Graphene-based ultralight Cellular elastomer

Graphene, a newly discovered two-dimensional carbon material, possesses a combination of exceptional mechanical, electrical, and thermal properties. These extraordinary properties make graphene an excellent building block for assembling macroscopic materials for widespread applications, ranging from structural materials to flexible electronics. Previous research on graphene bulk material was mainly centred on development of assembly techniques, but little attention has been paid to the engineering of intersheet interactions and assembled architecture. This thesis has developed a graphene cellular monolith with cork-like hierarchical structure through the control of graphene chemistry and assembly behavior. For the first time in graphene bulk material research, superelasticity is observed in the synthesized graphene monolith. This unique hierarchical structure control technique also enables us to produce extremely low density graphene elastomer (≥0.5 mg/cm3, even lower than half of the density of air). By utilizing the electrically conductive function, the dynamic electromechanics of graphene elastomer is investigated. The fast responsive and ultra-sensitive piezoresistive behavior of graphene elastomer is revealed. The graphene elastomer thus provides a new platform material for design of next generation of fast responsive flexible electronics. Additionally, the research demonstrates that using a very small volume fraction of cork-like graphene elastomer (as low as 0.045 vol.%) as reinforcing scaffold is able to significantly enhance the mechanical strength and electrical conductivity of smart hydrogel without compromising its functionality. Such high efficiency reinforcement has proven difficult to be achieved by other nanofiller reinforcement approaches.