▎ 摘　　要

Functional materials with excellent electrical and magnetic properties have a potential application in most high-tech fields. Here, superparamagnetic graphene-Fe3O4 (G-F) nanosheet hybrids are prepared by a facile one-step hydrothermal process, which will beneficial to well combine with various polymer matrix to get binary functional composites. Polydimethylsiloxane (PDMS) nanocomposites filled with G-F nanosheets are prepared by a three rolling method. The microstructures of G-F nanosheets as well as the electrical, piezoresistive, and magnetic properties of the G-F/PDMS nanocomposites are investigated. Slightly above the percolation threshold (f(c) = 3.4 wt%), the G-F/PDMS nanocomposites with 3.65 wt% of G-F nanosheets show a high conductivity, which is about 10 orders of magnitudes higher than that of pure PDMS, showing an obvious insulator-semiconductor transition. Moreover, the resistance of the nanocomposites with G-F filler near the percolation threshold exponentially increases with the uniaxial pressure. The normalized resistance (R/R-0) can reach up to 870 at 0.88 MPa with 3.65 wt% G-F nanosheets loading. The G-F/PDMS nanocomposites also show superparamagnetism with saturation magnetization values of 0.21 emu g(-1). These results suggest that the G-F/PDMS nanocomposites in this work provide a new route to fabricate difunctional polymer-based nanocomposites with a potential application as flexible touch sensors.