Highly conductive natural rubber–graphene hybrid films prepared by solution casting and in situ reduction for solvent-sensing application

High-performance solvent sensors have extensive applications in many fields. In this work, we report a quite efficient method to fabricate electrically conductive natural rubber (NR)-reduced graphene oxide (RGO) hybrid films for solvent-sensing application. The RGO/NR hybrid films with three-dimensional continuous RGO networks were prepared by blending graphene oxide suspension with rubber latex, followed by solution casting and then in situ hydroiodic acid reduction. The electrical conductivity of hybrid film was as high as 49.3 S/m when filled with 5.00 vol% RGO, and the film exhibited an extremely low percolation threshold of 0.31 vol%. The solvent-sensitive properties were evaluated by detecting the variation in electrical resistance due to the swelling of NR matrix. It was noted that the RGO/NR hybrid films exhibited exceptional stimuli responses for organic solvents, however, with different sensing responses for different solvents. Due to the reconstruction of continuous RGO networks after solvent evaporation, the hybrid films performed an excellent repeatability for solvent sensitivity. Therefore, as intelligent materials, the conductive RGO/NR hybrid films have great potential applications in sensing fields.