It is a challenge to fabricate graphene bulk materials with properties arising from the nature of individual graphene sheets, and which assemble into monolithic three-dimensional structures. Here we report the scalable self-assembly of randomly oriented graphene sheets into additive-free, essentially homogenous graphene sponge materials that provide a combination of both cork-like and rubber-like properties. These graphene sponges, with densities similar to air, display Poisson's ratios in all directions that are near-zero and largely strain-independent during reversible compression to giant strains. And at the same time, they function as enthalpic rubbers, which can recover up to 98% compression in air and 90% in liquids, and operate between À 196 and 900°C. Furthermore, these sponges provide reversible liquid absorption for hundreds of cycles and then discharge it within seconds, while still providing an effective near-zero Poisson's ratio.

A novel self-healing material, which was fabricated using few-layered graphene (FG) and thermoplastic polyurethane (TPU) via a facile method, not only exhibits a mechanical enhanced property, but also can be repeatedly healed by various methods including infrared (IR) light, electricity and electromagnetic wave with healing efficiencies higher than 98%.

It has been a great challenge to achieve the direct light manipulation of matter on a bulk scale. In this work the direct light propulsion of matter is observed on a macroscopic scale using a bulk graphene-based material. The unique structure and properties of graphene, and the novel morphology of the bulk three-dimensional linked graphene material make it capable not only of absorbing light at various wavelengths but also of emitting energetic electrons efficiently enough to drive the bulk material, following Newtonian mechanics. Thus, the unique photonic and electronic properties of individual graphene sheets are manifested in the response of the bulk state. These results offer an exciting opportunity to bring about bulkscale light manipulation with the potential to realize long-sought applications in areas such as the solar sail and space transportation driven directly by sunlight.U sing beams of light, scientists have been able to trap 1 , move 2 , levitate 3 and even pull 4 small objects (such as atoms and molecules, living cells and viruses, and micro/nanoscopic particles) on the microscopic scale, as well as nano/micrometre-sized graphene sheets 5-7 on a small spatial scale, typically on the order of hundreds of micrometres 8 . There have also been reports of efforts to enlarge the optical manipulation distance by harnessing strong thermal forces 9 , and also the robust manipulation of airborne micro-objects photophoretically with a bottle beam 10 . Furthermore, the rotation and motion of a millimetre-sized graphite disk by photoirradiation has been realized with the graphite levitated magnetically 11 . If these optical operations were to be achieved with large objects on a macroscopic spatial scale, significant applications such as the long-sought direct optical manipulation of macroscale objects (including the proposed solar sail and space transportation via laser or beam-powered propulsion) could be realized. To acquire the required energy and momentum for propulsion, two main mechanisms have been proposed: the use of a laser to superheat a propellant (or air), which then provides propulsion in the same manner as a conventional rocket 4,12,13 , or obtaining propulsion directly from light pressure (radiation pressure) acting on a light sail structure (as with the IKAROS spacecraft) 14,15 .It has been a great challenge to realize the intrinsic properties of single-layer graphene in the bulk state, because stacking of the graphene sheets diminishes most of its properties (electronic, photonic and even mechanical). In this Article, we show that if graphene sheets are assembled in the proper manner into the bulk state, the resulting bulk material not only can retain the intrinsic properties of the individual graphene sheets, but also allows their manifestation on a macroscopic scale. Here, we demonstrate the directly lightinduced macroscopic propulsion and rotation of a bulk graphene sponge material with dimensions on the scale of a centimetre and milligram weight. The mechanism behind this novel phenomenon ...

Smart actuators have many potential applications in various areas, so the development of novel actuation materials, with facile fabricating methods and excellent performances, are still urgent needs. In this work, a novel electromechanical bimorph actuator constituted by a graphene layer and a PVDF layer, is fabricated through a simple yet versatile solution approach. The bimorph actuator can deflect toward the graphene side under electrical stimulus, due to the differences in coefficient of thermal expansion between the two layers and the converse piezoelectric effect and electrostrictive property of the PVDF layer. Under low voltage stimulus, the actuator (length: 20 mm, width: 3 mm) can generate large actuation motion with a maximum deflection of about 14.0 mm within 0.262 s and produce high actuation stress (more than 312.7 MPa/g). The bimorph actuator also can display reversible swing behavior with long cycle life under high frequencies. on this basis, a fish‐like robot that can swim at the speed of 5.02 mm/s is designed and demonstrated. The designed graphene‐PVDF bimorph actuator exhibits the overall novel performance compared with many other electromechanical avtuators, and may contribute to the practical actuation applications of graphene‐based materials at a macro scale.