Journal article
Formation of silica nanoparticles in microemulsions
Langmuir, Vol.23(6), pp.3017-3024
2007
Abstract
Silica nanoparticles for controlled release applications have been produced by the reaction of tetramethylorthosilicate (TMOS) inside the water droplets of a water-in-oil microemulsion, under both acidic (pH 1.05) and basic (pH 10.85) conditions. In-situ FTIR measurements show that the addition of TMOS to the microemulsion results in the formation of silica as TMOS, preferentially located in the oil phase, diffuses into the water droplets. Once in the hydrophilic domain, hydrolysis occurs rapidly as a result of the high local concentration of water. Varying the pH of the water droplets from 1.05 to 10.85, however, considerably slows the hydrolysis reaction of TMOS. The formation of a dense silica network occurs rapidly under basic conditions, with IR indicating the slower formation of more disordered silica in acid. SAXS analysis of the evolving particles shows that ∼11 nm spheres are formed under basic conditions; these are stabilized by a water/surfactant layer on the particle surface during formation. Under acidic conditions, highly uniform ∼5 nm spheres are formed, which appear to be retained within the water droplets (∼6 nm diameter) and form an ordered micelle nanoparticle structure that exhibits sufficient longer-range order to generate a peak in the scattering at q ≈ 0.05 Ã… -1. Nitrogen adsorption analysis reveals that high surface area (510 m 2/g) particles with an average pore size of 1 nm are formed at pH 1.05. In contrast, base synthesis results in low surface area particles with negligible internal porosity.
Details
- Title
- Formation of silica nanoparticles in microemulsions
- Authors
- K S Finnie (Author) - Australian Nuclear Science and Technology Organisation Materials DivisionJohn R Bartlett (Author) - Australian Nuclear Science and Technology Organisation Materials DivisionC J Barbé (Author) - Australian Nuclear Science and Technology Organisation Materials DivisionL Kong (Author) - Australian Nuclear Science and Technology Organisation Materials Division
- Publication details
- Langmuir, Vol.23(6), pp.3017-3024
- Publisher
- American Chemical Society
- Date published
- 2007
- DOI
- 10.1021/la0624283
- ISSN
- 0743-7463
- Organisation Unit
- School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland
- Language
- English
- Record Identifier
- 99448844202621
- Output Type
- Journal article
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- Web Of Science research areas
- Chemistry, Multidisciplinary
- Chemistry, Physical
- Materials Science, Multidisciplinary