Hydrophobic aerogels

Summary Hydrophobic aerogels were prepared by base-catalyzed hydrolysis and condensation of RSi(OMe)3 (R = Me, Ph, PrI1)/Si(OMe)4 (1 4) mixtures in methanol, followed by supercritical drying of the obtained alcogels with methanol. The organic substituents also increase the elasticity of the aerogels. 

Schwertfeger F, Glaubitt W, Schubert U. Hydrophobic aerogels from Si(OMe)4/MeSi(OMe)3 mixtures. J Non-Cryst Sohds. 1992 145 85-9. 

Begag R, Fesmire JE, Sorm JH (2(X)8) Nmillanimable, hydrophobic aerogel composites for cryogenic applications. Thermal Ctmd 29 323-333... 

In this chapter, we present a review of the s) thesis techniques for, properties of and applications of hydrophobic silica aerogels. In the following section, we review the techniques used to make silica aerogels. This is followed by sections devoted to the fabrication of hydrophobic aerogels, techniques for measuring hydrophobicity, a review of the literature on hydrophobic silica aerogels, and a summary of application areas for hydrophobic aerogels. 

Figure 3.4. Schematic illustration of the methoxylation method of preparing hydrophobic silica aerogels. The precursor chemical, solvent, catalyst (and water) are mixed in solution and allowed to gel and age. The aged wet gel is then dried (typically through CSCE) and the resulting aerogel undergoes a methoxylation process in a reactor at high temperature to form a hydrophobic aerogel.

Figure 3.5. Schematic illustration of the co-precursor method of preparing hydrophobic silica aerogels. The hydrophobizing co-precursor is added to the liquid solution, the solution is allowed to gel and then the wet gel is dried by a CSCE, ASCE, or RSCE technique which results in a hydrophobic aerogel.

Fesmire, J (2006) Aerogel insulation systems for space launch applications. Cryogenics 46(2-3) 111-117. Gougas, A, lUe, D, lUe, S, Pojidaev, V (1999) Behavior of hydrophobic aerogel used as a Cherenkov medium. Nucl Instrum Methods Phys Res, Sect A 421(1-2) 249-255. 

Lee, KH, Kim, S Y, Yoo, K1 P (1995) Low-density, hydrophobic aerogels. J Non-Cryst Sohds 186 18 22. Smirnova, 1, Suttiruengwong, S, Arlt, W (2004) FeasibUity study of hydrophihe and hydrophobic sUica aerogels as drug dehvery systems. J Non-Cryst Sohds 350 54-60. 

Schwertfeger, F, Glaubitt, W, Schubert, U (1992) Hydrophobic aerogels from Si (OMe)/MeSi (OMe) mixtures. J Non-Ciyst Sohds 145 85-89. 

Rao, A V, Pajonk, G, Haranath, D (2001) Synthesis of hydrophobic aerogels for transparent window insulation applications. Mater Sci Technol 17(3) 343-348. 

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

Reynolds, J G, Coronado, P R, Hrubesh, L W (2001) Hydrophobic aerogels for oil-spill cleanup-intrinsic absorbing properties. Energy Sources 23 831-834. 

Li, X M, Reinhoudt, D, Crego-Calama, M (2009) What do we need for a superhydrophobic surface A review on the recent progress in the preparation of superhydrophobic surfaces. Chem Soc Rev 36 1350 1368. Rao, A V, Kulkami, M M, Bhagat, S D (2(X)5) Transport of liquids using hydrophobic aerogels. J Colloid Interface Sci 285 413-418. 

Reynolds J. G., Coronado P. R., Hrubesh L. W. Hydrophobic aerogels for oil-spill clean up - synthesis and characterization, J. Non-Cryst. Solids 292, 127-137 (2001)... 

Yokogawa H, Takahama K, Yokoyama M, Uegaki Y (1992) Process for hydrophobic aerogel. US Patent No 5830387. 

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