Conor Pugsley

INTERFACIAL PROPERTIES OF SLIDE-RING POLYACRYLAMIDE HYDROGELS

Conor Pugsley, Andrew Rhode, Angela Pitenis

Hydrogels are a unique class of materials that absorb large amounts of water due to their networks of hydrophilic polymer chains. There have been many recent studies regarding the advancement of hydrogel chemistries for applications ranging from biomedicine to soft robotics, and even atmospheric water harvesting. In many of these applications, interfacial phenomena play a critical role in device function. One hydrogel chemistry with potential to advance these applications involves crosslinks in which rings slide along threaded polymer chains. Compared to traditional hydrogels with immobile, covalent crosslinks, these slide-ring gels have improved toughness and extensibility. Although the bulk mechanical properties of slide-ring gels are well understood, their surface properties remain elusive and uncharacterized. In this project, the elastic modulus and friction coefficient of slide-ring gels and traditional gels were compared to further our understanding of the mechanochemistry of sliding interfaces. The relationship between stiffness and friction in slide-ring gels was measured using a custom-built linear reciprocating tribometer. Trends in the surface properties of slide-ring gels were compared to that of traditional gels using fluid film thickness calculations. We uncover that this novel class of crosslinker creates slide-ring gels that exhibit interfacial behaviors distinct from traditional hydrogels.