Steps towards understanding water-responsiveness

Water responsive materials dramatically alter their size or shape in response to changes in the humidity of their environment, with promising applications in energy storage, soft robotics, and wearable technology. In spite of these potential applications, our understanding of the mechanisms underpinning this key property is poor. Self-assembled tripeptides that exhibit water-responsiveness, due to their simple and highly-tunable structures, could provide us with an excellent test system to probe these interactions on a molecular level. Using fully-atomistic molecular dynamics simulations, we investigate the water responsive tripeptide HYF, noting that hydrogen bonding site occupation is higher at lower humidity levels, causing strengthening of interactions between peptide and water, and leading to contraction of the water channel. We believe that our results, supported by experimental findings, provide some insight into a general mechanism for water responsiveness.