[Oct 3] Kitagawa Group Seminar : Assoc Prof Xi Chen

Kitagawa Group is to hold a seminar. Kyoto University members are welcome to attend.

Assoc Prof Xi Chen
Advanced Science Research Center (ASRC), City University of New York
Department of Chemical Engineering, City College of New York

“Biomimetic water-responsive crystals as high-energy actuators”

ABSTRACT:
In nature, plants have developed water-responsive (WR) materials that mechanically deform in response to changes in relative humidity. These WR materials can harness evaporation and convert it into forces or locomotion that drive plants’ essential tasks, such as pinecones that open and release pine seeds when the environment is dry. Several of these mechanically robust, yet flexible structures can actuate more powerfully than existing actuators and muscles and they hold promise as efficient actuators for energy harvesting, adaptive structures, and soft robotics. Inspired by nature, we have developed a new class of peptide WR crystals that reversibly change their lattice structures in response to humidity changes. The work enables the use of powerful crystallographic methods and simulations to probe molecular level energy conversion in a way that was not possible before. While studying these peptide-based crystals with hierarchical structures and aqueous pores, we found that only the crystals with water bonding strengthening upon dehydration show strong water-responsiveness. Our observations suggest that dehydration-induced hydrogen bonding strengthening efficiently transfers pressure and volume changes induced by water desorption to deform surrounding stiff and ductile structures, providing insight into general mechanisms of high-performance WR actuation. Moreover, the best-performing crystal emerges as an efficient, powerful WR material for applications at scale and low cost.