Monolithic organic aerogels derived from single amino-acid based supramolecular gels: physical and thermal properties

Abstract : Highly porous materials have numerous applications in research field such as filtration and collection devices, catalysis, and electric devices or in acoustic and thermal insulation. In the later one, inorganic and / or macromolecular chemical gels, are extensively studied. Here, a new type of monolithic aerogel, made of self-assembled small organic molecules, is described. Those low-molecular weight aerogels (LMWA) are prepared from amino acids based (phenylalanine or leucine) supramolecular gels by using a CO2 supercritical drying process. The organogels and aerogels exhibit very interesting properties. Indeed, gelator molecules are able to immobilize aromatic solvents such as toluene or tetralin at low concentrations. Melting enthalpies (H) are calculated for both gelator molecules and for both solvents. In the case of aerogels, an important hydrophobic character, a very low density and remarkable thermal properties are observed. For the former one, measured contact angles are found between 110 and 114°. As for the second, those organic aerogels belong to the family of the lightest porous materials in the world with densities as low as 4.3 kg m-3. And finally, thermal measurements show that these LMWAs present a low thermal conductivity under atmospheric pressure (λ=26.5 mW·m-1·K-1) and very low thermal 20 conductivity under vacuum (λ=4 mW·m-1·K-1 at 10-2 mbar). Moreover, the measurement of the radiative conductivity demonstrated that LMWAs are a very scattering material; 80 to 90% of infrared radiations are stopped. Such characteristics make these materials viable candidates for use in thermal insulation
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Submitted on : Saturday, March 2, 2019 - 11:34:25 AM
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Brigitte Jamart-Gregoire, Sébastien Son, Florent Allix, Vincent Félix, Danielle Barth, et al.. Monolithic organic aerogels derived from single amino-acid based supramolecular gels: physical and thermal properties. RSC Advances, Royal Society of Chemistry, 2016, 6 (104), pp.102198-102205. ⟨10.1039/C6RA20803G⟩. ⟨hal-02054811⟩

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