Materials that Change on Demand

The discovery of new materials with novel properties often spurs leaps in science and technology. One of the most promising advances under way now is the creation of "tunable" materials. Caltech aerospace engineer Dennis Kochmann, who works on the modeling and fabrication of novel materials, is using Caltech Innovation Initiative support to design materials whose performance can be altered on demand. The Caltech Innovation Initiative, a philanthropically funded internal grant program, is designed to provide research funds to high-risk but potentially high-reward projects that could produce disruptive technologies with practical applications in the marketplace.

Kochmann started where many research groups are now — focusing on composite materials that change when you add or remove heat. Engineers are designing composites in which a stiff matrix holds phase-transforming inclusions. When an outside force acts to change their phase, the change in the inclusions can change the host material's properties. By using temperature to trigger phase transformation in a tin-barium-titanate composite, Kochmann found that he could increase the material's stiffness and damping (its ability to absorb and attenuate vibration) by orders of magnitude. But he saw that the precise temperature requirements of thermally tunable materials rendered them useless for most practical purposes. So he took a new approach.  

With Caltech Innovation Initiative seed-funding, Kochmann is working to design, fabricate, and test new types of composites with specially designed inclusions that change phase at the push of a button — through application of an electric field rather than changes in temperature. In particular, he wants to create stiff, structural materials that absorb vibration well. The rare combination of high stiffness and high damping would open new possibilities in engineering and science.

Kochmann's new idea could enable many possible outcomes, such as machine beds that isolate lab or factory equipment from vibration, strong and stable aircraft wings, and buildings that better withstand earthquakes.