Composite Materials Developed with Liquid or Gas Channels

Researchers (L-R) Nancy Sottos, Scott White, and Jeff Moore (L. Brian Stauffer, Univ. of Illinois)

Researchers at University of Illinois in Champaign have developed composite materials with tiny embedded channels, and potential properties such as self-healing or self-cooling. The team published their findings earlier this month in the journal Advanced Materials (paid subscription required).

Composite materials often contain reinforcing fibers such as fiberglass or kevlar that add strength to the basic material. In this case, the composites have tiny channels instead of fibers that can extend through the material as a single route or deploy in a network, such as those found in trees.

The channels can carry liquid or gas that Illinois engineering professor and team leader Scott White says creates “a vascularized structural material that can do almost anything.” The researchers that included (among others) chemistry professor Jeff Moore and engineering faculty member Nancy Sottos created the channels using what are called sacrificial fibers, commercially available fibers that degrade at high temperatures.

Sacrificial fibers are no different from normal fibers during weaving and composite fabrication. When the temperature is raised, however, the treated fibers vaporize, leaving tiny channels in their place, but not affecting the structural composite material itself.

The team demonstrated four types of properties that can be manipulated with different types of fluids circulated through a vascular composite: temperature, chemistry, conductivity and electromagnetism. The researchers regulated temperature by circulating coolant or a hot fluid, and demonstrated a chemical reaction by injecting  chemicals into different vascular branches that merged, mixing the chemicals to produce a luminescent reaction.

They made the structure electrically active by using conductive liquid, and changed its electromagnetic signature with ferrofluids, which have the fluid properties of a liquid and magnetic properties of a solid. Changing electromagnetic signatures can help give an object stealth qualities.

Read more: Researchers Find New Properties in an Old Material

*     *     *