Monolithic aerogels

Fig. 5. Illustration of the diffusion limited activation in monolithic aerogel slices with different mesostructures.

Since the 1980s a new microporous insulation material based on silicic aerogels is in a test phase. About 60 years ago Kistler from Stanford University developed a method to produce aerogels from silicic material without shrinking them He reacted waterglass with hydrochloric acid, washed out the sodium and chloride ions from the gel, substituted the water with alcohol and dried the gel in an autoclave above the critical point. Other methods begin with tetramethoxysilane for the production of monolithic aerogels. 

A convenient way to avoid capillary forces is to perform supercritical drying. If the process is carried out carefully, a monolithic aerogel is obtained in a very short time (1 day). Moreover, the aerogel has a permeability much higher than that of its corresponding monolithic xerogel. 

Monolithic aerogels are often quite fragile. Describe two methods that can be employed to prepare stronger colloidal silica aerogels. Indicate how these methods might otherwise impact the native properties of the aerogel. 

Ilhan, U E, Eabrizio, E F, McCorkle, L, Scheiman, D A, Dass, A, Palczer, A, Meador, M B, Johnston, J C, Leventis, N (2006) Hydrophobic monolithic aerogels by nanocasting polystyrene on amine-modified silica. 

Ilhan U F, Fabrizio E F, McCorkle L, Scheiman D, Dass A, Palzer A, Meador M A B, and Leventis N, (2006) Hydrophobic Monolithic Aerogels by Nanocasting Polystyrene on Amine-Modified Silica. J Mater Chem... 

Figure 25.2. Photographs of a monolith aerogel iron (III) oxide/nanometric aluminum energetic composite that is shown with a penny for scale.

Ayers and Hunt constructed a sensor device using a mercury penlamp as the UV light source, a monolithic aerogel disk as the sensing platform, a cut-off filter to select for luminescence, and a photodiode detector. The response of the sensor to 1-760 Torr O2... 

Abstract American Aerogel produces an organic monolithic aerogel panel called Aerocore. Its properties have been optimized for the mass production of vacuum insulation panels (VIPs). This contribution summarizes the history of the company and describes the Company s materials. 

Kirkbir, F., Murata, H., Meyers, D., Chaudhuri, S. R., 1998b. Drying of large monolithic aerogels between atmospheric and supercritical pressures. J. Sol-Gd Sci. Techn. 13 311-316. 

Thermal transport in organic and opacified silica monolithic aerogels. Proceedings of 3rd International Symposium on Aerogels, J. Non-Cryst. Solids 145 ... 

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