Aerogels–often referred to as frozen fog–have become an important part of the College's developing efforts in converging technology.
That effort received a major boost with the recent completion of a new lab, made possible by a $250,000 grant from the National Science Foundation. The new lab became fully operational this winter.
Aerogels are approximately ninety to ninety-nine percent air, which allows them to have the lowest density of any inorganic solid. These incredibly light nanostructures also have the lowest known thermal, electrical, and acoustical conductivities, and are excellent insulators. The challenge for researchers is to devise a manufacturing method that will make production of the material more cost effective; current applications are limited mostly to the space program, where aerogels have been used as an insulator on the Mars rover and to collect comet dust.
The interest in aerogels at the College began when Professor of Mechanical Engineering Ann Anderson and a former student, Ben Gauthier '02 (now a graduate student at Stanford), began experimenting. They set three goals”(1) to develop a firm understanding of the factors involved in the formation of aerogels and of current fabrication methods, and ultimately to develop a cost efficient fabrication method for large aerogel monoliths; (2) to optimize the aerogels for various properties, such as thermal conductivity, optical transparency, density, or mechanical strength; and (3) to demonstrate the remarkable properties of aerogels by incorporating them into the design of a product such as a solar cell.
Anderson now is working with a colleague from mechanical engineering, Professor Richard Wilk; Professors Mary Carroll and Michael Hagerman of the Chemistry Department; and mechanical engineering seniors Smitesh Bakrania and Matthew King, and chemistry senior Rebecca Wolfe. Bakrania and Wolfe are making aerogels the subject of their senior theses.
Most recently, the faculty and students discovered that using a thicker rubber gasket yields a quality aerogel in five hours (the old way took about twelve hours). The researchers attribute their success to a combination of hard work and an inventory problem at a local auto parts store.
“We have tried to be systematic but our latest breakthrough was more serendipitous than anything else,” said Anderson.
It turns out the thicker gasket was more compliant, Anderson said. It more evenly distributes the pressure and forms a better seal, making
a higher quality aerogel in
less time.
The team is producing aerogels in a hydraulic, heated press, where they combine a mixture of tetramethylorthosilicate, a catalyst, methanol, and water. The mixture gels and the “wet” gel is then brought to a “supercritical” phase in which there is no surface tension between the liquids and solids. At that point, the wet gel can be dried without degrading the solid matrix inherent in that form of aerogel.
The aerogel team meets weekly to discuss progress. The research is proceeding in two phases, the first focusing on finding improvements in the manufacturing process. The second phase”and the subject of Bakrania's and Wolfe's theses”will be characterizing the properties of the aerogels produced.
The team has applied for a patent on a process they call a “Fast Supercritical Extraction Technique for Simplified Aerogel Fabrication.”