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Correlation of Secondary Particle Number with the Debye–Hückel Parameter for Thickening Mesoporous Silica Shells Formed on Spherical Cores
Mesoporous silica shells were formed on nonporous spherical silica cores during the sol–gel reaction to elucidate the mechanism for the generation of secondary particles that disturb the efficient growth of mesoporous shells on the cores. Sodium bromide (NaBr) was used as a typical electrolyte for t...
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| Published in: | ACS omega 2021-07, Vol.6 (27), p.17734-17740 |
|---|---|
| Main Authors: | , , , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Mesoporous silica
shells were formed on nonporous spherical silica
cores during the sol–gel reaction to elucidate the mechanism
for the generation of secondary particles that disturb the efficient
growth of mesoporous shells on the cores. Sodium bromide (NaBr) was
used as a typical electrolyte for the sol–gel reaction to increase
the ionic strength of the reactant solution, which effectively suppressed
the generation of secondary particles during the reaction wherein
a uniform mesoporous shell was formed on the spherical core. The number
of secondary particles (
N
2nd
) generated
at an ethanol/water weight ratio of 0.53 was plotted against the Debye–Hückel
parameter κ to quantitatively understand the Debye screening
effect on secondary particle generation. Parameter κ
a
, where
a
is the average radius of the
secondary particles finally obtained in the silica coating, expresses
the trend in
N
2nd
at different concentrations
of ammonia and NaBr.
N
2nd
was much lower
than that expected theoretically from the variation of secondary particle
sizes at a constant Debye–Hückel parameter. A similar
correlation with κ
a
was observed at the high
and low ethanol/water weight ratios of 0.63 and 0.53, respectively,
with different hydrolysis rate constants. The good correlation between
N
2nd
and κ
a
revealed that
controlling the ionic strength of the silica coating is an effective
approach to suppress the generation of secondary particles for designing
mesoporous shells with thicknesses appropriate for their application
as high-performance liquid chromatography column packing materials. |
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| ISSN: | 2470-1343 2470-1343 |
| DOI: | 10.1021/acsomega.1c02293 |