Polymer/Graphene Hybrid Aerogel with High Compressibility, Conductivity, and “Sticky” Superhydrophobicity Han Hu, † Zongbin Zhao,* ,† Wubo Wan, † Yury Gogotsi, †,‡ and Jieshan Qiu* ,† † Carbon Research Laboratory, Liaoning Key Lab for Energy Materials and Chemical Engineering, State Key Lab of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116023, People’s Republic of China ‡ Department of Materials Science and Engineering and A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, Pennsylvania 19104, United States * S Supporting Information ABSTRACT: The idea of extending functions of graphene aerogels and achieving specific applications has aroused wide attention recently. A solution to this challenge is the formation of a hybrid structure where the graphene aerogels are decorated with other functional nanostructures. An infiltration-evaporation- curing strategy has been proposed by the formation of hybrid structure containing poly(dimethylsiloxane) (PDMS) and com- pressible graphene aerogel (CGA), where the cellular walls of the CGA are coated uniformly with an integrated polymer layer. The resulting composite shows enhanced compressive strength and a stable Young’s modulus that are superior to those of pure CGAs. This unique structure combines the advantages of both components, giving rise to an excellent electromechanical performance, where the bulk resistance repeatedly shows a synchronous and linear response to variation of the volume during compression at a wide range of compressed rates. Furthermore, the foamlike structure delivers a water droplet with “sticky” superhydrophobicity and a size as large as 32 μL that remains tightly pinned to the composite, even when it is turned upside-down. This is the first demonstration of superhydrophobicity with strong adhesion on a foamlike structure. These outstanding properties qualify the PDMS/CGA composites developed here as promising candidates for a wide range of applications such as in sensors, actuators, and materials used for biochemical separation and tissue engineering. KEYWORDS: graphene aerogel, compressibility, poly(dimethylsiloxane), electromechanical performance, synergistic effect, superhydrophobicity ■ INTRODUCTION Carbon aerogels represent an attractive form of carbon monoliths with practical importance because of their light weight, high porosity, large surface area, and electrical conductivity. 1-3 These structures can be easily produced by carbonization of polymer aerogels produced using sol-gel chemistry 1,4 and the assembly of novel carbon nanomaterials such as carbon nanotubes, 5-10 carbon nanofibers, 11 gra- phene, 12-20 and their composites. 21-29 Recently, the boom of graphene has aroused wide attention to graphene aerogels, which can harvest the attractive properties of graphene for macroscopic applications. 30 As such, a series of methods have been established to produce graphene aerogels, including hydrothermal reduction, 13,16,18 chemical reduction, 15,19,20 and template-directed chemical vapor deposition. 30,31 Chemically converted graphene nanosheets have been widely utilized as building blocks for the integration of aerogel-like materials due to the diversity in controlling the structures and properties during assembly. 12-20 However, the idea of extending functions of graphene aerogels and achieving specific applications is also highly demanded and requires the formation of hybrid strucutres. 24,25,30,31 Using a functionalization-lyophilization- microwave treatment approach, 15 we reported a compressible graphene aerogel (CGA) with a porosity of up to 99.8% and excellent compressibility. The CGA consists of wrinkled cell walls with an in-plane size of tens to hundreds of microns. These features may allow CGA to be a promising candidate for formation of a hybrid strucutre with outstanding properties such as attractive wettability when combined with materials of low surface energy. Herein, we present an infiltration-evaporation-curing strategy for the fabrication of a poly(dimethylsiloxane) (PDMS)/CGA hybrid structure, where an integrated PDMS layer is formed on the cellular walls of a CGA scaffold, leading to a greatly improved mechanical performance. Furthermore, the unique monolithic structure consisting of graphene@ PDMS demonstrates an excellent electromechanical perform- ance required in electrical devices such as sensors and actuators. Received: November 11, 2013 Accepted: February 13, 2014 Published: February 13, 2014 Research Article www.acsami.org © 2014 American Chemical Society 3242 dx.doi.org/10.1021/am4050647 | ACS Appl. Mater. Interfaces 2014, 6, 3242-3249