NASA scientists have devised a polymer aerogel that is at least 100 times stronger and more insulating than silica aerogels, a development that could lead to super-insulated clothing and buildings, unique filters, better insulation of pipes and water heaters, refrigerators with thinner walls, and even inflatable heat shields.
Once called “frozen smoke,” aerogels were invented in 1931 when two chemists challenged each other to remove water from pectin, a gelatin, without shrinking the volume. They are among the least dense solids and act as good insulators.
Traditional aerogels, however, made from silica, are brittle. The new aerogels, made with polymers, are strong, flexible, and hold up well against folding, creasing, and crushing, reports Gizmag.
“The new aerogels are up to 500 times stronger than their silica counterparts,” says Mary Ann B. Meador, a chemist at NASA’s Glenn Research Center in Ohio, where the development occurred. “A thick piece actually can support the weight of a car. And they can be produced in a thin form, a film so flexible that a wide variety of commercial and industrial uses are possible.”
How did the scientists make the new aerogels? At first they coated silica aerogels with polymers by using chemical vapor deposition, reports ZME Science. But the polymers that could be deposited using this method melted at low temperatures, making the aerogel unfit for most intended applications.
So the scientists took another route. They formed polymer aerogels that didn’t have any coating, forming them directly. ZME Science explains:
The team of researchers tried a cross-linking approach, where linear polyamides were reacted with a bridging compound to form a three-dimensional covalent polymer. The resulting density of the polymer aerogel was 0.14 g/cc, with 90% porosity. Silica gels were made with much better specs, but the polymer more than makes up for scale in strength.
These three-dimensional covalent polymers are more stiff than linear polymers, much like an I-beam is stronger than a solid round rod. Moreover, the scientists formed the gel at room temperature and achieved virtually total coupling between the different three-dimensional polymers.
NASA is considering using the new polymer aerogels in inflatable heat shields. Whether they can be used in other applications depends on the cost of the aerogel in commercial quantities. Nevertheless, another application in design is available.
Source: “Flexible, high-strength polymer aerogels deliver ‘super insulation’ properties,” Gizmag, 9/17/12
Source: “New polymer aerogel might become the wonder insulating material,” ZME Science, 9/27/12
Image by NASA.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.