Skip to main content
SpringerLink
Log in

Hydrophobic silica aerogels prepared via rapid supercritical extraction

  • Original Paper
  • Published:
Journal of Sol-Gel Science and Technology Aims and scope Submit manuscript

Abstract

Hydrophobic silica aerogels have been prepared using the rapid supercritical extraction (RSCE) technique. The RSCE technique is a one-step methanol supercritical extraction method for producing aerogel monoliths in 3 to 8 h. Standard aerogels were prepared from a tetramethoxysilane (TMOS) recipe with a molar ratio of TMOS:MeOH:H2O:NH4OH of 1.0:12.0:4.0:7.4 × 10−3. Hydrophobic aerogels were prepared using the same recipe except the TMOS was replaced with a mixture of TMOS and one of the following organosilane co-precursors: methytrimethoxysilane (MTMS), ethyltrimethoxysilane (ETMS), or propyltrimeth-oxysilane (PTMS). Results show that, by increasing the amount of catalyst and increasing gelation time, monolithic aerogels can be prepared out of volume mixtures including up to 75% MTMS, 50% ETMS or 50% PTMS in 7.5–15 h. As the amount of co-precursor is increased the aerogels become more hydrophobic (sessile tests with water droplets yield contact angles up to 155°) and less transparent (transmission through a 12.2-mm thick sample decreases from 83 to 50% at 800 nm). The skeletal and bulk density decrease and the surface area increases (550–760 m2/g) when TMOS is substituted with increasing amounts of MTMS. The amount of co-precursor does not affect the thermal conductivity. SEM imaging shows significant differences in the nanostructure for the most hydrophobic surfaces.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

References

  1. Pierre AC, Pajonk GM (2002) Chemistry of aerogels and their applications. Chem Rev 102:4243–4265

    Article  CAS  PubMed  Google Scholar 

  2. Akimov YK (2003) Fields of application of aerogels (review). Instrum Exper Tech 46(3):287–299

    Article  CAS  MathSciNet  Google Scholar 

  3. Miner M, Hosticka B, Norris P (2004) The effects of ambient humidity on the mechanical properties and surface chemistry of hygroscopic silica aerogel. J Non-Cryst Solids 350:285–289

    Article  CAS  ADS  Google Scholar 

  4. Rao AP, Rao AV, Bangi UKH (2008) Low thermal conductive, transparent and hydrophobic ambient pressure dried silica aerogels with various preparation conditions using sodium silicate solutions. J Sol–Gel Sci Technol 47(1):85–94

    Article  CAS  Google Scholar 

  5. Hüsing N, Schwertfeger F, Tappert W, Schubert U (1995) Influence of supercritical drying fluid on structure and properties of organically modified silica aerogels. J Non-Cryst Solids 186:37–43

    Article  Google Scholar 

  6. Martín L, Ossó JO, Ricart S, Roig A, García O, Sastre R (2008) Organo-modified silica aerogels and implications for material hydrophobicity and mechanical properties. J Mater Chem 18(2):207–213

    Article  CAS  Google Scholar 

  7. Yokogawa H, Yokoyama M (1995) Hydrophobic silica aerogel. J Non-Cryst Solids 186:23–29

    Article  CAS  ADS  Google Scholar 

  8. Lee KH, Kim SY, Yoo KP (1995) Low-density, hydrophobic aerogels. J Non-Cryst Solids 186:18–22

    Article  CAS  ADS  Google Scholar 

  9. Smirnova I, Suttiruengwong S, Arlt W (2004) Feasibility study of hydrophilic and hydrophobic silica aerogels as drug delivery systems. J Non-Cryst Solids 350:54–60

    Article  CAS  ADS  Google Scholar 

  10. Lee C, Kim G, Hyun S (2002) Synthesis of silica aerogels from waterglass via new modified ambient drying. J Mater Sci 37(11):2237–2241

    Article  CAS  Google Scholar 

  11. Rao AP, Rao AV, Pajonk GM (2005) Hydrophobic and physical properties of the two step processed ambient pressure dried silica aerogels with various exchanging solvents. J Sol–Gel Sci Technol 36(3):285–292

    Article  CAS  Google Scholar 

  12. Schwertfeger F, Glaubitt W, Schubert U (1992) Hydrophobic aerogels from Si(OMe)4/MeSi(OMe)3 mixtures. J Non-Cryst Solids 145:85–89

    Article  CAS  ADS  Google Scholar 

  13. Schwertfeger F, Hüsing N, Schubert U (1994) Influence of the nature of organic groups on the properties of organically modified silica aerogels. J Sol–Gel Sci Technol 2(1):103–108

    Article  CAS  Google Scholar 

  14. Rao AV, Haranath D (1999) Effect of methyltrimethoxysilane as a synthesis component on the hydrophobicity and some physical properties of silica aerogels. Microporous Mesoporous Mater 30(2–3):267–273

    CAS  Google Scholar 

  15. Rao AV, Pajonk GM (2001) Effect of methyltrimethoxysilane as a co-precursor on the optical properties of silica aerogels. J Non-Cryst Solids 285(1–3):202–209

    ADS  Google Scholar 

  16. Štandeker S, Novak Z, Knez Ž (2007) Adsorption of toxic organic compounds from water with hydrophobic silica aerogels. J Colloid Interface Sci 310(2):362–368

    Article  PubMed  CAS  Google Scholar 

  17. Reynolds JG, Coronado PR, Hrubesh LW (2001) Hydrophobic aerogels for oil-spill clean up––synthesis and characterization. J Non-Cryst Solids 292(1–3):127–137

    Article  CAS  ADS  Google Scholar 

  18. Hrubesh L, Coronado P, Satcher J (2001) Solvent removal from water with hydrophobic aerogels. J Non-Cryst Solids 285(1–3):328–332

    Article  CAS  ADS  Google Scholar 

  19. Roig A, Molins E, Rodríguez E, Martínez S, Moreno-Mañas M, Vallribera A (2004) Superhydrophobic silica aerogels by fluorination at the gel stage. Chem Comm 2004(20):2316–2317

    Article  CAS  Google Scholar 

  20. Gauthier BM, Bakrania SD, Anderson AM, Carroll MK (2004) A fast supercritical extraction technique for aerogel fabrication. J Non-Cryst Solids 350:238–243

    Article  CAS  ADS  Google Scholar 

  21. Gauthier BM, Anderson AM, Bakrania SD, Mahony MK, Bucinell RB (2008) Method and device for fabricating aerogels and aerogel monoliths obtained thereby. U.S. Patent 7,384,988. 10 June 2008

  22. Anderson AM, Wattley CW, Carroll MK (2009) Silica aerogels prepared via rapid supercritical extraction: effect of process variables on aerogel properties. J Non-Cryst Solids 355(2):101–108

    Article  CAS  ADS  Google Scholar 

  23. Roth TB, Anderson AM, Carroll MK (2008) Analysis of a rapid supercritical extraction aerogel fabrication process: prediction of thermodynamic conditions during processing. J Non-Cryst Solids 354(31):3685–3693

    Article  CAS  ADS  Google Scholar 

  24. Rao AV, Kulkarni M, Pajonk G, Amalnerkar D, Seth T (2003) Synthesis and characterization of hydrophobic silica aerogels using trimethylethoxysilane as a co-precursor. J Sol–Gel Sci Technol 27(2):103–109

    Article  CAS  Google Scholar 

  25. Fidalgo A, Ciriminna R, Ilharco LM, Pagliaro M (2005) Role of the alkyl-alkoxide precursor on the structure and catalytic properties of hybrid sol–gel catalysts. Chem Mater 17:6686–6694

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The Union College Aerogel Fabrication, Characterization, and Applications Laboratory has been funded by grants from the National Science Foundation (NSF MRI CTS-0216153, NSF RUI CHE-0514527, NSF MRI CMMI-0722842, and NSF RUI CHE-0847901), the American Chemical Society’s Petroleum Research Fund (ACS PRF 39796-B10), the Union College Faculty Research Fund and Union College Student Internal Education Fund. ECG received a Davenport Summer Research Fellowship from Union College. The SEM instrument was funded through grants from the National Science Foundation (NSF MRI 0619578) and New York State Assembly RESTORE-NY. The authors are grateful to Professor Brad Bruno for the use of the camera employed for contact angle measurements and helpful suggestions.

Author information

Authors and Affiliations

  1. Department of Mechanical Engineering, Union College, Schenectady, NY, 12308, USA

    Ann M. Anderson, Emily C. Green, Jason T. Melville & Michael S. Bono

  2. Department of Chemistry, Union College, Schenectady, NY, 12308, USA

    Mary K. Carroll & Emily C. Green

Authors
  1. Ann M. Anderson
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Mary K. Carroll
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Emily C. Green
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jason T. Melville
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Michael S. Bono
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Ann M. Anderson.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Anderson, A.M., Carroll, M.K., Green, E.C. et al. Hydrophobic silica aerogels prepared via rapid supercritical extraction. J Sol-Gel Sci Technol 53, 199–207 (2010). https://doi.org/10.1007/s10971-009-2078-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10971-009-2078-z

Keywords

Search

Navigation