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Droplet Based Microfluidics for Synthesis of Mesoporous Silica Microspheres

Published online by Cambridge University Press:  01 February 2011

Nick J. Carroll
Affiliation:
ncarroll@unm.edu, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
Svitlana Pylypenko
Affiliation:
spylypen@unm.edu, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
Amber Ortiz
Affiliation:
alortiz@unm.edu, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
Bryan Yonemoto
Affiliation:
byonemot@tulane.edu, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
Ciana Lopez
Affiliation:
ciana_la_rana@hotmail.com, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
Plamen Atanassov
Affiliation:
plamen@unm.edu, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
David A Weitz
Affiliation:
weitz@deas.harvard.edu, Harvard University, Engineering and Applied Science, Cambridge, Massachusetts, United States
Dimiter N Petsev
Affiliation:
dimiter@unm.edu, University of New Mexico, Chemical and Nuclear Engineering, Albuquerque, New Mexico, United States
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Abstract

Herein we present methods for synthesizing monodisperse mesoporous silica particles and silica particles with bimodal porosity by templating with surfactant micelle and microemulsion phases. The fabrication of monodisperse mesoporous silica particles is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. We show that hierarchically bimodal porous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes.

Type
Research Article
Copyright
Copyright © Materials Research Society 2010

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References

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