A light-driven flying balloon composed of carbon nanotube freestanding films

We have created a light-driven flying balloon composed of multi-walled carbon nanotube (MWNT) freestanding films. The balloon was fabricated by bonding the MWNT films, of which the thickness and density were approximately 6 μm and 0.5 mg cm−2, respectively. We found that water can be used as a glue for bonding the MWNT films. The MWNT films with and without bonding showed similar Young's modulus and gas permeability. We confirmed that the temperature of the balloon rapidly increased under light irradiation by virtue of the nearly perfect light absorption. As a result, the balloon levitated like a hot-air balloon.