Santa Barbara Amorphous-15
Silica-based ordered mesoporous material
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Santa Barbara Amorphous-15 (SBA-15), is a silica-based ordered mesoporous material. It was first synthesized in 1998 by researchers at the University of California, Santa Barbara.[1] This material proved important for scientists in various fields, such as material sciences,[2] drug delivery,[3] catalysis,[4] fuel cells[5] and many other due to its desirable properties and ease of production.
Synthesis procedure
The procedure is a typical liquid crystal templating that consists of three steps:
- Solution preparation: The triblock copolymer Pluronic P123 is dissolved in an acidic aqueous solution. A silica precursor, such as tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS), is added to the solution and stirred.[6][7]
- Hydrothermal treatment: The solution is sealed in a container and subjected to a temperature T1 for about 24 hours and then a higher temperature T2 for 48 hours.
- Washing and calcination: The gel obtained from the previous step is washed with water and ethanol under centrifuging, and finally calcinated at about 550 °C for 6 hours.
Structure
SBA-15 possesses a mesoporous structure. According to the IUPAC definition, mesopores range from 2 to 50 nm in diameter.[8] In SBA-15, these pores are cylindrical and arranged in a hexagonal pattern aligning with its relatively thick pore walls, giving it thermal stability.[9]
The sorption isotherms of these materials demonstrate typical hysteretic behavior. The causes of this behavior is still under discussion.[2]
TEM
The transmission electron microscopy of the sample shows the cylindrical pores but also highlights the fact that the pores of this material exhibit geometric deformations.
SAXS
The small-angle X-ray scattering pattern shows typical Bragg peaks to the hexagonal structure of the material. The peak positions are directly related to the lattice parameter.
where h and k are the miller indices.
