Functional polymethylmethacrylate (PMMA)/graphene nanocomposite microcellular foams were prepared by blending of PMMA with graphene sheets followed by foaming with subcritical CO(2) as an environmentally benign foaming agent. The addition of graphene sheets endows the insulating PMMA foams with high electrical conductivity and improved electromagnetic interference (EMI) shielding efficiency with microwave absorption as the dominant EMI shielding mechanism. Interestingly, because of the presence of the numerous microcellular cells, the graphene-PMMA foam exhibits greatly improved ductility and tensile toughness compared to its bulk counterpart. This work provides a promising methodology to fabricate tough and lightweight graphene-PMMA nanocomposite microcellular foams with superior electrical and EMI shielding properties by simultaneously combining the functionality and reinforcement of the graphene sheets and the toughening effect of the microcellular cells.

As the portable device hardware has been increasing at a noticeable rate, ultrathin thermal conducting materials (TCMs) with the combination of high thermal conductivity and excellent electromagnetic interface (EMI) shielding performance, which are used to effi ciently dissipate heat and minimize EMI problems generated from electronic components (such as high speed processors), are urgently needed. In this work, graphene oxide (GO) fi lms are fabricated by direct evaporation of GO suspension under mild heating, and ultrathin graphite-like graphene fi lms are produced by graphitizing GO fi lms. Further investigation demonstrates that the resulting graphene fi lm with only ≈8.4 µm in thickness not only possesses excellent EMI shielding effectiveness of ≈20 dB and high in-plane thermal conductivity of ≈1100 W m −1 K −1 , but also shows excellent mechanical fl exibility and structure integrity during bending, indicating that the graphitization of GO fi lm could be considered as a new alternative way to produce excellent TCMs with effi cient EMI shielding.

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