Materials Science

Spraying Nanoporous Silica

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Science  01 Jun 2001:
Vol. 292, Issue 5522, pp. 1613
DOI: 10.1126/science.292.5522.1613b

The production of nanoporous templated materials often requires a multistage process: A template for a particular microstructure is made from a colloid or block copolymer, the desired material is solidified around this template, and then the template material is burned away.

Iskandar et al. describe a simpler process that produces nanoporous silica with hexagonally packed 50-nanometer pores. Colloidal silica particles were mixed with polystyrene latex and then dissolved in water. An ultrasonic nebulizer was used to break up the solution into small droplets that were then sprayed into a two-stage furnace. In the first stage, the water was evaporated, and in the second, hotter stage, the polystyrene was driven off, all within several seconds. Increasing the concentration of the polystyrene latex particles initially improves the porosity of the silica, but high concentrations lead to silica particles that are fractured and very brittle. With such a simple production method, it is envisioned that nanoporous silica will find use in areas ranging from catalysis to pigments to electronics. — MSL

Nano Lett. 1, 231 (2001).

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