Carbon Aerogel The New Lightest Material

The lightest material ever made has been produced by a team of scientists in China, a Chinese university announced. The ultra-light substance, called carbon aerogel, has a density of 0.16 milligrams per cubic centimeter, Zhejiang University in China said in a statement. One sixth of the substance is air.

Carbon aerogel, made of granite and carbon nanotubes, can also absorb up to 900 times its own body weight, the university said. "Carbon aerogel is similar to carbon sponge in structure," professor Gao Chao, who headed the team of scientists, said in the statement. "When an aerogel of the size of a mug is put on Setaria, the slender grass will not bend." Chao said aerogel could provide solutions to problems such as pollution control and cleaning up oil spills.

First carbon aerogels were first developed in the late 1980s.

Carbon aerogels are composed of particles with sizes in the nanometer range, covalently bonded together. They have very high porosity (over 50%, with pore diameter under 100 nm) and surface areas ranging between 400–1,000 m2/g. They are often manufactured as composite paper: non-woven paper made of carbon fibers, impregnated with resorcinol–formaldehyde aerogel, and pyrolyzed. Depending on the density, carbon aerogels may be electrically conductive, making composite aerogel paper useful for electrodes in capacitors or deionization electrodes. Due to their extremely high surface area, carbon aerogels are used to create supercapacitors, with values ranging up to thousands of farads based on a capacitance of 104 F/g and 77 F/cm3. Carbon aerogels are also extremely "black" in the infrared spectrum, reflecting only 0.3% of radiation between 250 nm and 14.3 μm, making them efficient for solar energy collectors.

The term "aerogel" to describe airy masses of carbon nanotubes produced through certain chemical vapor deposition techniques is incorrect. Such materials can be spun into fibers with strength greater than Kevlar, and unique electrical properties. These materials are not aerogels, however, since they do not have a monolithic internal structure and do not have the regular pore structure characteristic of aerogels.(wiki)