Graphene oxide nanoribbons (GOr), obtained by chemically unzipping multi-walled carbon nanotubes, were assembled into macroscopic mats by vacuum filtration. These mats exhibited up to 1.6% reversible contraction when electrically heated at ambient conditions. The experimentally derived work capacity of the mats was about 40 J/kg, which is similar to that of natural muscle. It was limited by the mechanical strength of mats and can be increased upon optimization of their preparation conditions. X-ray diffraction measurements indicated reversible changes in the interplanar spacing of GOr layers during heating. These dimensional changes can be associated with reversible adsorption/desorption of water molecules between GOr layers and used in thermally-driven micro-electromechanical systems (MEMS), micromachines, various opto-mechanic and micro-fluidic devices. Similar to shape memory alloy actuators, GOr mats can be deployed for electrolyte-free artificial muscle applications. The work reported in Chemical Physics Letters, 505 (2011) 31 doi:10.1016/j.cplett.2011.02.005 extends the list of properties available from graphene oxide.
Dr. Mikhail Kozlov is a Research Scientist at the NanoTech Institute, University of Texas at Dallas.