential applications in non-conventional areas such as biosensors, biomolecule delivery, and micro devices.1 Despite their success, the previous synthesis methods such as a modified Stober and a spray drying methods still face technological challenges such as diversity of material choices and control of multi-functionality2 3. A recently-reported emulsion and solvent evaporation (ESE) method has several potential advantages over the previous methods.4 It is, however, still very difficult to control the size, the distribution of size, and the multi-functionality of the mesoporous silica particles. Microfluidic devices enable us to generate and manipulate emulsions, thus controlling the droplet size, the distribution of size, and the multi-functionality.5 Although the generation of monodisperse multi-functional polymer particles using microfluidic devices has attracted a great deal of research interest over the last decade, the synthesis of inorganic mesoporous materials using microfluidic devices has yet to be demonstrated. In this talk, we report a novel method to prepare monodisperse mesoporous silica particles with combining microfluidic generations of uniform droplets and subsequent solvent evaporation induced self-assembly (EISA). In this method, uniform droplets of inorganic precursor solution are first generated in the soft microfluidic devices. Mesoporous silica particles are then formed through self-assembly process induced by controlled solvent evaporation. We will talk about the important parameters affecting the formation of the monodisperse droplets of the ethanol-rich inorganic precursor solution. These parameters include the flow rates of precursor solution and oil, the relative amount of emulsifier in oil, the kinds of emulsifiers, and wetting characteristics of oil and inorganic precursor solution onto the soft microfluidic device. We will also report the control of the shape, the size, and the distribution of size of the mesoporous silica particles.

1 Jacinta C. Conrad Robert F. Shepherd, Summer K. Rhodes, Darren R. Link, Manuel Marquez, David A. Weitz, and Jennifer A. Lewis, Langmuir 22 (21), 8618 (2006). 2 Gabriel P. Lopez G. V. Rama Rao, Jaime Bravo, Hien Pham, Abhaya K. Datye, Huifang Xu, and Timothy L. Ward, Advanced Materials 14 (18), 1301 (2002). 3 Kazuhisa Yano and Tadashi Nakamura, Chemistry Letters 35 (9), 1014 (2006). 4 Bengt Kronberg Nina Andersson, Robert Corkery, and Peter Alberius, Langmuir 23 (3), 1459 (2007). 5 A.D. Stroock H.A. Stone, and A. Ajdari, Annual Review of Fluid Mechanics 36, 381 (2004).