Aerogel organic aerogels

Producing aerogel-like materials without supercritical drying at all preparation of inorganic—organic hybrid materials. ... 

The vapor-phase esterification of ethanol has also been studied extensively (363,364), but it is not used commercially. The reaction can be catalyzed by siUca gel (365,366), thoria on siUca or alumina (367), zirconium dioxide (368), and by xerogels and aerogels (369). Above 300°C the dehydration of ethanol becomes appreciable. Ethyl acetate can also be produced from acetaldehyde by the Tischenko reaction (370—372) using an aluminum alkoxide catalyst and, with some difficulty, by the boron trifluoride-catalyzed direct esterification of ethylene with organic acids (373). 

Transition-metal mixed oxides active in combustion catalysis have been prepared by two main procedures i) classical coprecipitation / calcination procedures starting from metal nitrates and/ or alkoxides ii) preparation based on the supercritical drying of gels prepared from organic complexes (alkoxides, acetylacetonates or acetates), producing aerogels . Details on the second preparation can be found in Ref. 13. 

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. 

Figure 8. Multiscale organization of carbon aerogels imaged by TEM. Example of the Ca(OH)2 based organic aerogel (Resorcinol/Catalyst - 45) heated at 1050°C.

Pekala RW. Organic aerogels from the polycondensation of resorcinol with formaldehyde J. Mat. Sci. 1989 3221-7. 

Pekala R.W., Alviso C.T., Kong F.M., Hulsey S.S. Aerogels derived from multifunctional organic monomers. J. Nn-Cryst Solids 1992 145 90-8. 

Pekala RW and F.M. Kong FM. A synthetic route to organic aerogels-mechanism, structure, and properties. Revue de physique appliquee. ColloqueC4, tome 24, avril 1989. 

Tamon H, Ishizaka H, Mikami M, Okazaki M. Porous structure of organic and carbone aerogels synthesized by sol-gel polycondensation of resorcinol with formaldehyde. Carbon 1997 35 791-6... 

Hybrid polymer-silica aerogels have exceptional insulating and mechanical properties and will soon be commercialized as high-performance, low-cost insulators.6 Inorganic-organic silica areogels are non-flammable... 

Organic aerogels, 1 750-752 Organically modified layered silicate (OMLS), 20 306, 307, 308 Organic archaeological materials,... 

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