Ryan Hayward

Our group has recently demonstrated the use of heterojunctions between oppositely charged ‘ionoelastomers’, i.e., low glass-transition polyelectrolyte networks, for a number of devices, including inherently stretchable and transparent logic elements, low-voltage electroadhesives, and electromechanical transducers. We have recently studied several classes of networks containing different polymer backbone, pendent group, and crosslinker structure and sought to better understand how chemical and structural parameters of the networks influence their device performance. In one example, we have introduced high mobility silicone backbones that lower the glass transition temperature and therefore improve conductivity of the materials. Remarkably, heterojunctions at the interface of polyanionic and polycationic layers of such networks exhibit strongly temperature-dependent rectification, providing insight into the critical role of interfacial polymer dynamics in the operation of these devices. In another example, we have introduced a modular route to prepare polyanionic networks that relies on Sulfur (VI) fluoride exchange (SuFEx) ‘click’ chemistry, enabling a systematic study of how ionic conductivity depends on the length of short perfluorinated pendent groups. A non-monotonic dependence is identified due to the competing effects of ion association and aggregation. Finally, we have studied a variety of different crosslinking species as a route to tune conductivity, stiffness, and toughness of these materials.

Ryan Hayward is the Department Chair and James and Catherine Patten Endowed Professor of Chemical and Biological Engineering at the University of Colorado Boulder. He received degrees in Chemical Engineering from Princeton University (B.S.E, 1999) and the University of California, Santa Barbara (Ph.D., 2004), and was a post-doctoral fellow in Engineering and Applied Sciences at Harvard University from 2004-2005 prior to joining the faculty of Polymer Science and Engineering at UMass Amherst in 2006, where he remained until relocating to the University of Colorado in 2020. His group’s work is broadly focused on responsive materials and self-assembly, including the development of new approaches to optically- and electrically addressable polymers. Ryan received the APS John H. Dillon Medal (2014), the Journal of Polymer Science Innovation Award (2013), the ACS Division of Colloid and Surface Chemistry Unilever Award (2011) and was elected a Fellow of the APS in 2018. He was an Associate Editor for ACS Macro Letters from 2013 – 2022 and in the chair line of the Division of Polymer Physics of the APS from 2021-2025.  

• Time: 11:00 AM
• Location: 206 Furnas Hall