Abstract:
This work describes a versatile strategy for the formation of thixotropically reversible alumino-siloxane
hybrid gel suitable for the fabrication of open-porous aerogel like framework. Aminated alumino-siloxane gel was synthesized by pH controlled sol–gel assisted co-condensation of hydrolyzed aluminum isopropoxide with 3-aminopropyltrimethoxy silane. A rare reversible thixotropic flow behavior was noticed
for the first time in aminated alumino-siloxane hybrid gel. The hybrid gel was used for preparation of
hydrogel microspheres via gel granulation technique. The hydrogel microspheres derived from thixotropic gel showed an open porous network with intercommunicated structure. It was then converted to
aerogel microspheres, without the collapse of the transient hybrid porous network by ambient pressure
drying technique. The porous framework was tailored to hierarchical domains containing meso/macro
porosity, with a dense array of functional amine on internal porous framework. The textural properties
of the hybrid alumino-siloxane aerogel microspheres have been characterized by SEM, TEM, FTIR and
N2 gas adsorption/desorption analysis and the results are discussed. Hybrid aerogel microspheres exhibit
2–3 times superior properties in terms of surface area and pore features compared to their xerogel counterparts. Thus, open porous aerogel microsphere derived from thixotropic gel could be a new media for
controlling host–guest interactions especially when it is intended to be used in adsorption, separation
and catalysis/catalyst support.
