INVESTIGADORES
CANDAL Roberto Jorge
artículos
Título:
Effect of synthesis conditions on the microstructure of TEOS derived silica hydrogels synthesized by the alcohol-free sol?gel route
Autor/es:
PERULLINI M.; JOBBAGY M.; BILMES S.A.; TORRIANI I.; CANDAL R.J.
Revista:
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2011 vol. 59 p. 174 - 180
ISSN:
0928-0707
Resumen:
Silica matrices synthesized from a pre-hydrolysis
step in ethanol followed by alcohol removal at low
pressure distillation, and condensation in water, are suitable
for encapsulation of biomolecules and microorganisms
and building bioactive materials with optimized
optical properties. Here we analyze the microstructure of
these hydrogels from the dependence of I(q) data acquired
from SAXS experiments over a wide range of silica concentration
and pH employed in the condensation step. From
the resulting data it is shown that there is a clear correlation
between the microscopic parameters?cluster fractal
dimension (D), elementary particle radius (a) and cluster
gyration radius (R)?with the attenuation of visible light
when the condensation step proceeds at pH\6. At higher
pHs, there is a steep dependence of the cluster density
(*RD-3) with the condensation pH, and non-monotonous
changes of attenuance are less than 20%, revealing the
complexity of the system. These results, which were obtained for a wide pH and silica concentration range,
reinforce the idea that the behavior of gels determined in a
restricted interval of synthesis variables cannot be extrapolated,
and comparison of gelation times is not enough for
predicting their properties