Cooley’s chemistry research seeks to understand how to control temperature changes in materials. For example, incorporating negative thermal expansion materials into a composite tooth filling material allows control over how much it expands. “We study materials that exhibit negative thermal expansion — meaning they shrink when you heat them up — so you can use these materials to counteract the detrimental effects of positive thermal expansion,” she explained. They use various elements to understand how changing the elements gives some control over their negative thermal expansion. “The temperature range at which the negative thermal expansion occurs did not change.