Robert Hurt1

1, Brown University, Providence, Rhode Island, United States

Graphene oxide (GO) nanosheets have emerged as important sheet-like, giant molecular precursors for assembling new carbon materials. Colloidal populations of GO nanosheets can be aligned, stacked, folded, crumpled, wrapped, gelled and/or deposited to create a variety of novel material structures. Some of these nanosheet-based materials are not accessible through traditional methods of carbon synthesis that use molecular or bulk solid-state precursors. This approach of “building with graphene” is informed by the science of soft matter, since the key colloidal interactions and conformational changes of GO nanosheets involve weak intermolecular forces and they result in mechanically soft and flexible final products.

This talk will describe our laboratory’s recent work on the systematic exploitation of soft matter behavior to make new GO-based material architectures. We will show how the phenomenon of surface anchoring in lyotropic liquid crystal phases, driven by entropic forces at interfaces, can be used to create vertically aligned GO nanosheets. This lyotropic behavior of GO will be contrasted to the thermotropic behavior shown by molecular systems (discotic liquid crystals), which exhibit multiple anchoring states (homeotropic, planar) depending on both enthalpic and entropic forces that can be tuned by substrate selection. The talk will also describe conformation changes in GO-based films on soft substrates driving by surface instabilities under in-place compression. A variety of wrinkled, crumpled, and hierarchically textured GO films will be demonstrated, and their example applications discussed as stretchable barriers, high-area membranes, and complex templates for ink-based fabrication of textured and tiled ceramic coatings.