When an entomologist dropped by 鈥檚 materials science lab at Newcastle University in the UK to borrow her electron microscope, 艩iller thought they would just be looking at some dragonfly wings to identify their species. But when she took a peek, she was taken aback by the wings鈥� resemblance to her own research.
鈥淲hen we looked at the dragonfly wings, we just wanted to classify them. But then we saw something that was much more interesting,鈥� she says. The wings were full of tiny pores, just like the aerogels 艩iller鈥檚 team studies.
Aerogels are some of the lightest materials in the world, and they鈥檙e surprisingly difficult to make. Now, 艩iller and her colleagues have developed a new method to make them inspired by the way baby dragonflies ready their jelly-like wings for flight.
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Dragonflies in their larval phase live underwater for as long as a few years. Eventually, they shed their larval skin to reveal soft, jelly-like wings. To dry out their wings, the dragonflies produce sodium bicarbonate in their hindgut and rectum. Then they fart it out, and it reacts with the water in their wings to create carbon dioxide, drying them out.
Propped up pores
The first step to creating an aerogel is making a jelly cube, which is a matrix of silica molecules full of pockets of water. There are various methods to remove the water and dry out the gel, leaving behind pockets of air. The result is a material so light that a chunk several centimetres across can聽balance atop a delicate flower without bending its petals.
To mimic the porous wings, 艩iller and her colleagues first added sodium bicarbonate to the jelly, which interacts with the water and another added chemical solvent to create carbon dioxide. That gas props up the pores so they don鈥檛 collapse. Then the material is rinsed and set out to dry for a day to produce the aerogel.
The final gels are comparable to those produced by other methods, which can be more labour-intensive and require specialised equipment, says at Union College in Schenectady, New York. 鈥淭hese look like they鈥檙e nice aerogel materials overall, and if aerogel-based products could be less expensive they would see much higher use,鈥� she says.
Space-age insulation
The materials used in this process cost about $4 per kilogram of aerogel produced, which 艩iller says is cheaper than other methods. Plus, she says, it doesn鈥檛 require the expensive equipment that many other methods need to dry aerogels at high temperatures and pressures.
Aerogels鈥� pores make it difficult for heat to move through them, so if they could be cheaply mass-produced they would make excellent insulation for homes, or even heat shielding for spacecraft.
鈥淎erogel insulation could save a lot of energy,鈥� says at Lawrence Livermore National Laboratory in California. He says that they could also be used like sponges to remove particulate pollution from the air or to clean up oil spills.
Advanced Materials
