Santa Barbara Amorphous-15

Typical SBA-15 powder sample

SBA-15, an acronym for Santa Barbara Amorphous-15, is a silica-based ordered mesoporous material that was first synthesized by researchers at the university of California Santa Barbra in 1998. ^[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:

The gel obtained in the second synthesis phase.

1. Solution preparation — Pluronic P123 is dissolved in an acidic solution of water at specific molar ratios ^[6] and the silica precursor typically TEOS or TMOS (sometimes EGMS ^[7] ) is added and mixed in for some time.
2. Hydrothermal treatment — The solution is sealed in a container and subjected to a temperature T1 for about 24 hours and then a higher temp T2 for 48 hours.
3. 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

The interest in SBA-15 comes from the fact that its mostly mesoporous – meaning the pores are in the range of 2 nm to 50 nm according to the IUPAC definition ^[8] and the fact that these pores have a well defined structure that is cylindrical shape in hexagonal ordering with their relatively thick pore walls which gives thermal stability. ^[9]

The sorption isotherms of these materials, demonstrate typical hysteretic behavior, which is still under discussion for its causes. ^[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, is directly related to the lattice parameter.

${\displaystyle q_{hk}={\frac {4\pi }{a{\sqrt {3}}}}{\sqrt {h^{2}+k^{2}+hk}}}$

where h and k are the miller indices.

• 
  TEM of a typical SBA-15 sample ^[10]
• 
  Demonstration of the hexagonal structure of SBA-15.
• 
  Small angle x-ray scattering pattern of a SBA-15 sample(data from Haidar et al.) ^[10]
• 
  Typical isotherm SBA-15 sample, data from Haidar et al. ^[10]

References

1. Zhao, Dongyuan; Feng, Jianglin; Huo, Qisheng; Melosh, Nicholas; Fredrickson, Glenn H.; Chmelka, Bradley F.; Stucky, Galen D. (1998-01-23). "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores" . Science. 279 (5350): 548–552. doi:10.1126/science.279.5350.548. ISSN   0036-8075. PMID   9438845.
2. Haidar, Ali F.; Belet, Artium; Goderis, Bart; Léonard, Alexandre F.; Gommes, Cedric J. (2024-08-20). "Small-Angle Scattering Indicates Equilibrium Instead of Metastable Capillary Condensation in SBA-15 Mesoporous Silica". Langmuir. 40 (33): 17444–17453. doi:10.1021/acs.langmuir.4c01609. hdl: 2268/321325 . ISSN   0743-7463. PMID   39110604.
3. Song, S.-W.; Hidajat, K.; Kawi, S. (2005-10-01). "Functionalized SBA-15 Materials as Carriers for Controlled Drug Delivery: Influence of Surface Properties on Matrix−Drug Interactions" . Langmuir. 21 (21): 9568–9575. doi:10.1021/la051167e. ISSN   0743-7463. PMID   16207037.
4. Lai, Yuan T.; Chen, Tse C.; Lan, Yi K.; Chen, Bo S.; You, Jiann H.; Yang, Chia M.; Lai, Nien C.; Wu, Jia H.; Chen, Ching S. (2014-11-07). "Pt/SBA-15 as a Highly Efficient Catalyst for Catalytic Toluene Oxidation" . ACS Catalysis. 4 (11): 3824–3836. doi:10.1021/cs500733j. ISSN   2155-5435.
5. Chen, Taipu; Chen, Lei; Zhao, Yutong; Hao, Jinkai; Shao, Zhigang (July 2024). "Organic phosphonic acid modified SBA-15 assisted enhanced high-temperature proton exchange membrane fuel cell performance of polybenzimidazole membranes" . Journal of Membrane Science. 707: 122948. doi:10.1016/j.memsci.2024.122948.
6. Cao, Liang; Man, Tiffany; Kruk, Michal (2009-03-24). "Synthesis of Ultra-Large-Pore SBA-15 Silica with Two-Dimensional Hexagonal Structure Using Triisopropylbenzene As Micelle Expander" . Chemistry of Materials. 21 (6): 1144–1153. doi:10.1021/cm8012733. ISSN   0897-4756.
7. Belet, Artium; Léonard, Alexandre; Heinrichs, Benoit (2024-05-13). "Small-angle scattering and sorption data in SBA-15 materials". dataverse. doi:10.58119/ULG/L8PJJK . Retrieved 2024-05-13.
8. Thommes, Matthias; Kaneko, Katsumi; Neimark, Alexander V.; Olivier, James P.; Rodriguez-Reinoso, Francisco; Rouquerol, Jean; Sing, Kenneth S.W. (2015-10-01). "Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report)" . Pure and Applied Chemistry. 87 (9–10): 1051–1069. doi:10.1515/pac-2014-1117. ISSN   1365-3075.
9. Chaudhary, Vasu; Sharma, Sweta (June 2017). "An overview of ordered mesoporous material SBA-15: synthesis, functionalization and application in oxidation reactions" . Journal of Porous Materials. 24 (3): 741–749. doi:10.1007/s10934-016-0311-z. ISSN   1380-2224.
10. Haidar, Ali F.; Léonard, Alexandre; Gommes, Cedric J. (2024-05-13). "Small-angle scattering and sorption data in mesoporous materials". dataverse. doi:10.58119/ULG/S0HYHL . Retrieved 2024-05-13.