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Graphene can be conveniently used in the modification of polymer surfaces. Graphene macromolecules are perfectly transparent to the visible light and electrically conductive, consequently these two properties can be simultaneously provided to polymeric substrates by surface coating with thin graphene layers. In addition, such coating process provides the substrates of: waterrepellence, higher surface hardness, low-friction, self-lubrication, gas-barrier properties, and many other functionalities. Polyolefins have a non-polar nature and therefore graphene strongly sticks on their surface. Nano-crystalline graphite can be used as graphene precursor in some chemical processes (e.g., graphite oxide synthesis by the Hummer method), in addition it can be directly applied to the surface of a polyolefin substrate (e.g., polyethylene) to cover it by a thin graphene multilayer. In particular, the nano-crystalline graphite perfectly exfoliate under the application of a combination of shear and friction forces and the produced graphene singlelayers perfectly spread and adhere on the polyethylene substrate surface. Such polymeric materials can be used as ITO (indium-tin oxide) substitute and in the fabrication of different electronic devices. Here the fabrication of transparent resistive deformation sensors based on low-density polyethylene films coated by graphene multilayers is described. Such devices are very sensible and show a high reversible and reproducible behavior. [ABSTRACT FROM AUTHOR]

A simple mechanical technique for polyethylene (LDPE) film coating by a thin graphene layer is here described. This technique is based on the exfoliation of nanocrystalline graphite (few-layer graphene, FLG) by application of shear-stress, and it leads to a thin graphene layer on the plastic substrate with characteristics of good electrical conductivity and perfect transparency in the visible spectral region. These transparent-conductive films are suitable for ITO replacement in optoelectronics and photovoltaics. [ABSTRACT FROM AUTHOR]