Light-induced levitation of ultralight carbon aerogels via temperature control

Abstract

We demonstrate that ultralight carbon aerogels with skeletal densities lesser than the air density can levitate in air, based on Archimedes' principle, when heated with light. Porous materials, such as aerogels, facilitate the fabrication of materials with density less than that of air. However, their apparent density increases because of the air inside the materials, and therefore, they cannot levitate in air under normal conditions. Ultralight carbon aerogels, fabricated using carbon nanotubes, have excellent light absorption properties and can be quickly heated by a lamp owing to their small heat capacity. In this study, an ultralight carbon aerogel was heated with a halogen lamp and levitated in air by expanding the air inside as well as selectively reducing its density. We also show that the levitation of the ultralight carbon aerogel can be easily controlled by turning the lamp on and off. These findings are expected to be useful for various applications of aerogels, such as in communication and transportation through the sky.

Valorization of Starch to Biobased Materials: A Review

“…Micropores of carbon nanofibers and carbon nanotubes had dimensions ranging from 1.8 to 2.0 nm, whereas mesopores and macropores had diameters ranging from 2 to 250 nm. In addition, the specific surface area ranges from 164–186 m 2 /g [ 189 ]. Parameters such as skeletal density, refractive index, and the thermal conductivity of silica aerogels could be determined in silica aerogels.…”

Ultralight Single‐Walled Carbon Nanotube Aerogels for Low‐Frequency Sound Absorption

“…The hierarchical porous framework fabricated by a freeze-drying process using the growth of ice in the dispersion as a template produces ultralight and robust aerogels because it consists of strong SWCNT-CMC composite nanofiber networks. [32,33] The diameter of SWCNT-CMC composite nanofibers is smaller by more than an order of magnitude than that of microfibers fabricated by electrospinning, providing more opportunities for acoustic energy loss within the material. Furthermore, by confirming the consistency with the Biot-Johnson-Champoux-Allard (Biot-JCA) model, [34] which simultaneously considers the air-borne and solid-borne sound in the material, we showed that both the porous structure and elastic modulus of the framework of the ultralight SWCNT aerogel contribute to sound absorption.…”

Elastic Recovery Properties of Ultralight Carbon Nanotube/Carboxymethyl Cellulose Composites

“…In 2013, Sun et al reported a graphene aerogel with a density of 0.16 mg/cm 3 [ 21 ], which is approximately one sixth of air density and remarkably light. It has also been reported that ultralight aerogels with density less than air density can be levitated in air by controlling the temperature and selectively expanding the air inside the aerogel [ 22 ]. Such ultralight materials with ultimate lightness have the potential for further applications such as in communication and sky transportation [ 23 , 24 ].…”

“…In this study, we manufactured the ultralight materials with a density less than 5 mg/cm 3 by compositing single-walled CNT and sodium carboxymethyl cellulose (CMC) using freeze-drying. Single-walled CNTs facilitate the fabrication of materials in the density range approaching air density due to their high aspect ratio and mechanical properties [ 22 ]. CMC was used as dispersant [ 32 , 33 ].…”