Fabrication of electrically conductive graphene/polystyrene composites via a combination of latex and layer-by-layer ass
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Weng Weei Tjiu Department of Synthesis and Integration, Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602
Tianxi Liua) State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, People’s Republic of China (Received 4 August 2012; accepted 19 December 2012)
Due to its excellent physical properties, graphene acting as reinforcing fillers has attracted intense interests. To achieve a controlled distribution, the formation of a conductive network composed of graphene sheets within polymer matrix is of critical importance. In this work, polystyrene (PS) microspheres wrapped by graphene oxide (GO) sheets were prepared via layer-by-layer (LBL) assembly of oppositely charged GO sheets onto PS microspheres. The deposited GO was then reduced, and the composite films with a graphene conductive network were prepared by hot pressing. The morphology of graphene conductive network was studied, and the thermal and electrical properties of the composite films were measured. The as-prepared composites showed an improved thermal stability as well as electrical conductivity with a percolation threshold as low as 0.2 vol%. The combination of latex technology and LBL self-assembly method thus demonstrated an efficient and facile approach to fabricate electrically conductive graphene/polymer composites.
I. INTRODUCTION
Graphene, a two-dimensional (2D) nanomaterial composed of sp2-hybridized carbon atoms, has become one of the most exciting research topics since its discovery in 2004.1 Due to its unique structure and excellent physical properties such as mechanical properties, electrical conductivity, mobility of charge carriers, specific surface area, and fascinating transport phenomena, graphene has been intensively used as novel functional materials for a wide range of applications.2,3 Among them, one of the most promising applications of graphene is in the polymer composites, where the mechanical, electrical, or thermal properties of resultant polymer composites can be largely improved by just adding a small amount of graphene.4–7 Graphene is usually prepared via the reduction of graphene oxide (GO), which is considered as the most possible large-scale method for the production of graphene. A main challenge for realizing the preparation of a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2012.437 J. Mater. Res., Vol. 28, No. 4, Feb 28, 2013
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graphene/polymer composites is to homogeneously disperse single graphene sheets within polymer matrix. However, graphene would undergo irreversible aggregations due to strong p–p interactions during reduction. Thus, low dispersibility of graphene in bulk matrices or organic solvents is a major obstacle in the fabrication of graphene/polymer composites by melt compounding or solution mixing since graphene tends to form aggregates in polymer melt or solvents. Many e
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